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I don't do VFX but this was eye opening to me! I always figured lens distortion was just a problem you could overcome with the right track setting. But I just realised if you know the exact distortion, you can use it on your CG elements and more properly integrate it with the footage! Very cool.
When I worked at ILM as a layout artist, we have access to a library of distortion settings for every lens used in an on set shoot. As far as I know, ILM will rent out panavision lenses and do their lens distortion calibration in house. They even have a lens grid set up for recording zoom lens distortions at different focal lengths . Each lens profile is accessible in the in house match moving software. As what the video says, no 2 lens distortion profiles are the same. The Panavision anamorphic lenses have individual distortion profiles. Great video for matchmove artists!
We had a similar setup in The Mill, and yes we often filmed the grids yourself. Thanks so much for your information and contribution, great points in your comment. Thanks
Nice insight. Honestly, that's what I would expect, dealing with that much diverse data/equipment I'm sure it's paid real dividends throughout the years.
@@squigglewacks Which ILM studio did you worked at? I was from the Singapore studio, last film I worked on was Warcraft, the face solving was really tough. Edit - I didn't notice your last bit, nice a lot of my ex colleagues moved to ILM Van.
Thank you so much for sharing your genius, I am Mexican and I admire your work, I have learned and developed my work thanks to you, and I love nuke thanks to your way of teaching and transmitting, now I learn Houdini and follow your steps! Thank you so much for your life!
Hugo's Desk You are welcome whenever you want, it would be an honor to have someone with such talent and knowledge in our country, for my part I will continue to follow you and learn from you. I also hope to go to your beautiful and powerfully cultural country! God keep blessing you
One of the not so cool things as an On Set VFX Supervisor: Having to make the camera assistant go through all the lenses and cameras used that day while everybody else has already wrapped up. Yes, it's necessary, but the camera assistent will not like it. And it's always good to be best friends with the camera assistent on set, as that is the person that will keep you informed about all things camera.
Yes for sure, this is why I always insist to have many meetings and face to face gatherings with the crew before the shoot. Gives me opurtunity to talk to them, explain what I need and to buy them a drink! lol
@@HugosDesk I would love to hear more from you about set supervision in a video or talk. All I know is self taught and I'm sure I could still learn a lot. Not many tutorials out there about that topic 😅
If its a feature film there are usually camera tests done before the main shoot to test all the cameras and lenses. This is the perfect time to shoot lens grids if you're in contact with camera team and/or a producer before that. Hopefully the production understands the value of doing it.
Always try to shoot the grids at the Cam Hire on the Gear Check day *before the shoot. Trying to shoot them *during the shoot is difficult, and shooting them after wrap is horrible ;) (as has been stated before). Shooting them before : Pro - All lenses done. Relatively easy as cameras / lenses / cam dept all there. Con - All lenses have to be shot (you don't know which ones will be used), so takes longer. Shooting them after : Pro - You only have to shoot lenses that have been used (so quicker). Also more accurate focal lengths on zooms Con - Have to organise Cam Hire / camera / lenses / crew after shoot. Nice video btw.
That is a great suggestion. I have always done it at the camera hire but after the shoot. Before sounds much better, going to do that next time. Thanks
I like how you comped Bjorn in at the end! Also, thank you so much for this overview and links. Got a tracking shot in a couple of months and this is a big save.
@@ginglyst yeah you're right, its probably easier to only distort the cg elements and then compose them into the original. This is really just about the tracking information. Otherwise you'll potentially lose image quality.
The correct workflow is: Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements The undistortion of the footage is only for tracking not to use. There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should: Undistort Footage -> scale/reposition shot in the CG -> redistort everything
@@k1ngjulien_ Yes that is true, undistorting will filter your image with a Cubic filter by default so it will be softer. So always avoid touching the plate. There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should: Undistort Footage -> scale/reposition shot in the CG -> redistort everything
undistort original footage -> track shot ->export the camera to 3d softwares and use undistorted footage as reference behind-> render out cg elements-> add CG renders with distortion values to original footage
Nice video. Worth adding that you'll need to shoot grids for *every camera used on the shoot. Many jobs shoot with more than 1 camera, and they all need grids. To be safe even those that 'are not VFX shots' :) Example : A-Cam: Alexa LF, B-Cam: Alexa mini, C-Cam: Drone. Etc. Also, just a note about the lens grid practical size - 8x4 ft. This is pretty standard. As Hugo stated, you need the big size to get full-frame grids on wider lenses, esp. Anamorphic. Obviously you achieve 'full frame' by moving the camera closer to the grid, until it fills frame. With a short Anamorphic lens (eg. 18mm), the camera will be pretty close to the grid, as the lens is so wide. If your grid is small, you'll probably be so close that you won't be able to focus on it. So a big grid is better than a small one because you'll be further away. Hope that makes sense ;)
Hugo's Desk , Very helpful information! In another comment you clear up the correct workflow (Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements). I was wondering if you had a similar clear workflow for the order of color grading in VFX that's most flexible for color changes made after the VFX plates have been created. Curious to hear your thoughts.
Great video! shooting lens grids is not done often enough. If you are on set or a shoot as a VFX sup you should try your best to get grids shot (in commercial work it doesn't always get done). Makes everything go much smoother in post. Remember the more time spent on this stuff equals more time for the artists to perfect the shot and comp and less time fixing a bad track.
Very informative, but keep in mind that depending on capture resolution and density of the sensor, f/22 could easily be diffraction limited and f/11 or f/8 sharper, especially with lenses that have a flat focus field.
Nice video, I am wondering about your preferred f22 setting for film the grid. I personal do a range of f-stops if I have the time, because most lenses have a fair bit of breathing when changing aperture in addition to focus-breathing. When I am pressed for time (always basically), I prefer f8 as a nice lens sweet spot and closer to the exposures used in the shoot.
You are absolutely correct. If I have time I do a range of F-stops (especially if the lenses are anamorphic) but most of the times I am onset I end up making only F8 because... you know, 1st ADs! haha
Really useful video, thanks. How do you ensure that you are directly facing the lens grid, ie the lens vs the two corners of the distortion chart are at exactly the same distance? You kinda skimmed over how to achieve that? I understand about levelling the chart and camera, and setting the height of the camera and chart to be the same, but it's 3D space. I know in stills photography they use a mirror in the centre of the grid. Cheers
Thanks for watching. I use laser measurement tools onset if I have time. The reason I did not mention this is that when onset you usually have very little time to do this so most of the time it's done by eye and as best as possible. If you have time I personally use this to line up and measure: amzn.eu/d/dA4c29k and this: amzn.eu/d/aS7RkjA
As a full cg comp artist trying to move to live action by doing small project at home, this couldn't have been more timely! I knew enough of the nuke part to get by, but my grid filming method was meh.
@@HugosDesk Are you familiar with Captain Disillusion? If not, he debunks video pranks because he understands cgi elements, lens distortion, and tracking elements. In short, he is just like you with the dissemination of video knowledge.
@@HugosDesk I use my phone to shoot videos so a normal sized chessboard is enough for me to correct lens distortion. coz i am not a professional artist i just do vfx for fun and absolutely love watching your videos. They have so much great content to learn.
Neat. I'm not in the industry, but I'm here because I was looking up how to get rid of some distortion with my action-cam. Specifically it has some distortion correction but is still not 100%, so I wanted to see if I could further do something. I'm considering using Blender for actual editing, and through a tutorial for Blender this was in the recommended on the side. So now I'm thinking, maybe I want to do this grid thing, since it will only be a one time set up. Will consider it, although I probably don't strictly need to do it, for essentially off the cuff vlogs.
Thanks for watching it. Yes, that is correct, if you read the documentation I shared on the links you can see the process. You just need to film the lens at different focal lengths.
Little question - how different would the results be doing it this way compared to the K1, K2 values you get when getting a solve from your matchmoving software? For example, if you do a 3D track in Blender, you can estimate K1, K2 and get the lens distortion values using the tracking data. Would that be far less accurate compared to doing it with a dedicated lens grid?
@@HugosDesk Might want to consider putting hardware descriptions of gear used in your vids maybe with amazon aff links, or something like the kit gear website. And linking to your kickstarter
@@TheNewton My kickstarter finished 1 month ago so not gong to post links anymore. Regarding equipment, youtube does not allow annotations anymore or links on top. Sorry.
I'm just very noob on this subject, I think the crome ball specular part is for the HDRI reflections but, what is the diffuse part for? And where I can learn how to use the ball and the color pallete thingy?
i'm sorta stumbling through thiss process as a beginner. i make fpv drone videos, those are the fast drones that can do aerobatic stuff. anyway our cameraa choices are limited, and since we crash a lot for most of us gopro hero 7's and session 5's are not a sensible option. a new camera called the runcam 5 and the split 2 are my cameras, is there any chance you could do a more detailed tutorial on how to do this lens map and i noticed your corrected field of view was quite heavily cropped? i assume its possible to zoom and get that field of view back? wider fov is better for fast moving flight.
Yes a simple reformat without scaling will ‘open’ the canvas/boundary box in Nuke. My video is a simple intro and I don’t have plans to make a sequel yet because I am covering this on my Nuke course. But it is simple Industry standard to increase the resolution of the plate without scaling pixels, so it’s affectively like increasing the canvas in Photoshop without scaling, but in Nuke. You know what I mean?
@@HugosDesk thanks yeah i know about scaling and canvas size in photoshop, in premiere its extremely vague on whats going on with scale, as you did' if you apply simple lens correction it zooms in quite a lot.it wasn't until i discovered '' camera view'' option to push the image into the 'distance' i was able to lens correct without the heavy cropping, nuke, and the nodes process looks super vague, i've had a play with them in davinci resolve but as a workflow? it was hard to get a solid technique,
I wonder if a lot of the setup and manual work could be solved by using OpenCV's undistort and multiple captures. At least in the computer science world, that's what we typically do, and if it's good enough for 3D there (solvePnP), it should be enough for VFX. Plus, then you don't need expensive software!
I am sure it would do a good job. But using a lens grid is still the most effective and easiest method at the moment. What I show in the video is industry standard. And regarding‘expensive’ software, well all VFX softwares are expensive and all VFX studios would already have Nuke or a 3D tracking software to do this.
Informative video. One suggestion/request, please try to cover how to render overscaned sequence after removing distortion from nuke for CG application. Thanks Hugo :-)
Well that is beyond the scope of this video. This video is about filming the Grid. What you are suggesting is a purely CG and Nuke video so it would have to be separate. I would need a lot more then 8 mins for that. I am trying to make a short video to get people started on distortion. As I mention on the video there is a lot more to this. I will make a sequel eventually. Thanks for watching
Hello, thank you very much for this video. The "On-Set Visual Effects Documentation by Niles Heckman" link was broken, would you have access to an alternate?
It’s seems like the site is down. It says ‘coming soon’ in the root site. I have downloaded a PDF a few months ago. Maybe this can help? www.dropbox.com/s/xy0qaowz1dev882/GKR%20Set%20Documentation.pdf?dl=0
That is a HDR sphere or a 'Crome Ball'. We use it for light reference. So when we do the real HDRs on set with a full frame and a 8mm we can check the orientation of the sphere and double check light direction. Normally in CG you would place a CG sphere next to this sphere. If they match then your lighting is good. It's just for reference.
I think I t will be difficult to film a screen big enough for a wide lens and also because of exposure and shutter speed you may have problems. I would recommend print a large grid.
Hey Hugo! Great video as always! I am doing this TOMORROW so this came in like a godsend. One question: Is it necessary to shoot the grid when they downrez the camera? We are using the Red Mostro and while mostly they shoot 8K sometimes they downrez to 6K and 4K in camera. Do I need a grid downrezed as well? When you're in Spain hit me up, I'll take you for some amazing tapas and beers, man!
No problem. Glad you liked. If it is a sensor crop you can probably crop your main 8K Grid but personally, for safety, I would film the Grid at all sensor crops and resolutions just to make sure it is all correct.
Probably a bit late, but I hope someone has an answer to my question. What happens if you film with a zoom lens and the DOP zooms in the shot itself? The mm's differs, right? How do you make a distortion grid then?
It's not mandatory but I find the cross easier to line up the camera with the grid at perfect 90 degrees on both vertical and horizontal axis. And the inner smaller checkboard is very useful if you have a telelens above 100mm. Hope this helped
@@HugosDesk This helped me tremendously. Thank you. I also had another question if that is possible. Do you have any tips for shooting a lens distortion grid for a zoom lens?
Wondering how important the size of the grid is? Eric Albas pdf's are 8ft by 4ft, yours looks much smaller, hard to tell but possibly 5ft? Have you run into any limitations using the smaller (more practical) size?
We did small because we could get a bigger one at the time for the video. But the size is linked to how wide you are filming. It needs to be big enough to cover the entire lens and still be in focus so the wider you are the bigger it will be. Eric’s size is the perfect size to cover any lens you have from a 12mm to anything in between. If you for example only have a 35 or a 50 as the widest then the grid can be relatively small.
@@HugosDesk If we are shooting with a zoom lens, is the lens distortion the same if we are zoomed in or zoomed out on the lens? If we shoot wide and we zoom in to cover the printed grid, would that work? Thanks for your time .
@@ChrisGunningham-t1x With a zoom lens you would have to film several focals of the lens to cover distortion in the entire lens. I would recommend going step by step and filming as many locals as you filmed. Most lenses these days can do metadata so you could find out what focal was used. Filming all locals is crucial for the 'lens focus breathing'
AWESOME explanation your stuff is always so deep it can be hard for a hobbyist to follow. Couple of questions: 1. How punishing is it to do the distortion grid AFTER alot of compositing has been done? Convincing non-VFX people that prep like this has to be done seems like a hard social aspect. For a big production i'd assume there'd be tech days scheduled but for smaller amateur stuff probably not. 2. How does getting time with camera+lens typically work out? (I mean it doesn't seem non-trivial convincing someone to either give you their gear, or make them show up early,or stay late )
Thanks so muhc for watching and for the kind words regarding my video. Regarding your first question, not sure what you mean about 'social aspect'. In a VFX house lens distortion is part of the pipeline, it is essential and necessary. It is not an option. We work in accuracy and photorealism. Regarding number 2, this is normally part of the shoot's schedule. I always talk with production and the 1st AD and we decide together when is the best time to make this happen. I have also done it back at the rental house a few times. That also works.
@@HugosDesk For the social aspect I mean like says it's an indie production and no one is used to VFX so different departments have to be convinced/educated to get time with different equipment.
I understand that solving the lens distortion needs straight lines, but do they actually need to be level in frame? Is there any downside if the grid is rotated?
Well, the straighter it is the easier it is for the software to calculate an accurate lens map. It will probably work just fine without levelling but I tend to make sure it is as perfect as possible.
@@HugosDesk makes sense that nuke is tuned to detect horizontal/vertical lines. So shooting it level should save a lot of manual work drawing lines. I appreciate the quick response!
The correct workflow is: Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements The undistortion of the footage is only for tracking not to use. There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should: Undistort Footage -> scale/reposition shot in the CG -> redistort everything
Hi, first off, VFX is a team effort, so yes I do "all of this" to help my 3D tracking team. Second, any CG, Matte painting elements that will be composited to a plate of live-action needs to have the same distortion. So you need to 'redistort' all the elements before compositing any of them on top of your footage.
I printed a smaller one this time because I only had to film one lens for this show I was filming at Sony. It needs to be big enough for the widest lens you have with the sharpest possible image. So if you point your camera and the widest lens to a wall, find the closest sharp position from the wall, just measure the limits of the screen and that is the size you need.
@@HugosDesk One more question. How is in the case that I have a 16mm but as I use the bmpc 6k is super 35mm. So the 16mm would end up being a 24. The true number would be de 16mm or 24 because of the sensor crop? thanks
If WE WANT TO PRACTICE IT , SO HOW DO WE GET THE LENS DISTORTION CARDS and please tell me at this point i am right or not , lens distortion is used so that we get proper tracking data , and the 3d objects we will place while compositing doesnt get strecht or distort ?? am i right or not ! please help me by replying! and i also want the nuke manual do read from where do i get that ?? btw thanks
Hi, yes you are correct. Regarding the Nuke Manual, it’s included inside Nuke. Just go to the help tab and select help. It’s all there. Thanks for watching
You can’t really buy them. You usually need to print them on demand for the project since they can’t be curved by humidity or wrinkled by time. I have some links on the video description for the instructions
Did not watched the video yet but is lens distortion not dependent on the distance betwen the lens and the talent/object you film ? And then how many lens distortions profiles you make ?
Well, most VFX productions are filmed with Primes but if you read the documentation on the links you can see that filming a zoom lens is the same as filming several lenses. You need to film the grid at several focal. Example if the zoom is 24-105 then you film at 24, 35, 50, 85 and 105. You just have to film several grids to 'map ' the different distortions of the zoom.
To correctly 'map' the lens distortion you need to be pretty sharp when filming the grid. So a high Fstop and pulling focus to the grid. Taking a few grids on lower f-stops matching the plates could be a good reference for aberration but it won't helo the mapping of the lens.
@@insanejughead - Forget Bond. He always gets lost, even with an address and a flashing goalpost. He is British. Just look up Brexit. The Brits are all like this. That's why they lost their Empire. Now they are even losing their own country. No, I need someone like Kevin Mitnick, not like Bond.
.Sir please make a tutorial undistort a short using 3DEqualizer, and add 3d elements and composite in nuke, if it is exist reply the link. I will be most thank full to you.
you just have to be better at explaining the workflow when the undistorted image is now beyond the bounding box, because when the distortion is reapplied to the final output everything you composite in-between will be missing at the edges. I know, but it can be a real headache if you dont.
You are a funny guy! Haha. You know I actually recorded that part and I removed it because I thought it may confuse people. I think that is beyond the scoop of this video. This video is about filming the grid the grid itself. But it is simple, just increase your canvas using a reformat. If you add pixels around your image without scaling then you grow your edges. If you want come by my Twitch Thursdays streams and ask that on the chat and I can shot it live. Thanks for watching
Well, most VFX productions are filmed with Primes but if you read the documentation on the links you can see that filming a zoom lens is the same as filming several lenses. You need to film the grid at several focals . Example if the zoom is 24-105 then you film at 24, 35, 50, 85 and 105. You just have to film several grids to 'map ' the different distortions of the zoom.
To celebrate springtime my Nuke compositing courses are 60% Off until the 1st of April. This is the biggest discount ever! Don’t miss this offer. Use the promo code SPRINGSALE during checkout: hugosdesk.myshopify.com/discount/SPRINGSALE
Two courses are available to buy:
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👉Access to 150 classes (already available, extra classes dropping soon)
👉More classes soon!
👉50+ hours of training
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All courses include:
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I don't do VFX but this was eye opening to me! I always figured lens distortion was just a problem you could overcome with the right track setting. But I just realised if you know the exact distortion, you can use it on your CG elements and more properly integrate it with the footage! Very cool.
Thanks so much for watching and I am so glad you enjoyed it
I think I know what I will be seeing in this week's email
When I worked at ILM as a layout artist, we have access to a library of distortion settings for every lens used in an on set shoot. As far as I know, ILM will rent out panavision lenses and do their lens distortion calibration in house. They even have a lens grid set up for recording zoom lens distortions at different focal lengths . Each lens profile is accessible in the in house match moving software. As what the video says, no 2 lens distortion profiles are the same. The Panavision anamorphic lenses have individual distortion profiles. Great video for matchmove artists!
We had a similar setup in The Mill, and yes we often filmed the grids yourself. Thanks so much for your information and contribution, great points in your comment. Thanks
Nice insight. Honestly, that's what I would expect, dealing with that much diverse data/equipment I'm sure it's paid real dividends throughout the years.
@@squigglewacks Which ILM studio did you worked at? I was from the Singapore studio, last film I worked on was Warcraft, the face solving was really tough. Edit - I didn't notice your last bit, nice a lot of my ex colleagues moved to ILM Van.
Oh my.
As a tracking and matchmoving artist, this is really useful, especially for new cameras- thanks so much! STmaps can be annoying at times
No problem, thanks so much for watching and don’t forget to share it around. Glad you enjoyed it.
Sure will, especially to my studio and matchmoving friends
Thanks so much for that.
Bjorn seems incredibly nice.
Thank you so much for sharing your genius, I am Mexican and I admire your work, I have learned and developed my work thanks to you, and I love nuke thanks to your way of teaching and transmitting, now I learn Houdini and follow your steps! Thank you so much for your life!
Thanks so much for the kind words. Never been in Mexico yet maybe one day I can visit your beautiful country. Thanks mate
Hugo's Desk You are welcome whenever you want, it would be an honor to have someone with such talent and knowledge in our country, for my part I will continue to follow you and learn from you. I also hope to go to your beautiful and powerfully cultural country! God keep blessing you
Best VFX learning channel on TH-cam......
Thanks so much but there are a few good other channels. But thanks so much for the compliment. I’ll take it! Haha 😆
One of the not so cool things as an On Set VFX Supervisor: Having to make the camera assistant go through all the lenses and cameras used that day while everybody else has already wrapped up. Yes, it's necessary, but the camera assistent will not like it. And it's always good to be best friends with the camera assistent on set, as that is the person that will keep you informed about all things camera.
Yes for sure, this is why I always insist to have many meetings and face to face gatherings with the crew before the shoot. Gives me opurtunity to talk to them, explain what I need and to buy them a drink! lol
@@HugosDesk I would love to hear more from you about set supervision in a video or talk. All I know is self taught and I'm sure I could still learn a lot. Not many tutorials out there about that topic 😅
If its a feature film there are usually camera tests done before the main shoot to test all the cameras and lenses. This is the perfect time to shoot lens grids if you're in contact with camera team and/or a producer before that. Hopefully the production understands the value of doing it.
Always try to shoot the grids at the Cam Hire on the Gear Check day *before the shoot. Trying to shoot them *during the shoot is difficult, and shooting them after wrap is horrible ;) (as has been stated before).
Shooting them before : Pro - All lenses done. Relatively easy as cameras / lenses / cam dept all there. Con - All lenses have to be shot (you don't know which ones will be used), so takes longer.
Shooting them after : Pro - You only have to shoot lenses that have been used (so quicker). Also more accurate focal lengths on zooms Con - Have to organise Cam Hire / camera / lenses / crew after shoot.
Nice video btw.
That is a great suggestion. I have always done it at the camera hire but after the shoot. Before sounds much better, going to do that next time. Thanks
I like how you comped Bjorn in at the end!
Also, thank you so much for this overview and links. Got a tracking shot in a couple of months and this is a big save.
Björn was there with me onset! For real!
This video convinced me to finally make my own lens grid. thank you!!
So the workflow is:
Undistort Footage -> track shot -> add cg elements -> distort footage back again
Correct?
hmm I would guess
Undistort Footage -> track shot -> add cg elements -> distort cg elements -> merge Undistort Footage and distorted cg elements
@@ginglyst yeah you're right, its probably easier to only distort the cg elements and then compose them into the original.
This is really just about the tracking information.
Otherwise you'll potentially lose image quality.
The correct workflow is:
Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements
The undistortion of the footage is only for tracking not to use.
There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should:
Undistort Footage -> scale/reposition shot in the CG -> redistort everything
@@k1ngjulien_ Yes that is true, undistorting will filter your image with a Cubic filter by default so it will be softer. So always avoid touching the plate.
There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should:
Undistort Footage -> scale/reposition shot in the CG -> redistort everything
undistort original footage -> track shot ->export the camera to 3d softwares and use undistorted footage as reference behind-> render out cg elements-> add CG renders with distortion values to original footage
full professional tutor
Thanks so much for watching
Nice video.
Worth adding that you'll need to shoot grids for *every camera used on the shoot.
Many jobs shoot with more than 1 camera, and they all need grids. To be safe even those that 'are not VFX shots' :)
Example : A-Cam: Alexa LF, B-Cam: Alexa mini, C-Cam: Drone. Etc.
Also, just a note about the lens grid practical size -
8x4 ft. This is pretty standard.
As Hugo stated, you need the big size to get full-frame grids on wider lenses, esp. Anamorphic.
Obviously you achieve 'full frame' by moving the camera closer to the grid, until it fills frame.
With a short Anamorphic lens (eg. 18mm), the camera will be pretty close to the grid, as the lens is so wide.
If your grid is small, you'll probably be so close that you won't be able to focus on it.
So a big grid is better than a small one because you'll be further away.
Hope that makes sense ;)
We JUST started doing this at work. 🤦♂ About dang time! Great vid! Super helpful!
Thanks Again Hugo, your such a great help, i hope you make more tutorials on HDRi balls and color checkers for white balance !
I have one on HDRI. I mostly do videos from Patreon requests. Maybe become a Patreon and vote?
Thanks guys. Very informative
this information is very useful - thanks Hugo !
Thank you
Superb job! good luck Hugo!
Thanks so muhc for the support. Men's a lot to me
Hugo's Desk , Very helpful information! In another comment you clear up the correct workflow (Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements). I was wondering if you had a similar clear workflow for the order of color grading in VFX that's most flexible for color changes made after the VFX plates have been created. Curious to hear your thoughts.
Great video! shooting lens grids is not done often enough. If you are on set or a shoot as a VFX sup you should try your best to get grids shot (in commercial work it doesn't always get done). Makes everything go much smoother in post. Remember the more time spent on this stuff equals more time for the artists to perfect the shot and comp and less time fixing a bad track.
Exactly! You said it!
excellent lesson hugo
Thanks so much. Don’t forget to share and always film a lens distortion grid!
So valuable information just inside an 8 minutos video!!!
Thanks so muhc. You should join me on Twitch, a lot more there. Image 2 hours of info! haha
@@HugosDesk I'll go for that!
Very informative, but keep in mind that depending on capture resolution and density of the sensor, f/22 could easily be diffraction limited and f/11 or f/8 sharper, especially with lenses that have a flat focus field.
Yes you are correct. Thanks for the comment.
Nice video, I am wondering about your preferred f22 setting for film the grid. I personal do a range of f-stops if I have the time, because most lenses have a fair bit of breathing when changing aperture in addition to focus-breathing. When I am pressed for time (always basically), I prefer f8 as a nice lens sweet spot and closer to the exposures used in the shoot.
You are absolutely correct. If I have time I do a range of F-stops (especially if the lenses are anamorphic) but most of the times I am onset I end up making only F8 because... you know, 1st ADs! haha
@@HugosDesk Hehe, yes our trusty friend onset! :)
WOW I wouldn't even imagine that, awesome!
Thank you so much Hugo
No problem. Glad you liked it. Now share it with your friends and family! Haha
@@HugosDesk I will :)
thanks for making this content! very usefulll
Glad you enjoy it!
WOA! I semi know this guy and now YT is recommending him to me. Best. Lecture. Ever. *Sponcered by American Ninja (1985)
Haha thanks so much for watching that one. It was a special one. Thanks
Really useful video, thanks. How do you ensure that you are directly facing the lens grid, ie the lens vs the two corners of the distortion chart are at exactly the same distance? You kinda skimmed over how to achieve that? I understand about levelling the chart and camera, and setting the height of the camera and chart to be the same, but it's 3D space. I know in stills photography they use a mirror in the centre of the grid. Cheers
Thanks for watching. I use laser measurement tools onset if I have time. The reason I did not mention this is that when onset you usually have very little time to do this so most of the time it's done by eye and as best as possible. If you have time I personally use this to line up and measure: amzn.eu/d/dA4c29k and this: amzn.eu/d/aS7RkjA
Another great video, thanks Hugo!
As a full cg comp artist trying to move to live action by doing small project at home, this couldn't have been more timely! I knew enough of the nuke part to get by, but my grid filming method was meh.
I am glad I could help. Have a read on the links I left in the description. A lot more info. My video is just a ‘starter’ video
Thank you so much for making this video. I learned a lot looking forward to hearing your next video
Thanks s much for watching
this explain my problems with tracking, Thanks a lot hugo!!
Awesome tutorial! Thanks Hugo
Thanks for watching
I never knew this was a thing. Do they keep the "fixed warp" for final product? Or do you only use the warp to get work done, like to track
Yes it is common. We use the ‘fixed warp’ only to 3D track. But we apply ‘warping’ to the CG and matte painting elements to match the lens distortion.
@@HugosDesk that's really interesting. Thanks for the in depth videos, and interaction in the comments. 👍🏻
@@DarkSpaceStudios No problem. Thanks so much for watching
Really useful video, cheers Hugo
Thanks for giving information
Hugo you are best....
You are too kind! Be safe
pretty useful stuff to learn. Thanks !
I problem, glad you liked it.
On point as always! Thanks
You are too kind. Don’t forget to share
Quick, someone call on Captain Disillusion!
P.s. This is great knowledge. Many thanks, sir!
Thanks???
@@HugosDesk Are you familiar with Captain Disillusion?
If not, he debunks video pranks because he understands cgi elements, lens distortion, and tracking elements.
In short, he is just like you with the dissemination of video knowledge.
Great video!
Thanks mate
wow! This is great!
Thanks
That was neat!
Thanks
i was pretty low on budget so i used my chessboard as the lens grid!
Haha, that is funny. How did you manage to film a wide lens? How big is this chessboard?
@@HugosDesk I use my phone to shoot videos so a normal sized chessboard is enough for me to correct lens distortion.
coz i am not a professional artist i just do vfx for fun and absolutely love watching your videos. They have so much great content to learn.
That is great stuff. Thanks so much for watching. You have anything online to check? Would love to see it
@@HugosDesk ya i have a few test videos on my channel
Neat. I'm not in the industry, but I'm here because I was looking up how to get rid of some distortion with my action-cam. Specifically it has some distortion correction but is still not 100%, so I wanted to see if I could further do something. I'm considering using Blender for actual editing, and through a tutorial for Blender this was in the recommended on the side. So now I'm thinking, maybe I want to do this grid thing, since it will only be a one time set up. Will consider it, although I probably don't strictly need to do it, for essentially off the cuff vlogs.
This got recommended. I did learn something about vfx
???
@@HugosDesk i just got it recommended. Although i did learn something about vfx
Who is the hand actor @7:29? I want to hire him :) nice video Hugo
The most beautiful hand! Thanks mate
thanks for information
It is me or Bjorn looks exacly like Seth Rogen
its you, and you need glasses
thanks hugo
I wish I had known about this when I filmed my last short film lol
Well now you know! I hope you do a new film soon and share it with us. Thanks for watching
Great Hugo! So I guess when we have a zoom lens we have different distortions for different focal length??
Thanks for watching it. Yes, that is correct, if you read the documentation I shared on the links you can see the process. You just need to film the lens at different focal lengths.
Little question - how different would the results be doing it this way compared to the K1, K2 values you get when getting a solve from your matchmoving software? For example, if you do a 3D track in Blender, you can estimate K1, K2 and get the lens distortion values using the tracking data. Would that be far less accurate compared to doing it with a dedicated lens grid?
yes
Thank you!
Thanks a lot!
Where i get Crome Ball that u use in video @ 4:18
www.vfx-store.com/ball-kits
@@HugosDesk Might want to consider putting hardware descriptions of gear used in your vids maybe with amazon aff links, or something like the kit gear website. And linking to your kickstarter
@@TheNewton My kickstarter finished 1 month ago so not gong to post links anymore. Regarding equipment, youtube does not allow annotations anymore or links on top. Sorry.
I'm just very noob on this subject, I think the crome ball specular part is for the HDRI reflections but, what is the diffuse part for? And where I can learn how to use the ball and the color pallete thingy?
i'm sorta stumbling through thiss process as a beginner. i make fpv drone videos, those are the fast drones that can do aerobatic stuff. anyway our cameraa choices are limited, and since we crash a lot for most of us gopro hero 7's and session 5's are not a sensible option. a new camera called the runcam 5 and the split 2 are my cameras, is there any chance you could do a more detailed tutorial on how to do this lens map and i noticed your corrected field of view was quite heavily cropped? i assume its possible to zoom and get that field of view back? wider fov is better for fast moving flight.
Yes a simple reformat without scaling will ‘open’ the canvas/boundary box in Nuke. My video is a simple intro and I don’t have plans to make a sequel yet because I am covering this on my Nuke course. But it is simple Industry standard to increase the resolution of the plate without scaling pixels, so it’s affectively like increasing the canvas in Photoshop without scaling, but in Nuke. You know what I mean?
@@HugosDesk thanks yeah i know about scaling and canvas size in photoshop, in premiere its extremely vague on whats going on with scale, as you did' if you apply simple lens correction it zooms in quite a lot.it wasn't until i discovered '' camera view'' option to push the image into the 'distance' i was able to lens correct without the heavy cropping, nuke, and the nodes process looks super vague, i've had a play with them in davinci resolve but as a workflow? it was hard to get a solid technique,
@@TheMadmacs Well you should be doing this in a compositing software like Nuke, Fusion or if you don't access to the first 2, then After Effects.
I wonder if a lot of the setup and manual work could be solved by using OpenCV's undistort and multiple captures. At least in the computer science world, that's what we typically do, and if it's good enough for 3D there (solvePnP), it should be enough for VFX. Plus, then you don't need expensive software!
I am sure it would do a good job. But using a lens grid is still the most effective and easiest method at the moment. What I show in the video is industry standard. And regarding‘expensive’ software, well all VFX softwares are expensive and all VFX studios would already have Nuke or a 3D tracking software to do this.
But I will look into this. So thanks for the suggestion
Informative video. One suggestion/request, please try to cover how to render overscaned sequence after removing distortion from nuke for CG application. Thanks Hugo :-)
Well that is beyond the scope of this video. This video is about filming the Grid. What you are suggesting is a purely CG and Nuke video so it would have to be separate. I would need a lot more then 8 mins for that. I am trying to make a short video to get people started on distortion. As I mention on the video there is a lot more to this. I will make a sequel eventually. Thanks for watching
Btw this is all covered on my online Nuke course on Kickstarter. Thanks
Hello, thank you very much for this video. The "On-Set Visual Effects Documentation by Niles Heckman" link was broken, would you have access to an alternate?
It’s seems like the site is down. It says ‘coming soon’ in the root site. I have downloaded a PDF a few months ago. Maybe this can help? www.dropbox.com/s/xy0qaowz1dev882/GKR%20Set%20Documentation.pdf?dl=0
Thank you so much !! 😇
What's the Sphere called and what is it used for in 4:19?
That is a HDR sphere or a 'Crome Ball'. We use it for light reference. So when we do the real HDRs on set with a full frame and a 8mm we can check the orientation of the sphere and double check light direction. Normally in CG you would place a CG sphere next to this sphere. If they match then your lighting is good. It's just for reference.
Thanks Hugo. Great stuff :) Can I display the grid on a monitor that has been leveled and then record it there or will that somehow give a bad result?
I think I t will be difficult to film a screen big enough for a wide lens and also because of exposure and shutter speed you may have problems. I would recommend print a large grid.
Hey Hugo! Great video as always! I am doing this TOMORROW so this came in like a godsend. One question: Is it necessary to shoot the grid when they downrez the camera? We are using the Red Mostro and while mostly they shoot 8K sometimes they downrez to 6K and 4K in camera. Do I need a grid downrezed as well? When you're in Spain hit me up, I'll take you for some amazing tapas and beers, man!
No problem. Glad you liked. If it is a sensor crop you can probably crop your main 8K Grid but personally, for safety, I would film the Grid at all sensor crops and resolutions just to make sure it is all correct.
Probably a bit late, but I hope someone has an answer to my question. What happens if you film with a zoom lens and the DOP zooms in the shot itself? The mm's differs, right? How do you make a distortion grid then?
Besides the great content (..BIG thx, Hugo!) - Bjorn is a real cutie! 😊
Haha, yes he is. He is also an amazing compositor.
@@HugosDesk He must have watched a lot of Hugo's desk then ;-)
Hello, one quick question I had while watching the clip. What is the merit of using the distortion grid with xo in the center?
It's not mandatory but I find the cross easier to line up the camera with the grid at perfect 90 degrees on both vertical and horizontal axis. And the inner smaller checkboard is very useful if you have a telelens above 100mm. Hope this helped
@@HugosDesk This helped me tremendously. Thank you. I also had another question if that is possible. Do you have any tips for shooting a lens distortion grid for a zoom lens?
awesome bro, you think shooting a distortion grid displayed on IPAD would work?, i dont want to carry that huge board!
Wondering how important the size of the grid is? Eric Albas pdf's are 8ft by 4ft, yours looks much smaller, hard to tell but possibly 5ft? Have you run into any limitations using the smaller (more practical) size?
We did small because we could get a bigger one at the time for the video. But the size is linked to how wide you are filming. It needs to be big enough to cover the entire lens and still be in focus so the wider you are the bigger it will be. Eric’s size is the perfect size to cover any lens you have from a 12mm to anything in between. If you for example only have a 35 or a 50 as the widest then the grid can be relatively small.
@@HugosDesk Thanks for the speedy reply, that's incredibly helpful!
@@HugosDesk If we are shooting with a zoom lens, is the lens distortion the same if we are zoomed in or zoomed out on the lens? If we shoot wide and we zoom in to cover the printed grid, would that work? Thanks for your time
.
@@ChrisGunningham-t1x With a zoom lens you would have to film several focals of the lens to cover distortion in the entire lens. I would recommend going step by step and filming as many locals as you filmed. Most lenses these days can do metadata so you could find out what focal was used. Filming all locals is crucial for the 'lens focus breathing'
Thanks Hugo
@@HugosDesk
AWESOME explanation your stuff is always so deep it can be hard for a hobbyist to follow. Couple of questions:
1. How punishing is it to do the distortion grid AFTER alot of compositing has been done?
Convincing non-VFX people that prep like this has to be done seems like a hard social aspect. For a big production i'd assume there'd be tech days scheduled but for smaller amateur stuff probably not.
2. How does getting time with camera+lens typically work out? (I mean it doesn't seem non-trivial convincing someone to either give you their gear, or make them show up early,or stay late )
#2 kinda answered in Chris Struber
's question here: th-cam.com/video/LsoaGOd-NB4/w-d-xo.html&lc=Ugyh1UjJEfV-a9JvkqB4AaABAg
Thanks so muhc for watching and for the kind words regarding my video.
Regarding your first question, not sure what you mean about 'social aspect'. In a VFX house lens distortion is part of the pipeline, it is essential and necessary. It is not an option. We work in accuracy and photorealism.
Regarding number 2, this is normally part of the shoot's schedule. I always talk with production and the 1st AD and we decide together when is the best time to make this happen. I have also done it back at the rental house a few times. That also works.
@@HugosDesk For the social aspect I mean like says it's an indie production and no one is used to VFX so different departments have to be convinced/educated to get time with different equipment.
I understand that solving the lens distortion needs straight lines, but do they actually need to be level in frame? Is there any downside if the grid is rotated?
Well, the straighter it is the easier it is for the software to calculate an accurate lens map. It will probably work just fine without levelling but I tend to make sure it is as perfect as possible.
@@HugosDesk makes sense that nuke is tuned to detect horizontal/vertical lines. So shooting it level should save a lot of manual work drawing lines. I appreciate the quick response!
Absolutely, specially because Nuke’s auto grid never works so I always tweak the lines by end! Always!
Would it be good to rent cameras to pre film grids and build a library of lens grids?
Should I distort the full image later or rendering it undistored is better?
The correct workflow is:
Undistort Footage -> track shot -> use the original Footage -> add CG elements -> redistort only the CG elements
The undistortion of the footage is only for tracking not to use.
There is one exception. If you need to move the plate in the frame or scale the plate, for example, a green screen plate of someone that needs to be smaller in the CG environment, then you should:
Undistort Footage -> scale/reposition shot in the CG -> redistort everything
@@HugosDesk Thank you!
@@mikego2611 NP
so you do all this so you can help the tracker? and then put the lense distortion back on the final composited image??? did i understand correctly ?
Hi, first off, VFX is a team effort, so yes I do "all of this" to help my 3D tracking team. Second, any CG, Matte painting elements that will be composited to a plate of live-action needs to have the same distortion. So you need to 'redistort' all the elements before compositing any of them on top of your footage.
Hugo's Desk thanks Hugo for these amazing tutorials
Hi, is that ok to shoot the grid with different camera but with same lenses?
Not really because the sensor of the camera makes a difference on the focal and size of what the lens sees!
@@HugosDesk oh got it. btw thank you so much for the quick response...
Please make one video on camra seting on set... ♥️📹
How to cculate lens destortion in equilizer? Please tell me.
Sorry I don’t use Equilizer. Maybe check FXPHD?
Thank you
Whenever you could please make an example of anamorphics lens and theirs diferences.
Hi Hugo, what size did you print the grid? It does not look like 2m x 1m, is this size mandatory? thanks
I printed a smaller one this time because I only had to film one lens for this show I was filming at Sony. It needs to be big enough for the widest lens you have with the sharpest possible image. So if you point your camera and the widest lens to a wall, find the closest sharp position from the wall, just measure the limits of the screen and that is the size you need.
@@HugosDesk perfect explanation hugo. I sent to print a 1.20m x 60cm. My widest lens is a 24. I think I will be fine. Thank you man you rock
@@HugosDesk One more question. How is in the case that I have a 16mm but as I use the bmpc 6k is super 35mm. So the 16mm would end up being a 24. The true number would be de 16mm or 24 because of the sensor crop? thanks
thank yoooouuuuu
Noooooooo problem!
What leveling app did you use on the Iphone?
It’s called Clinometer + bubble level by Peter Breitling apps.apple.com/gb/app/clinometer-bubble-level/id286215117
If WE WANT TO PRACTICE IT , SO HOW DO WE GET THE LENS DISTORTION CARDS and please tell me at this point i am right or not , lens distortion is used so that we get proper tracking data , and the 3d objects we will place while compositing doesnt get strecht or distort ?? am i right or not ! please help me by replying! and i also want the nuke manual do read from where do i get that ?? btw thanks
Hi, yes you are correct. Regarding the Nuke Manual, it’s included inside Nuke. Just go to the help tab and select help. It’s all there. Thanks for watching
where do you buy one of those lens grids tho
You can’t really buy them. You usually need to print them on demand for the project since they can’t be curved by humidity or wrinkled by time. I have some links on the video description for the instructions
Did not watched the video yet but is lens distortion not dependent on the distance betwen the lens and the talent/object you film ? And then how many lens distortions profiles you make ?
Maybe you should watch first and then ask questions?
And btw these some extra information on the description including documentation from VFX supervisors.
Did not finish reading your message but I can you're an idiot.
Is there a way to solve the grid in Fusion, Blender or a free software?
How do you do a lens grid for a zoom lens?
Well, most VFX productions are filmed with Primes but if you read the documentation on the links you can see that filming a zoom lens is the same as filming several lenses. You need to film the grid at several focal. Example if the zoom is 24-105 then you film at 24, 35, 50, 85 and 105. You just have to film several grids to 'map ' the different distortions of the zoom.
How can you do this in Natron?
Not sure! Does it have a lens distortion node? You can do it in Nuke Indie or Nuke Non Comercial!
does focus change the distortion of a lens?
To correctly 'map' the lens distortion you need to be pretty sharp when filming the grid. So a high Fstop and pulling focus to the grid. Taking a few grids on lower f-stops matching the plates could be a good reference for aberration but it won't helo the mapping of the lens.
Where can I purchase lens grids?
You need to print them! Use the links and instructions on the description. Thanks for watching
@@HugosDesk Cool, thanks for replying!
Is there a such thing as a portable lens distortion grid.
What if your client doesn't give you lens grid? How do you figure out distortion?
You can calculate them in a tracking software
and thanks for your friend
What is the best way to launch a nuckear missile from outside the silo, overriding military control?
?????
I know a guy who can help you. His name is Bond. James Bond
I just need an address to give him so he doesn't get lost.
@@insanejughead - Forget Bond. He always gets lost, even with an address and a flashing goalpost. He is British. Just look up Brexit. The Brits are all like this. That's why they lost their Empire. Now they are even losing their own country.
No, I need someone like Kevin Mitnick, not like Bond.
@@HugosDesk - Missile silo. Missile, launching it from outside by remote.
Which letter is it you do not understand?
.Sir please make a tutorial undistort a short using 3DEqualizer, and add 3d elements and composite in nuke, if it is exist reply the link. I will be most thank full to you.
you just have to be better at explaining the workflow when the undistorted image is now beyond the bounding box, because when the distortion is reapplied to the final output everything you composite in-between will be missing at the edges. I know, but it can be a real headache if you dont.
You are a funny guy! Haha. You know I actually recorded that part and I removed it because I thought it may confuse people. I think that is beyond the scoop of this video. This video is about filming the grid the grid itself. But it is simple, just increase your canvas using a reformat. If you add pixels around your image without scaling then you grow your edges. If you want come by my Twitch Thursdays streams and ask that on the chat and I can shot it live. Thanks for watching
Btw this is all covered on my online Nuke course on Kickstarter. Thanks
@@HugosDesk where exactly? I want to learn that bounding box thing at all costs
@@HugosDesk there are 2-3 composting course, which one has this bounding box thing included?
How do account for Zoom?
Well, most VFX productions are filmed with Primes but if you read the documentation on the links you can see that filming a zoom lens is the same as filming several lenses. You need to film the grid at several focals . Example if the zoom is 24-105 then you film at 24, 35, 50, 85 and 105. You just have to film several grids to 'map ' the different distortions of the zoom.
@@HugosDesk That sounds like a pain in the ass.
Haha, welcome to VFX!
Nice Info..You're God
Thanks mate but no I am not. Haha
whoa
Thanks