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What is the difference between a NURBS-Model and a Polygon mesh?
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- เผยแพร่เมื่อ 15 ส.ค. 2024
- NURBS and Polygon modeling is used to represent an object’s curves and surfacing using computer graphics software. The difference between these two models is how the computer calculates and presents the 3D image. Learn more at: holocreators.c...
NURBS and Polygons interpret data differently to create a 3D model. NURBS modeling uses lines, or vectors, while Polygon modeling uses a mesh of triangles. I made one mistake in the video, whenever I talk about voxel graphics I actually meant vector graphics. Otherwise it's all correct.
Project files:
Polygon Mesh Example (STL):
www.dropbox.co...
3D Viewer Meshlab (free software):
www.meshlab.ne...
NURBs model Example (STEP, IGES, X_T):
www.dropbox.co...
FreeCAD (free CAD software):
www.freecadweb...
Timestamps:
00:00 Introduction - Two kinds of 3D models
00:11 NURBS & Polygon models
00:40 What’s the difference between the two models
01:20 Pixel graphics
02:20 Vector graphics
About Holocreators:
Holocreators is a 3D-Scanning and Reverse Engineering Company. We'd love to help you with your projects. Please call us +49 40 481133 or write to us an email.
Email: info@holocreators.com
Website: holocreators.com/
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Hashtags:
#nurbs
#pixelgraphics
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Image Source Thumbnail:
(Versus) www.freepik.co...
(Explosion effects) www.freepik.co...
I made a mistake in the video, whenever I talk about voxel-graphics I actually meant vector-graphics. Otherwise it's all correct. Have a great day! If you would like to learn more about the NURBs-Modeling or Polygon mesh modeling, check out our website: holocreators.com/blog/what-is-the-difference-between-a-nurbs-model-and-a-polygon-mesh/ Holocreators is a 3D-Scanning and Reverse Engineering Company. We'd love to help you with your projects. Please call us +49 40 481133 or write to us an an email: info@holocreators.com
I thought it was odd how only the subtitles were correct lol
Thanks for the explanation. Really helpful.
thank you :-)
This was so simple and clear. Thank you very much
Thanks Göker, video is about 2 years old, and I would explain it a little different today, but basics still hold up. Have a great day.
Спасибо, очень ясно и доступно. Thank you, very clear and accessible.
Thank you :-)
So the analogy of NURBS & polygons in 2D design is:
*NURBS models = vector graphics / polygon meshes = pixel graphics*
Vectors/NURBS are _non-rasterized_ paths whereas pixels/polygons are _rasterized_ images
Or in the most general lingo-Illustrator vs Photoshop
sounds good
Thanks for the explanation
It was really helpful! 👍
Glad it was helpful!
What is the difference between a vector and a voxel model ? What does voxel mean ?
Btw thank you for the video, it makes it clearer !
that was a mistake I made. I ment vectors.
What's a patch? NURBS have different types of control handles right? Do they have different names for different manipulation types i.e. like simple points or handles like typical bazier curve?
i think they are all called nurbs patches, idenpendently of the manipulation style
It seems you say voxel graphics, but mean to say vector graphics. Voxel is the volume/3D equivalent of a pixel.
yes you are correct, I do mean vector graphics, I meant to rerecord the video at some point
I think the comparison for polygons is more like lines vs. curves, not pixels vs. vector graphics. Polygons are vector graphics. They're just ones formed by straight lines. They have infinite resolution just like a curve, but limited to straight edges. Pixels and voxels are discretized and have finite resolution in ways both polygons and NURBs curves do not.
that might be the better analogy, thanks
@@HolocreatorsCheers and apologies for my pedantry! I work as a VFX engineer and it is a popular marketing slogan to advertise voxel applications as having "infinite resolution".
But from my perspective, voxels are the epitome of finite resolution and prone to issues similar to aliasing with pixels. We can zoom in and start noticing "chunkiness". So I think the artists and animators are referring to "resolution" in the sense of "topology"; in that sense, voxels have no topological constraints.
Yet I think of "resolution" as a factor of rasterization or raytracing, so actually polygons have infinite resolution as well as NURBs patches and so forth and have parallels to 2D vector graphics (ex: Illustrator), while voxels have finite resolution and parallels to pixel/raster graphics (ex: Photoshop).
1:22 pixel and voxel graphic ^^
yes, please take a look at the description and comments. known about that for some time. otherwise the video is correct.
Thanks for this. one thing: You mentioned the advantage of the NURBS model being that it scales well. But what are the advantage(s) of the polygon model?
I often wonder why a 3d program can't combine the advantages of both the NURBS and polygon models.
Thanks!
Hi Kurt, good question. I don't really have answer for that. Maybe ask Chat GPT :-)
From a dev perspective, polygons -- more specifically triangles -- can be directly rasterized or raytraced. NURBs patches have to be converted into triangles before they can be rasterized and, while hypothetically a raytracer might be able to perform a ray/patch intersection, it's generally still cheaper in a raytracer to convert the patches to triangles first.
NURBs are also a bit finnicky both for programmer and user. They're very popular in CAD/CAM but they require more intricate knowledge about geometric continuity and degree, knot vectors, isoparametric curves, etc. Polygons are dumb simple and easy to program for developers and easy to understand for users and don't require any calculus.
There's also something of a blend in between with subdivision surfaces, like Catmull-Clark subdivision, where your polygon model effectively gets turned into curved patches with their edges effectively turning into b-splines. There's some extra complexity involved there though -- not quite as much as with NURBs -- but most subdivision schemes don't have things like extraordinary vertices very well.
Can you use Nurbs models in games? Can they be used for character animation in said games?
i would recommend polygons for that
@@Holocreators Thanks for your suggestion
Thanks. Very helpful!!!
glad it was helpful
Thank you for categorical explanation, i really needed it. Ok so lets speak of this in term of production and machining… what would be the differences?
well with a nurbs model you should get a smoother machined part. But I am really no expert on this.
so are they made of the same components?
sorry i dont understand the question
I want to model a car. Currently i use AutoDesk maya to model. What other software should i use to create car. I was thinking about AutoDesk alias, will it work.
Maya is great for modeling cars. NURBs modeling is the way to go for car modeling. Good choice!
You could also try Blender 2.8x... very good vor modeling...
Dont forget rhino… many cars makers use it too
Alias for Nurbs, Blender for SubD, GravitySketch for sketch modelling
I had no idea about nurbs could a game be made? it would obviously be pretty basic since I imagine it is very computationally inefficient but I see no reason you couldn't
Hi, a game with Nurbs models? I suppose you are thinking about a retopology with quads. That's a little different process. Quads will not scale in the same way that nurbs can. So a quads model will look jagged if you make it bigger and bigger, of course you can then subdevide it but thats a different story.
I think you could make that reasonably efficient now with hardware dedicated to dynamic tessellation for rasterization (assuming rasterizer rather than raytracer which is getting popular nowadays with RTX), but it doesn't make so much sense to me unless your engine does some in-game effects that benefits directly from NURBs splines or a level editor that provides NURBs-based modeling since you can represent the same forms using much more compact representations (ex: patches using curves other than NURBs curves which are quite heavy, like quadratic bezier curves which are much lighter). Also all the other things a game needs to do besides rendering becomes more much involved computationally (ex: physics) with NURBs patches.
What about T-Splines vs Nurbs?
T-splines are just a type of NURBs surface. Same principals apply.
thanks for the subtitles
Thank you. Putting subs on all our videos was a lot of work. Really happy if they are used. Also I corrected some of the incorrect wording I used in the video, so the subs are actually more accurate then me talking. Maybe you should just switch of my voice :D
@@Holocreators Yes, they really helped. My native language is not english so i could use them to better understand you
@@slavik5932 thats good to hear. have a wonderful day.
Thanks / Really helpfull
thank you
Is this like the cad modelling in fusion 360 ...
Why this process isn't used in films and animation
Please reply me
Hi Swapnanil, In CAD (Fusion 360)you can do Solid modeling or Nurbs Modeling. Depends on the application. Did I understand your question correctly?
Thank u so much for your quick reply
But I wanna ask that question , I am actually an animation student and I asked it to my teacher , but I wasn't happy with that foggy answer
I just wanna ask you why in films , VFX , or animation we use polygonal modelling all that time I think it's good for organic modelling and some other area
But if we use this cad type or mathematical type of modelling to model some hard surface or like pistal , cup, teapot, solid pieces of mechanical parts can not be it helpful ... Beacouse no need to take hedech of heavy numbers of polygon
I can remember some months ego my Iron man mask modelling in 3DS Max ...
And some days ego I saw some one did the same thing in solids works with some simple curves, it was so time consuming ...from that i am thinking about that ...
I don't know if I could make u understand.
But will be really happy if you kindly answer again
(And sorry if my English wasn't fully correct ... And can I connect you in Facebook ??
Thank you
@@swapnanilnag3713 Hey. There is a few types of modeling. 1. There is CAD modeling where you create solid models with sketches and extrude ( example Fusion360). 2. There is NURBS modeling where you create NURBs models with curves ( example Fusion360 & Blender). 3. There is polygon modeling with triangles or quads ( example Blender).
So Fusion360 can do Solid modeling and NURBs modeling
And Blender can do NURBs modeling and polygon modeling
you can add me on facebook. its swann manuel
@@@Holocreators thank u sir for sharing your knowledge with me ...
@@swapnanilnag3713 sure thing. happy to help :-)
why nurbs not used in games! for like the circular simple shapes, it does not work in game engines ?
good question i don't know
because the GPU is more efficient at calculating the position and behavior of polygons, especially in large quantities. This isn't the same for dealing with NURBS.
@@ashfordnichols3622 thanks. that makes sence.
NURBS model needs to be tessalated before displaying onscreen. So it is used mainly for precision work such as CAD. A good NURBS + Polygon combo is Rhino + Blender though.. here's a demo : th-cam.com/video/n9zMxUOD3CU/w-d-xo.html
Efficency wise, Polygons are less resource consuming to compute and apply any type of PP filtering than nurbs. The same figure, lets say for example, a teapot with a very easy shape, can be easily x10 heavier with resources when modeled with nurbs that with simple polygons depending in the software you use.
You may end with exactly the same results, form wise and aliasing wise but the processing unit (either cpu or gpu) will have to calculate more quads or tris when doing nurbs in a cad system to have an easier predefined fidelity into the 3d model, that is why software that does mesh based modeling such as blender has a lot of tools for rendering and PP, instead of 1000 quads to process you might end up having 100 depending in the complexity of what are you doing and then applying mathematical technics within the software to simulate smoothed surfaces and refractions that take way less time and resources.
However, this might not be the case always, I've seen models made with nurbs that have some really nice meshing that would allow the same strategies to be applied in other software.
Im speaking from my experience as a drafter that use Solidworks both for mechanical engineering and game design wise.
Thank you :)
Thank you!
it's like svg vs jpg
ok
they're the same
i dont think so.