Hi, thanks for the video, in the step of selecting the bursts for the split it can be done using the user interface, it is not intuitive but you can click and hold the arrows on the bar just abobe the preview image, and drag them and that way you can select the from and to bursts in the graphical user interphace.
In my opinion, any date between 24th september and 6th october, topography usually didn't change so much over short period of time, unless there are massive natural disaster in the area such as earthquake or landslide.
Hello! Is there any way to make a DEM without using Range Doppler Terrain Correction? ( I´m working with mines, so, every time I realised the Range Doppler, it takes some old reference points in the middle of a Cave/Open Pit Mine ( that does not exist anylonger there) and destroys my DEM ? (It sometimes mekes a hill in the middle of a pit cave of 1000x1000x250m )
Hello Can you help me actually I am doing a project on Large-scale building height retrieval from single SAR imagery based on bounding box regression networks For this I am not getting the dataset can you provide me with the dataset and also tell me how to move further into the project
Large scale building retrieval needs super fine SAR Imagery in 0.5 meters resolution or finer, that kind of data currently only can be obtained from commercial SAR imagery vendors such as UMBRA or some others, I also would like to get access to that kind of data for free if it is possible. I am not a millionaire ya know.
Hello..thanks for sharing this video. So I am facing a problem in creating g Orb file. It shows: Type: Operator Exception Message: Java.io.IOException:XML document structure must start and end within the same entity. Please tell me how to fix it. Thanks
check this thread from ESA SNAP forum forum.step.esa.int/t/error-nodeid-apply-orbit-file-xml-document-structures-must-start-and-end-within-the-same-entity/22502/6
There is none as far I know, but for more specific interferometry application like insar deformation, or land subsidence there are some, Thematic Exploitation platform from Terradue is one of them. However most of them are not free
Hi, i would like to ask. Why i can't do SNAPHU unwrapping? There's only 2 choice of the unwrapping which snaphu export and snaphu import. And i cannot find snaphu unwrapping. I also already followed each step of this tutorial
Hi, thanks for the video. I have followed all the steps but in the DEM image there is much noise looking on it. Is there any additional step to be performed?
can you confirm that the noises correspondence with vegetated area?, if it is yes, then nothing you can do, because that is the limitation of sentinel-1 interferometric DEM processing, you can refers to SAR interferometry theories for further explanation,
Water is also can't be solved, urban area commonly have a good interferometric coherence due to its static appearance in the imagery. Good coherence will guarantee a good DEM result, but urban area just like its name suggest, usually have a lot of small size settlements and building with various height characteristics, so in the DEM result this characteristics will cause height noises. This would be different if you are using high resolution SAR like terrasar-x or cosmo skymed, the DEM result in urban area would be better.
@@GEO2004 Thankyou so much for the clarification. Actually I was stuck in determining the flood depth using Sentinel-1 data and DEM was required in that. If you know about how to determine flood depth with Sentinel-1 SLC data, please tell or please share any tutorial or video if you have.
You must do field survey for this matter, dem from sentinel-1 won't helps at all because sentinel-1 actually is not designed to provide good DEM data, sentinel-1 is only quite good to map the flood extent, but not flood depth
Hi. Why you used two sentinel images products and applied the same process in the two, I just have one product file, do I need to use two, what is the purpose of that, please
Yes you must use at least two imagery covering same area. Why? Because it is using interferometric principles. You can read and dig about it if you want to know more, Explaining here would be just too long and too complex if you are not understand even the most basic understanding
Yes to some degree, as long as no vegetation jn the image coverage, and the baseline length between image pair is more than 150 meters, there is possibility a dem can be generated
Hi izin bertanya 11:59 , kenapa pada pengolahan saya tidak muncul notif seperti pada menit terusebut? Dan output produk nya tidak muncul? Mohon jawabannya untuk skripsi saya🙏
Kemungkinan proses unwrapnya tidak benar atau inteferogramnya sangat jelek sehingga unwrapnya tidak berhasil. Interferogram jelek ditandai dengan tidak adanya pola pola fringe yg unik dan hasil inteferogram jelek lebih kayak random warna pixelnya seperti siaran tv yg tidak daapt sinyal, layarnya cuma kayak semut2 bertebaran hehe
Betul, interferogram yg saya hasilkan, tidak seperti warna pelangi di video, namun lebih seperti siaran tv rusak. Apakah ada solusinya untuk itu? 🥹🙏@@GEO2004
@@GEO2004 iya memang betul interferogramnya tidak seperti pelangi seperti di video, namun seperti tv tidak ada sinyal, jika interferogram nya jelek apakah ada solusinya? Terimakasih..
Tidak ada solusi, karena selisih waktu perekaman antar citra cukup lama, apalagi kalau penutup lahannya banyak vegetasi, kalau mau lebih baik hasilnya, cari lokasi yang tidak ada/minim vegetasi
SLC (single Look Complex) commonly refer to SAR data in single look resolution (slant range). SLC data still have the original geometry when the data is recorded. SLC format is also store SAR backscatter in its original form (imaginary and real number), it is still maintain the radio wave phase information (not only the intensity and amplitude information). GRD (Multi Look Ground) commonly refer to SLC SAR data that has been resampled to ground range/multi look, it have same pixel size in X and Y direction (like commonly found in Optical Imagery). GRD data usually have lost its radio wave phase information so it cannot be used in Interferometry (however it is still can be used for Radargrammetry).
I am working on land deformation of SLC product of sentinel 1 data but getting error while exporting in PSI . I followed all steps correctly but again its showing do interferogram and co-registration of product please products help me out thanks in advance
Precisely, I don't know for sure. This is actually a research question that only can be answered by experiment. however Based on my current understanding, it will improve the accuracy until the output spatial resolution of the SAR data limiting the vertical accuracy to its maximum allowed possible accuracy (you can't expect 0.5 meter vertical accuracy on 15 meters resolution in hilly terrain)
@@GEO2004 When using external DEM, I notice in the create interfergoram, the parameters will default to SRTM3sec. In order to use external DEM I need to activate the Substract topographic phase option. Is this the right thing to do? And theres option to check for earth gravity model as well. which is confusing too.
Dear sir, I encountered error when I applied Enhanced Spectral Diversity as following: A problem occurred during the target product processing. Type: OperationException Message: Java heap space (I am using SNAP 9) so I skipped this step (I used only one burst) Finally, I got two elevation results: elevation VV and elevation. So elevation VV is from Sentinel 1 and elevation is SRTM 1arcsecond, rights? And when I exported the result into tiff format, the resulting tiff file has two bands. So the band 1 and band 2 are elevation VV and elevation, respectively? And I noticed that band 1 is extremely different from band 2 ( for example: -169m vs -6m) . And if compared to SRTM 30 meters which I downloaded separately, band 1 result is also extremely different (too high max and too low min). I don't expected too much different between them even though there are several limitations of DEM from Sentinel 1, maybe I did sth wrong? (The used pair images has perpendicular and temporary baselines are -58m and -6 days, respectively). Could you please let me know how to address these problems? You help is extremely important for me and much grateful for that.
1. Yes, you are right 2. Yes you are also right about tiff output 3. That is inenvitable, basically sentinel-1 is not designed for insar DEM extraction (it is using C-band with quite a long temporal difference/six days in equator), after all insar also depends on line of sight constructed from baseline length (sensor distance between acquisitions), so those height differences are expected. Sentinel-1 radio phase also not free from ionosphere and troposphere effects, and those effects will tremendously affect the accuracy of phase extraction information. Snap 9 have some new features for interferometry like ionosfer correction and bandpassfilter, personally I am excited if those new features will improve the insar DEM extraction or not, I have a plan to make a video about it if those new features are really promising. In the mean time, what about you learn it first?. May be those new features could improve the DEM result. One more thing, if your application only needs height differences instead of absolute height, I guess you can ignore those absolute height differences between datasets and just focusing on using relative height obtained from the elevation_vv data.
@@GEO2004 Dear sir, thank you so much for your comprehensive explanation. Actually, I need absolute DEM value. If as what you mentioned above new features that could improve the DEM, I will look forward to your next tutorial on that and also check it myself if I have time. However, I have limited time and need to decide whether to use open source DEM 30 meter (like Alos) for my study. Will also appreciate it if you can recommend me any open source data for my study area that I want to study about urban flood. Again, really appreciate your kindness.
as far as open source data available for public, I think other than already available public DEM in 30 meters (copernicus dem, nasa dem, srtm, alos world 30 etc), higher quality and higher resolution data can only be provided from national data repository, and every country in the world (developed or developing countries) should have one, I guess maybe you can try to look the data for your country first.
Ascending or descending doesn' matter, the most important thing is not mixing up the descending and ascending images Baseline length is not specific for any country, good baseline length is between 150-500 meters
@@GEO2004 i finally found the problem. With same satelite image, time but different site for download it. When i download from alaska it got problem like that. But when i download from copernicus, finally it worked. Thnks
You should learn first about sar interferometry theories, keep in mind that if you learn about remote sensing, just dont forget about the concepts and theories.
If there is no vegetation on the area, I am sure the accuracy is quite good. The one factor that remain need to be resolved is the atmospheric disturbance to the radar signal, that yeah you are right, one solution to overcome this atmospheric effect is only using n-pass interferometry
Izin bertanya mas, berarti untuk bisa diolah ini berarti harus dengan dua citra yg memiliki sudut tangkapan yg berbeda ya? Cara mencari nya bagaiamana mas? Untuk mendapatkan dua citra yg berbeda sudut trsebut? Mohon bantuannya mas 🙏
Kalau uda acer download data sentinel dari portal ASF, disana ada alat untuk memilih citranya berdasarkan sudut dan jarak tangkapan, namanya ASF baseline tool, nanti kalau ada waktu coba saya buat kan video tutorialnya
@@GEO2004 Terimakasih sblmny mas Saya saat ini sedang melaksanakan penelitian untuk skripsi tentang perubahan topografi di salah satu gunung vulkanis, dan PKL di badan informasi geospasial di Bagian PPIT. Dari video d yt ad video d bogor, apakah mas juga bertugas di BIG? jika iya saya berencana juga hendak belajar langsung, khususny tntng interferometri ini Kira2 apakh bisa itu mas?
@@GEO2004 izin bertanya kembali mas, mohon bantuannya 🙏 untk arah penerbangannya jika ascending brarti pasangan citra nya juga harus ascending kan? Tidak match jika ascending dan descending
Your result cant be avoided and that is the common result if you are using sentinel-1 data for your dem interferometry, here are why: 1. Sentinel-1 is a C band SAR. Radar at C band, X band, even L band cant penetrate the landcover, so significant temporal differences will resulting in failure interferogram generation (due to low coherence), that is because the landcover of the master and the slave images has been changed. Then may be you asking why my result is quite good?, .my result is good because I am using imagery that covers desert/arid region which mostly didnt have vegetation cover, so the landcover condition is not changed between the dates, I can get a good coherence and upmy interferogram can be formed 2. The only way to get a good DEM from C-band or X-band SAR sensor is the master and slaves imagery temporal differences should be as short as possible (even few hours differences cant be accepted, it should be in seconds or minutes), that is also explain why SRTM which is also using C-band bring two SAR antennas, it is designed to make the temporal differences is super short, and Sentinel-1 isnt.
@@GEO2004 how is it possible to obtain measurements to the millimeter to monitor, for example, bridges? see the research "Displacement monitoring and modeling of a high-speed railway bridge using C-band Sentinel-1 data"
It is possible because theoretically radar backscatter phase is so precise and accurate (gps technology is also using wave phase measurement to determine location), The problem is, SAR phase measurement is heavily depended on many factors. For example, SAR based displacement measurement is considered as LoS (line of sight) displacement. Different incidence angle of SAR measurement will resulting different displacement result. There are also components in SAR displacement measurement, vertical and horizontal component. They are adding the complexity. This is why single interferometric displacement measurement wont gave accurate displacement rate. To overcome this, SAR based displacement measurement employ Persistent scatterer interferometry technique. It is a technique to monitoring the height difference of certain object (such as bridge) over a very long time. So it is will cancel out or generalize the variance between measurement, and average displacement rate measurement result can be obtained with a higher degree of confidence.
a short tutorial about tips and tricks to properly select SAR imagery pair for interferometric processing : th-cam.com/video/2TxAXYSDyYQ/w-d-xo.html&lc=UgylMg3yKZEyAut9uWN4AaABAg
halo, izin bertanya ketika saya di tahap snaphu unwrapping kenapa setelah 9% ilang begitu saja ya? tidak ada notif tidak ada apa-apa. Filenya ada namun tidak dapat dimasukan ke app SNAP, mohon pencerahannya jika ada
Download Various SAR data and imagery for free, check this link : th-cam.com/video/sNLqD7f6fhU/w-d-xo.html
Thank you very much. I just discovered your video. Very successful. I applied it exactly and got the result I wanted. Thank you.
Nuevamente veo tu video y no tengo más que agradecerte por tu gran trabajo, saludos desde Ecuador
muchas gracias
Hi, thanks for the video, in the step of selecting the bursts for the split it can be done using the user interface, it is not intuitive but you can click and hold the arrows on the bar just abobe the preview image, and drag them and that way you can select the from and to bursts in the graphical user interphace.
I dont know, sometimes selecting bursts is not work for some SNAP installation, thats why I go with safer workflow
Hello, Data dated 2019/10/06 and 2019/09/24 were used for DEM formation. What is the date of the created DEM data? Thanks.
In my opinion, any date between 24th september and 6th october, topography usually didn't change so much over short period of time, unless there are massive natural disaster in the area such as earthquake or landslide.
Thank You Very Much for the tutorial.
Glad it was helpful!
Good job
Hello!
Is there any way to make a DEM without using Range Doppler Terrain Correction? ( I´m working with mines, so, every time I realised the Range Doppler, it takes some old reference points in the middle of a Cave/Open Pit Mine ( that does not exist anylonger there) and destroys my DEM ? (It sometimes mekes a hill in the middle of a pit cave of 1000x1000x250m )
what about using SAR simulation terrain correction? it is not as accurate and precise as range doppler, but maybe can solve the DEM errors
Hello
Can you help me actually I am doing a project on Large-scale building height retrieval from single SAR imagery based on bounding box regression networks
For this I am not getting the dataset can you provide me with the dataset and also tell me how to move further into the project
Large scale building retrieval needs super fine SAR Imagery in 0.5 meters resolution or finer, that kind of data currently only can be obtained from commercial SAR imagery vendors such as UMBRA or some others, I also would like to get access to that kind of data for free if it is possible. I am not a millionaire ya know.
I want method display Minerals under The earth's surface
Hello..thanks for sharing this video. So I am facing a problem in creating g Orb file. It shows:
Type: Operator Exception
Message: Java.io.IOException:XML document structure must start and end within the same entity.
Please tell me how to fix it. Thanks
check this thread from ESA SNAP forum forum.step.esa.int/t/error-nodeid-apply-orbit-file-xml-document-structures-must-start-and-end-within-the-same-entity/22502/6
Very nice tutorial. Mau tanya, study area saya berada di IW1 dan IW2. Cara merge nya gimana ya pak? Thanks
Bisa di merge pake TOPS-Merge
Thanks for the nice video. Is there a cloud-based platform for generating DEMs from Sentinel-1?
There is none as far I know, but for more specific interferometry application like insar deformation, or land subsidence there are some, Thematic Exploitation platform from Terradue is one of them. However most of them are not free
@@GEO2004 thanks
Thnaks...Great video💖💖
You are so welcome!
what is the baseline criteria for making DEM from a pair of S1 image plz explain
here is a guideline th-cam.com/video/2TxAXYSDyYQ/w-d-xo.html
Really Thanks. Well done
Hi, i would like to ask. Why i can't do SNAPHU unwrapping? There's only 2 choice of the unwrapping which snaphu export and snaphu import. And i cannot find snaphu unwrapping. I also already followed each step of this tutorial
You must install snaphu first from plugins menu
Hi! For me unwrapping only worked this way :
th-cam.com/video/By6wo0a6xQk/w-d-xo.html
Hi, thanks for the video. I have followed all the steps but in the DEM image there is much noise looking on it. Is there any additional step to be performed?
can you confirm that the noises correspondence with vegetated area?, if it is yes, then nothing you can do, because that is the limitation of sentinel-1 interferometric DEM processing, you can refers to SAR interferometry theories for further explanation,
@@GEO2004 thanks for the reply. Most of the part corresponds to vegetation but urban and water regions are also there.
Water is also can't be solved, urban area commonly have a good interferometric coherence due to its static appearance in the imagery. Good coherence will guarantee a good DEM result, but urban area just like its name suggest, usually have a lot of small size settlements and building with various height characteristics, so in the DEM result this characteristics will cause height noises. This would be different if you are using high resolution SAR like terrasar-x or cosmo skymed, the DEM result in urban area would be better.
@@GEO2004 Thankyou so much for the clarification. Actually I was stuck in determining the flood depth using Sentinel-1 data and DEM was required in that. If you know about how to determine flood depth with Sentinel-1 SLC data, please tell or please share any tutorial or video if you have.
You must do field survey for this matter, dem from sentinel-1 won't helps at all because sentinel-1 actually is not designed to provide good DEM data, sentinel-1 is only quite good to map the flood extent, but not flood depth
Excuseme, May I get the link to download the ArcMap, Please. Thanks in advance.
Sorry, I can't provide that because arcgis is esri's intellectual property, I think you can find it from google search,
Dear, when do unwarpping every time stop in 9% please support if can
this might be due to the interferogram quality is bad, so unwrapping found some unresolved calculation
@@GEO2004 Thanks
Hi. Why you used two sentinel images products and applied the same process in the two, I just have one product file, do I need to use two, what is the purpose of that, please
Yes you must use at least two imagery covering same area. Why? Because it is using interferometric principles. You can read and dig about it if you want to know more,
Explaining here would be just too long and too complex if you are not understand even the most basic understanding
@@GEO2004 so I can't create DEM if I'm not using two imagery
Yes
@@GEO2004 can I use the same iagery product twice just by changing the name so SNAP can accept it
Read first about interferometry brother. Don't be such an ignorant person. This is not good for your learning progress
Can we use Sentinel 1 A SLC IW for creating DEM?
Yes to some degree, as long as no vegetation jn the image coverage, and the baseline length between image pair is more than 150 meters, there is possibility a dem can be generated
Excelente
glad it was helpful
Hi izin bertanya 11:59 , kenapa pada pengolahan saya tidak muncul notif seperti pada menit terusebut? Dan output produk nya tidak muncul? Mohon jawabannya untuk skripsi saya🙏
Kemungkinan proses unwrapnya tidak benar atau inteferogramnya sangat jelek sehingga unwrapnya tidak berhasil. Interferogram jelek ditandai dengan tidak adanya pola pola fringe yg unik dan hasil inteferogram jelek lebih kayak random warna pixelnya seperti siaran tv yg tidak daapt sinyal, layarnya cuma kayak semut2 bertebaran hehe
Betul, interferogram yg saya hasilkan, tidak seperti warna pelangi di video, namun lebih seperti siaran tv rusak. Apakah ada solusinya untuk itu? 🥹🙏@@GEO2004
@@GEO2004 iya memang betul interferogramnya tidak seperti pelangi seperti di video, namun seperti tv tidak ada sinyal, jika interferogram nya jelek apakah ada solusinya? Terimakasih..
Tidak ada solusi, karena selisih waktu perekaman antar citra cukup lama, apalagi kalau penutup lahannya banyak vegetasi, kalau mau lebih baik hasilnya, cari lokasi yang tidak ada/minim vegetasi
What are the differences between S1-SLC and S1-GRDW
SLC (single Look Complex) commonly refer to SAR data in single look resolution (slant range). SLC data still have the original geometry when the data is recorded. SLC format is also store SAR backscatter in its original form (imaginary and real number), it is still maintain the radio wave phase information (not only the intensity and amplitude information).
GRD (Multi Look Ground) commonly refer to SLC SAR data that has been resampled to ground range/multi look, it have same pixel size in X and Y direction (like commonly found in Optical Imagery). GRD data usually have lost its radio wave phase information so it cannot be used in Interferometry (however it is still can be used for Radargrammetry).
I am working on land deformation of SLC product of sentinel 1 data but getting error while exporting in PSI . I followed all steps correctly but again its showing do interferogram and co-registration of product
please products help me out
thanks in advance
I am sorry, I never use PSI on SNAP processed data, usually I directly using stamps or other PSI software to do PSI/SBAS.
@@GEO2004 thanks
If we use a higher accuracy reference DEM for example from IFSAR or LiDAR, do u think it will improve the height accuracy of the resulting DEM?
Precisely, I don't know for sure. This is actually a research question that only can be answered by experiment. however Based on my current understanding, it will improve the accuracy until the output spatial resolution of the SAR data limiting the vertical accuracy to its maximum allowed possible accuracy (you can't expect 0.5 meter vertical accuracy on 15 meters resolution in hilly terrain)
@@GEO2004 When using external DEM, I notice in the create interfergoram, the parameters will default to SRTM3sec. In order to use external DEM I need to activate the Substract topographic phase option. Is this the right thing to do? And theres option to check for earth gravity model as well. which is confusing too.
No, external dem can be used without activate the substract topographic phase option,
At 14:07 in the video, I saw that the reference DEM you used is 3 Arc Seconds, and its resolution is 90m instead of 30m, right?
ah yeah, my fault, I should use the 1sec one, thank you for correcting
Dear sir, I encountered error when I applied Enhanced Spectral Diversity as following: A problem occurred during the target product processing.
Type: OperationException
Message: Java heap space
(I am using SNAP 9)
so I skipped this step (I used only one burst)
Finally, I got two elevation results: elevation VV and elevation. So elevation VV is from Sentinel 1 and elevation is SRTM 1arcsecond, rights? And when I exported the result into tiff format, the resulting tiff file has two bands. So the band 1 and band 2 are elevation VV and elevation, respectively? And I noticed that band 1 is extremely different from band 2 ( for example: -169m vs -6m) . And if compared to SRTM 30 meters which I downloaded separately, band 1 result is also extremely different (too high max and too low min). I don't expected too much different between them even though there are several limitations of DEM from Sentinel 1, maybe I did sth wrong? (The used pair images has perpendicular and temporary baselines are -58m and -6 days, respectively). Could you please let me know how to address these problems? You help is extremely important for me and much grateful for that.
1. Yes, you are right
2. Yes you are also right about tiff output
3. That is inenvitable, basically sentinel-1 is not designed for insar DEM extraction (it is using C-band with quite a long temporal difference/six days in equator), after all insar also depends on line of sight constructed from baseline length (sensor distance between acquisitions), so those height differences are expected. Sentinel-1 radio phase also not free from ionosphere and troposphere effects, and those effects will tremendously affect the accuracy of phase extraction information.
Snap 9 have some new features for interferometry like ionosfer correction and bandpassfilter, personally I am excited if those new features will improve the insar DEM extraction or not, I have a plan to make a video about it if those new features are really promising. In the mean time, what about you learn it first?. May be those new features could improve the DEM result.
One more thing, if your application only needs height differences instead of absolute height, I guess you can ignore those absolute height differences between datasets and just focusing on using relative height obtained from the elevation_vv data.
@@GEO2004 Dear sir, thank you so much for your comprehensive explanation. Actually, I need absolute DEM value. If as what you mentioned above new features that could improve the DEM, I will look forward to your next tutorial on that and also check it myself if I have time. However, I have limited time and need to decide whether to use open source DEM 30 meter (like Alos) for my study. Will also appreciate it if you can recommend me any open source data for my study area that I want to study about urban flood. Again, really appreciate your kindness.
as far as open source data available for public, I think other than already available public DEM in 30 meters (copernicus dem, nasa dem, srtm, alos world 30 etc), higher quality and higher resolution data can only be provided from national data repository, and every country in the world (developed or developing countries) should have one, I guess maybe you can try to look the data for your country first.
@@GEO2004 Very well noted with many thanks, sir. I will check it out. Have a nice day, sir.
while downloading do we have to take care of baseline and ascending or descending?
Absolutely
@@GEO2004 Please tell what kind of baseline criteria has to be followed for India. Which one should I choose aacending or descending?
Ascending or descending doesn' matter, the most important thing is not mixing up the descending and ascending images
Baseline length is not specific for any country, good baseline length is between 150-500 meters
I got stuck at apply orbit proces, the app said it cant conect to the sentinel 1. Can u help me pls, for this problem?
Have you check your internet connection is fine?
@@GEO2004 i finally found the problem.
With same satelite image, time but different site for download it.
When i download from alaska it got problem like that.
But when i download from copernicus, finally it worked.
Thnks
Hi I would like to ask? Is it necessary to have 2 sentinel images? Can I just use 1, to create dem for soil moisture for comparison with ndvi?
You should learn first about sar interferometry theories, keep in mind that if you learn about remote sensing, just dont forget about the concepts and theories.
There is a theoretical explanation why 2 images are needed instead of one
@@GEO2004 thank you for the replies. Really appreciate it
what about the accuracy of DEM?
creating DEM with just by one pair is not accurate
If there is no vegetation on the area, I am sure the accuracy is quite good. The one factor that remain need to be resolved is the atmospheric disturbance to the radar signal, that yeah you are right, one solution to overcome this atmospheric effect is only using n-pass interferometry
Can we validate this dem?
Sure, validation is necessary in research
@@GEO2004 Sir my doubt is the Dems which are generated using Sentinel -1 sar data , using SNAP SOFTWARE, can we validate them??
Izin bertanya mas, berarti untuk bisa diolah ini berarti harus dengan dua citra yg memiliki sudut tangkapan yg berbeda ya?
Cara mencari nya bagaiamana mas? Untuk mendapatkan dua citra yg berbeda sudut trsebut?
Mohon bantuannya mas 🙏
Karna saya pribadi masih belum terlalu paham interferometri ini
Kalau uda acer download data sentinel dari portal ASF, disana ada alat untuk memilih citranya berdasarkan sudut dan jarak tangkapan, namanya ASF baseline tool, nanti kalau ada waktu coba saya buat kan video tutorialnya
@@GEO2004 Terimakasih sblmny mas
Saya saat ini sedang melaksanakan penelitian untuk skripsi tentang perubahan topografi di salah satu gunung vulkanis, dan PKL di badan informasi geospasial di Bagian PPIT.
Dari video d yt ad video d bogor, apakah mas juga bertugas di BIG?
jika iya saya berencana juga hendak belajar langsung, khususny tntng interferometri ini
Kira2 apakh bisa itu mas?
@@acerminang1522 bukan, saya enggak di BIG
@@GEO2004 izin bertanya kembali mas, mohon bantuannya 🙏
untk arah penerbangannya jika ascending brarti pasangan citra nya juga harus ascending kan?
Tidak match jika ascending dan descending
I am really interested in your video and I follow my results are fail
I cant help if you are not describes your error
@@GEO2004 I want to show you to image but I cannot send my image to you by a comment in TH-cam. Could you send me your email?
You can upload the images yo googledrive or dropbox, and refer the link to this comment box
@@GEO2004 this is my link of my problem. mega.nz/file/UOIijZxK#QShGhVZsGk_DDuNY-j58DFiIQ-KVFtIpFM_HAhxMpLg
Your result cant be avoided and that is the common result if you are using sentinel-1 data for your dem interferometry, here are why:
1. Sentinel-1 is a C band SAR. Radar at C band, X band, even L band cant penetrate the landcover, so significant temporal differences will resulting in failure interferogram generation (due to low coherence), that is because the landcover of the master and the slave images has been changed.
Then may be you asking why my result is quite good?, .my result is good because I am using imagery that covers desert/arid region which mostly didnt have vegetation cover, so the landcover condition is not changed between the dates, I can get a good coherence and upmy interferogram can be formed
2. The only way to get a good DEM from C-band or X-band SAR sensor is the master and slaves imagery temporal differences should be as short as possible (even few hours differences cant be accepted, it should be in seconds or minutes), that is also explain why SRTM which is also using C-band bring two SAR antennas, it is designed to make the temporal differences is super short, and Sentinel-1 isnt.
what is the resolution of the DEM
Vary between 10 to 15 meters
@@GEO2004 what is the maximum definition achievable in a DEM?
About the resolution? 10 meters is maximum
@@GEO2004 how is it possible to obtain measurements to the millimeter to monitor, for example, bridges?
see the research "Displacement monitoring and modeling of a high-speed railway bridge using C-band Sentinel-1 data"
It is possible because theoretically radar backscatter phase is so precise and accurate (gps technology is also using wave phase measurement to determine location),
The problem is, SAR phase measurement is heavily depended on many factors. For example, SAR based displacement measurement is considered as LoS (line of sight) displacement. Different incidence angle of SAR measurement will resulting different displacement result. There are also components in SAR displacement measurement, vertical and horizontal component. They are adding the complexity. This is why single interferometric displacement measurement wont gave accurate displacement rate.
To overcome this, SAR based displacement measurement employ Persistent scatterer interferometry technique. It is a technique to monitoring the height difference of certain object (such as bridge) over a very long time. So it is will cancel out or generalize the variance between measurement, and average displacement rate measurement result can be obtained with a higher degree of confidence.
Hello, i appreciate your video i learn much,but my question is ¿how i do to choose a couple imagens whit the same base line?.
You can use ASF baseline tool,
a short tutorial about tips and tricks to properly select SAR imagery pair for interferometric processing : th-cam.com/video/2TxAXYSDyYQ/w-d-xo.html&lc=UgylMg3yKZEyAut9uWN4AaABAg
halo, izin bertanya ketika saya di tahap snaphu unwrapping kenapa setelah 9% ilang begitu saja ya? tidak ada notif tidak ada apa-apa. Filenya ada namun tidak dapat dimasukan ke app SNAP, mohon pencerahannya jika ada
Sepertinya karena memory ram ga kuat. Bisa diinfokan ram nya berapa?
@@GEO2004 RAM nya 8 gb kok, apa masih kurang untuk app SNAP ini?
Oke, berikutnya, anda memproses satu subswath atau hanya beberapa bursts?
@@GEO2004 satu subswath
Coba dulu dua atau tiga burst dalam satu subswath, kalau sukses, berarti ram 8gb anda tidak cukup buat ngolah satu subswath,