Project Terra MODIS L1B Swath to L3 500m Sin Grid

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grossg99
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Project Terra MODIS L1B Swath to L3 500m Sin Grid

by grossg99 » Tue Jun 28, 2022 12:05 pm America/New_York

Hi, I am currently trying to use the two MODIS products L1B MOD02HKM and L3 MCD12Q1 to determine the TOA reflectance of each IGBP land cover type. The problem I am running into is how to project the swath format for L1B to the 500m sin grid of the L3 product. Since the swath projection tool is no longer supported, I am not sure how to go about this. Thanks

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LAADS_UserServices_M
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Re: Project Terra MODIS L1B Swath to L3 500m Sin Grid

by LAADS_UserServices_M » Wed Jun 29, 2022 7:21 am America/New_York

There are couple of ways you can reproject MODIS L1B swath products. You can utilize LAADS DAAC's post-processing option available from LAADS search and order interface. You can learn more about this option by reviewing tutorials provided at:
https://ladsweb.modaps.eosdis.nasa.gov/learn/how-to-search-and-order-data-with-the-laads-find-data-interface/

Another option is to use Land Data Operational Product Evaluation (LDOPE) Reprojection Tool available at:
https://ladsweb.modaps.eosdis.nasa.gov/tools-and-services/#ldope
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grossg99
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Joined: Tue Jun 28, 2022 12:01 pm America/New_York

Re: Project Terra MODIS L1B Swath to L3 500m Sin Grid

by grossg99 » Wed Jun 29, 2022 1:09 pm America/New_York

Oh thank you so much! In the post processing option, I chose sinusoidal with bilinear resampling for the L1B data. The resulting images, however, do not appear to line up with the MODIS sinusoid tiles easily, is there a way to do that? Attached is swath and sinusoid grid I'm looking to overlay, with the highlighted swath being the greyscale image, which was sinusoidally reprojected. Thanks
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OB SeaDAS - knowles
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Re: Project Terra MODIS L1B Swath to L3 500m Sin Grid

by OB SeaDAS - knowles » Wed Jun 29, 2022 2:34 pm America/New_York

You can use the SeaDAS software to reproject NASA OBPG MODIS L1B files to the projection of a mapped image file. Use the SeaDAS Reproject Tool with the MODIS L1B file as the input (source) file and choose "Use CRS of" to specify the mapped file which contains your desired (coordinate reference system) projection. The SeaDAS Reproject Tool should work with your files as well.

grossg99
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Joined: Tue Jun 28, 2022 12:01 pm America/New_York

Re: Project Terra MODIS L1B Swath to L3 500m Sin Grid

by grossg99 » Tue Jul 05, 2022 12:40 pm America/New_York

Thank you so much! The tool is exactly what I need. I guess the only other question I have is and I can't seem to find it, does it automatically scale to TOA reflectance with the MOD02HKM product? It seems like it does, but I'm not 100% sure, or if I needed to scale it to radiance, I'm not sure where to do that either. So my question is, does the L1B reader scale the output so what you see is in reflectance, and can you cite your source so I can make note of it?

Thanks again

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