VJ109_NRT is not georeferncing

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amacu
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VJ109_NRT is not georeferncing

by amacu » Fri Nov 17, 2023 6:05 pm America/New_York

Hello!

I'm new to satellite image processing. I am working with a collection of VJ109_NRT - JPPS1 images. It is a L2 VIIRS product. They come with an extension .nc.
I have read the proposed documentation (same for NPP and JPSS-1 products [https://viirsland.gsfc.nasa.gov/PDF/VIIRS_Surf_Refl_UserGuide_v2.0.pdf] and several articles trying to georeference data correctly. The data is supplied with coordinates that are explicitly specified in EPSG:4326 (as example GRingLatitude=-3.70198226, 0.3605142236, -20.11667824, -24.55309677). However, the guide [https://viirsland.gsfc.nasa.gov/PDF/VIIRS_Surf_Refl_UserGuide_v2.0.pdf] mentions that a sinusoidal coordinate system is used for georeferencing. So, I'm using point from boundary box (contained in metadata as GRingLatitude/GRingLongitude). My algorithm is following: I download the images -> get them from geotiff files -> translate the coordinates of the boundaryBox points into a sinusoidal coordinate system -> reproject the image in a sinusoidal system by points -> translate to EPSG:4326? If I use this algorithm, then the position of the objects in the images is very different from the real one. The same happens if I immediately reference to EPSG:4326 using a thin plate spline (TPS).

I use Python GDAL and it is desirable for me to find a solution using this technology. And I also use QGIS to check results (I've implemented above algorithm with QGIS but I've tried in python too and the results are the same).

So I've tried to use some know solutions such as GDAL warp function. But it returns nothing or shifted results. Also I used QGIS to make template. I tried different ways (in different coordinate systems) but objects in images are still not on their places. I've also fixed a bow-tie effect with my python code, but this is not the subject of question.

So, the question is: what is the propper way to georeference JPSS-1 L2 data (VJ109_NRT collection)? If I understood everything correctly, then the method for JPSS-1 should be the same as for other MODIS products (NPP, etc.)

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Re: VJ109_NRT is not georeferncing

by LAADS_UserServices_M » Mon Nov 27, 2023 8:00 am America/New_York

Try using "Reprojection Tool" provided under Land Data Operational Product Evaluation (LDOPE) Tools on LAADS website at:
https://ladsweb.modaps.eosdis.nasa.gov/tools-and-services/#ldope
Here, the user guide provide information on how to install and use these tools.
Regards,
LAADS User Services

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