MCD43D60 projection on GDALInfo

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plmarasco
Posts: 2
Joined: Fri May 06, 2022 3:25 am America/New_York

MCD43D60 projection on GDALInfo

by plmarasco » Fri May 06, 2022 9:09 am America/New_York

According to the documentation for these specific products, the coordinate system should be a Geographic lat/lon "projection" referred to as Climate Modeling Grid (CMG).
This statement is confirmed by the fact that, through Panoply, a GCTP_GEO projection is set in the metadata. Sadly GDALInfo is reporting something weird (I'm aware that the best option would be to use the conversion tool from NASA but for specific needs, I've to rely on GDAL )
Here below a metadata extraction of the 'projection' component:

...GEOGCRS["Unknown datum based upon the Clarke 1866 ellipsoid",
DATUM["Not specified (based on Clarke 1866 spheroid)",
ELLIPSOID["Clarke 1866",6378206.4,294.978698213898,
LENGTHUNIT["metre",1],
ID["EPSG",7008]]],...

I've been searching quite a lot but there is no documentation that states Clarke as the valid ellipsoid for this product.
Unfortunately, to complicate the situation, not all the products have the same CRS. The GDALInfo for the MCD43D31.061 doesn't have any metadata for the Coordinate System but through the PARAMETERNAME.1 confirm that has a CMG at 1KM

According to the General Cartographic Transformation Package (GCTP), the projection parameters (available here https://modis-land.gsfc.nasa.gov/GCTP.html) of the 'ellipsoid' should be referred to as a sphere of radius 6371007.181 in case of a projection to a sinusoidal. As the original software is written in the 90es has as default the Clarke ellipsoid, if parameters are not properly set, I'm wondering if an incident occurred at a certain point in the production chain.

Could someone please help me to better understand if the metadata in the MCD43D60 is wrongly assigned? Which would be the best solution? over impose the correct information or data have been compromised in the processing chain and only an intervention during it could solve the issue.

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dnilsen_eros
Posts: 1
Joined: Wed May 18, 2022 12:32 pm America/New_York

Re: MCD43D60 projection on GDALInfo

by dnilsen_eros » Wed May 18, 2022 12:34 pm America/New_York

Could you provide the version of GDAL you are using?

plmarasco
Posts: 2
Joined: Fri May 06, 2022 3:25 am America/New_York

Re: MCD43D60 projection on GDALInfo

by plmarasco » Thu May 19, 2022 5:47 am America/New_York

GDAL 3.4.2
I know that there was something related to it but, to my knowledge, has been already fixed since long time ago.

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