[gdal-dev] gdalwarp problems with MODIS L1B

[Rutger]

Hey,

Maybe i'm missing something, but for as far as i know, the MODIS MOD021KM
product is still a 'swath', and therefore still containing the bow-tie
effect as the result of the scanning sensor. Wouldn't this mean that
gdalwarp will never work? The lat/lon arrays aren't continuous, so any
fitting (GCP/TPS) wont be accurate. And upsampling the arrays with cubic,
like Even did, will result in interpolating pixels which are next each other
in the array/file, but aren't next to each other 'on the ground', wont work
well.

I think you need to either use a dedicated algorithm (like gradient search),
or something very generic (like the KDTree of Pyresample) to overcome the
bow-tie effect.

I have spend alot of time experimenting with this in GDAL, since i try to do
as much with GDAL as possible. But projecting a swath file from a scanning
sensor (like MODIS or VIIRS) is something i have never gotten to work. For
some historic discussion about this see for example:
http://osgeo-org.1560.x6.nabble.com/gdal-dev-reproject-python-numpy-binary-swath-lat-lon-td4978609.html


Regards,
Rutger



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