[Gdal-dev] Sinusoidal projection for MODIS images with OGR

[Ben Discoe]

Answering my own question here.. the values given by MODIS for lat/lon are
the center of the _image_, not necessarily the center of the projection.
When i tell OGR Sinusoidal, with dfCenterLong=128, the other params 0, then
the image appears more or less where i expect it.  It's still offset a bit,
but it's certainly in the right overall projection.  The offset is probably
due to ellipsoid differences, or some such.

-Ben

> -----Original Message-----
> Subject: [Gdal-dev] Sinusoidal projection for MODIS images with OGR
> 
> This evening i tried to load some images from the MODIS Gallery
> (http://rapidfire.sci.gsfc.nasa.gov/)  They are .jpg, with 
> .jpw world files.
> The projection is described in a separate .txt file, like this:
> 
>  projection: Sinusoidal
>  image center lon: +128
>  image center lat: +38
>  ellipsoid: Sphere
>  Earth radius (km): 6371.007181
> 
> When i looked at OGR for a way to describe this projection, i found:
> 
>   OGRSpatialReference::SetSinusoidal(dfCenterLong, dfFalseEasting,
> dfFalseNorthing);
> 
> This doesn't seem to take a "center lat" parameter, so i'm 
> left wondering how to tell it about the MODIS image?
> 
> Thanks,
> Ben