[mapserver-users] How reproduce a false color NDVI.

[aperi2007]

Hi Even,

I'll try to test the usage of the VRT format (I never use it before).

Thx,
Andrea.

Il 01/03/2015 10:35, Even Rouault ha scritto:
> Le dimanche 01 mars 2015 10:17:34, Andrea Peri a écrit :
>> Hi,
>> we have a set of tiffs georef with 4th bands of color RGB and Infrared.
>> We need to activate a wms with the color from the NDVI index
>>
>> NDVI = Normalized Difference Vegetation Index
>>
>>            NIR - RED
>> NDVI = -------------
>>            NIR + RED
>>
>>
>> Where NIR is the 4th band,
>> RED s the 1th band.
>>
>> We prefer dont' do a physical float raster, but retrieve this realtime from
>> the original tiffs.
>>
>> I try to reproduce this index NDVI using to a LUT table in MapServer,
>> but without any success.
>> There is some other solution to obtain this on mapserver.
> Andrea,
>
> It turns out that the same question was asked more than 10 years ago :
> http://lists.osgeo.org/pipermail/mapserver-users/2004-July/053754.html
>
> Since them, GDAL has the VRT format. With derived bands (described near the
> end of http://gdal.org/gdal_vrttut.html), you could do that but that requires
> writing a custom function in C, which isn't very convenient for integration
> with MapServer. It would be nice to add the capability of writing pixel
> functions in Python.
>
> Even
>