Thanks to Pteryx for this great data set! In order to generate a geo-referenced NDVI / EVI / EVI2 Vegetation Index we need to fly the area of interest (AOI) with a visible (RGB) and full spectrum (RGB+NIR) camera. Once the RGB and RGB+NIR images are processed inside DroneMapper we have two orthomosaic results from which we can generate a pure NIR ortho. To do this, we use GDAL and the following command:
/usr/local/bin/gdal_calc.py -A VIS.tif -B NIRVIS.tif --outfile=nir.tif --calc="(A - B)"
Now that we have created our pure NIR orthomosaic we can use this to generate NDVI or other calculations using OTB in an automated fashion.
/usr/local/bin/otbcli_BandMath -il NIR.tif VIS.tif -out ndvi.tif -exp "ndvi(im2b1, im1b1)"
In order to process the orthomosaic tif files, they need to be the exact same size and pixel resolution. OTB also has many other useful commands for remote sensing work. The original flight and area of interest is 1.0 km sq @ 10 cm GSD.
Thanks -- JP @ DroneMapper