[gdal-dev] Merging Multi-Band Drone Imagery

[Javier Jimenez Shaw]

Hi Nathan

Unfortunately there is not ColorInterp for NIR or RedEdge. But you can use
the "Description" of the bands. QGIS will use that name. I do not know how
to do it in gdal_merge (I did in C++).

About computing the NDVI, as far as I know there is no trick to do it in
the "Layer Styling". If anybody knows how to do it, please tell us! So the
solution is to use a raster calculator, and do the maths there.

Representing the "true" colors in QGIS of such images is not easy. Are they
radiometrically corrected? QGIS will try to adjust the min and max value of
each band, that are usually very different. You should adjust it properly.

Cheers

On Fri, 19 Apr 2024 at 23:52, Raley, Nathan via gdal-dev <
gdal-dev at lists.osgeo.org> wrote:

> I have individual TIFS from the different sensors on the drone.
> Currently, I have the R, G, NIR, and Redge bands.  Is the correct method to
> merge these into a multi-band image that I can then view as NDVI or apply
> other algorithms against just to use:
>
> gdal_merge.py -separate R.TIF G.TIF NIR.TIF RE.TIF -o multispec.tif
>
> I noticed that only the first band is listing as:
> Band 1 Block=2580x1 Type=UInt16, ColorInterp=Gray
> whereas all the others are listing:
> Band 2 Block=2580x1 Type=UInt16, ColorInterp=Undefined
>
> Any attempts to define them as ColorInterp=Gray through gdal_edit fails to
> yield any results.
>
> I was just wanting to confirm I have the correct workflow here.  I haven’t
> had any luck viewing the multispec.tif within QGIS by applying any
> RasterCalculations on the bands in the multispec.tif, so I was wanting to
> confirm I’m not doing anything incorrectly.
>
> I’ve also attempted to pull out the blue band from the RGB camera, and add
> that to the multispec.tif as well, after scaling it from the 0-255 to the
> 0-65535, and that displays the blue band in there.  I can then ColorInterp
> bands 1, 2, and 3 as red, green, and blue, then it appears to let me
> specify the 4 and 5 bands as gray, but the colors are way off.
>
> Can anyone offer some assistance?
>
>
>
> Thanks,
>
> Nathan
>
>
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