[gdal-dev] Creating Mosaic - Ensuring Maximum Pixel Value is brought forward

[Shaima Alsharif]

Dear Developers,

I am working on generating a mosaic, and I need to ensure that the maximum
pixel value (dBZ) is selected when merging overlapping raster files.
Despite my attempts using gdalbuildvrt and gdalwarp, I continue to
encounter issues where it does not always pick the maximum pixel value in
overlapping areas.

notes: CRS is EPSG:4326 and GDAL 3.8.5, released 2024/04/02

Commands Used:

1.
gdalwarp -overwrite -multi -r
max  /nfs/radar/max-reflectivity/tiff/raw/*/2025/3/5/20250305T2145*.tif
test-20250305T2145.png.composite.tif
or
gdalbuildvrt test-20250305T2145.png.composite.vrt
/nfs/radar/max-reflectivity/tiff/raw/*/2025/3/5/20250305T2145*.tif

gdalwarp -overwrite -q -r max test-20250305T2145.png.composite.vrt
test-20250305T2145.png.composite.tif


2.

gdaldem color-relief -alpha -q test-20250305T2145.composite.tif \
/color-ramps/reflectivity/titan.txt \ test-20250305T2145.png
*Questions:*

   1. How can I ensure that gdalbuildvrt properly stacks overlapping
   rasters while keeping the maximum pixel values?
   2. Is gdalwarp -r max the correct approach to pick the highest dBZ
   reflectivity values?

Any guidance or suggestions would be greatly appreciated! Thank you in
advance for your help.

With Regards,
--
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