Open zdila opened 3 years ago
May be unrelated, but why do you have both NoData value and alpha?
May be unrelated, but why do you have both NoData value and alpha?
Ok. Developers will give you better answer, but as far as I know alpha for GDAL is often acting like a binary mask "zeros vs anything else than zero". For some other use case I would have a test by changing the interpretation of band 4 into undefined before processing and then back to alpha, but with thousands of tiles that is unpractical.
BTW I can generate png tiles with correct alpha using mapnik-based server (it is just more work to set it up). Also QGIS has no problem interpreting alpha channel correctly.
Please attach a small input file demonstrating the issue
Attached a sample.
Hello everybody, i encounter the same issue. Any news ?
I also experience the same issue. I assume there has been no progress on this?
Expected behavior and actual behavior.
I expect gdal2tiles to copy alpha-channel from the input tif (or vrt) to the output png files. It actually generates pngs where output alpha channel is always 100% for non-nodata pixels and 0% for nodata pixels. I would expect it to have alpha=0% for notada and alpha=value_from_alpha_channel for non-nodata pixels.
Steps to reproduce the problem.
My input file bands:
Command for generating tiles:
Operating system
Linux 5.10.0-6-amd64 #1 SMP Debian 5.10.28-1 (2021-04-09) x86_64 GNU/Linux
GDAL version and provenance
3.2.1