[gdal-dev] Fwd: Creating MBTiles with transparent background from GeoTIFF

[Rahkonen Jukka]

Hi,

Your original image does not have nodata:
gdalinfo sample_geotiff.tif
...
Band 1 Block=8889x1 Type=Byte, ColorInterp=Red
Band 2 Block=8889x1 Type=Byte, ColorInterp=Green
Band 3 Block=8889x1 Type=Byte, ColorInterp=Blue

MBTiles driver does not support transparency with nodata but with alpha https://gdal.org/drivers/raster/mbtiles.html

One possible workflow:
Convert RGB 0 0 0 pixels into alpha with gdalwarp

gdalwarp -srcnodata 0 -dstalpha sample_geotiff.tif sample_with_alpha.tif

Convert this input with alpha into MBTiles

gdal_translate -tr 0.035 0.035 -of MBTILES sample_with_alpha.tif file1.mbtiles

I guess there are other ways to get a desired result, I stopped experimenting when this seemed to work.

-Jukka Rahkonen-



Lähettäjä: gdal-dev <gdal-dev-bounces at lists.osgeo.org> Puolesta Kanishk Varshney
Lähetetty: maanantai 27. kesäkuuta 2022 15.22
Vastaanottaja: gdal-dev at lists.osgeo.org
Aihe: [gdal-dev] Fwd: Creating MBTiles with transparent background from GeoTIFF


Hey all,

I am stuck with MBTiles creation from GeoTIFF files that have a black background (RGB: 0,0,0).

In QGIS, I am able to generate MBTiles via the following steps:

  *   Set Transparency pixel (0 0 0) to get a geotiff with transparent background
  *   Use Generate XYZ tiles (MBTiles) tool to generate the MBTiles for the above generated geotiff.
I want to automate the workflow using python, but not able to achieve great success.

The following commands are used:

gdal_translate -tr 0.035 0.035 -a_nodata none -of MBTILES file1.tif file1.mbtiles



gdaladdo -r nearest file1.mbtiles 2 4 8 16



This results in following issues:

1. The generated mbtiles don't have all the resolutions that manually generated MBTiles have

2. Background is still black, which is a big concern for my usecase



Any help or alternative would be appreciated. Attaching a sample Geotiff for reference



[https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png] sample_geotiff.tif<https://eur06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1HJaw59FVEwG_9sEN8bvfeRw1GrawGnUb%2Fview%3Fusp%3Ddrive_web&data=05%7C01%7Cjukka.rahkonen%40maanmittauslaitos.fi%7Cf59902129f0d4022d41208da5837ad09%7Cc4f8a63255804a1c92371d5a571b71fa%7C0%7C1%7C637919293399292802%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=hmfLGGUvB05Rl34jbgA%2F6SiI%2BTdImGhVUK%2FEHxGV8d0%3D&reserved=0>





Thanks,

Kanishk
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