gdal - Mapbox Studio for macOS renders GeoTiff into webp with black background - suggestions?

We are converting a 11 MB GeoTiff, 324511630_Descanso_FSTopo.tif, to post to Mapbox, using Mapbox Studio Classic macOS.

The issue is when the Mapbox tileset is posted in Mapbox.com/studio, there is a black border that extends beyond the original GeoTiffs bounding box.

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Why does a black border appear, and why does it extend past the bbox?

The GeoTiff is on the right hand side of this image. The gray back ground is the Mapbox style light.

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Steps to reproduce

• wget http://data.fs.usda.gov/geodata/rastergateway/data/32116/fstopo/324511630_Descanso_FSTopo.tif


• Mapbox Studio Classic for macOS, New Source > Blank Source > New Layer > Select 324511630_Descanso_FSTopo.tif


• Upload to Mapbox Settings > Upload


• Alternativly, set the zoom to 11-12 for a faster testing process


• The upload is successful with this metadata as reported by Mapbox.com/studio

Format | Type   | Size     | Zoom Extent | Bounds
webp   | raster | 19.28 MB | z11-16      | -180.0,-85.1,180.0,85.1

Notes and Observations

• The GeoTiff is georeferenced and is 7.5 minutes, so the bounding box does not match the GeoTiff bounding box


• The resulting Mapbox tile is webp, which is what we want as we like the size and performance vs png.

What we've tried

• As a comparison, We have modified gdal2tiles.py to use the WEBP tile driver, and it also has the same black border affect.


• When rendering with gdal2tiles.py with PNG tile driver, there is no issue with the black ground, but the file size in Mapbox.com/studio is > 50 MB.


• from gdalinfo we see this data ColorInterp=Palette & Color Table (RGB with 256 entries) 0: 55,53,53,255


• We are aware of the gdal tools, but we don't know how to set the NODATA given the gdalinfo.


• gdal_translate -a_nodata 0,0,0,255 in.tif out.tif # QGIS only accepts one parameters, so this must be wrong

and we tried this, but produces the same issue

• gdal_translate -of vrt -expand rgba 324511630_Descanso_FSTopo.tif rgba.vrt


• gdal2tilesp.py -z 11 -f WEBP --srcnodata 0,0,0,255 rgba.vrt


• mb-util rgba rgba.mbtiles


• Upload rgba.maptiles


• We also tried -expand rgb instead of rgba. No difference

gdalinfo 324511630_Descanso_FSTopo.tif

Driver: GTiff/GeoTIFF
Files: 324511630_Descanso_FSTopo.tif

       324511630_Descanso_FSTopo.tif.aux.xml
Size is 9598, 11366
Coordinate System is:
GEOGCS["NAD83",
    DATUM["North_American_Datum_1983",
        SPHEROID["GRS 1980",6378137,298.2572221010002,
            AUTHORITY["EPSG","7019"]],
        AUTHORITY["EPSG","6269"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],

    AUTHORITY["EPSG","4269"]]
Origin = (-116.625000000000000,32.875000000000000)
Pixel Size = (0.000013023968607,-0.000010998187728)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  COMPRESSION=PACKBITS
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-116.6250000,  32.8750000) (116d37'30.00"W, 32d52'30.00"N)

Lower Left  (-116.6250000,  32.7499946) (116d37'30.00"W, 32d44'59.98"N)
Upper Right (-116.4999959,  32.8750000) (116d29'59.99"W, 32d52'30.00"N)
Lower Right (-116.4999959,  32.7499946) (116d29'59.99"W, 32d44'59.98"N)
Center      (-116.5624980,  32.8124973) (116d33'44.99"W, 32d48'44.99"N)
Band 1 Block=9598x1 Type=Byte, ColorInterp=Palette
  Min=0.000 Max=14.000 
  Minimum=0.000, Maximum=14.000, Mean=10.365, StdDev=3.715
  Metadata:
    STATISTICS_MAXIMUM=14
    STATISTICS_MEAN=10.365010457425

    STATISTICS_MINIMUM=0
    STATISTICS_STDDEV=3.7148361607928
  Color Table (RGB with 256 entries)
    0: 55,53,53,255

    1: 238,51,56,255
    2: 253,179,56,255
    3: 187,139,90,255
    4: 132,119,116,255
    5: 207,182,159,255

    6: 187,195,168,255
    7: 253,202,182,255
    8: 234,214,190,255
    9: 200,230,209,255
   10: 253,222,210,255
   11: 220,221,223,255
   12: 0,176,239,255
   13: 201,217,240,255
   14: 255,255,255,255
   15: 0,0,0,255

   16: 0,0,0,255
   17: 0,0,0,255
     entries 18 through 254 are identical
   255: 0,0,0,255