Overlaying an MBTilesImage on other map gives black region

[OlaRune]

I'm trying to overlay an MBTilesImage on another map, for example using this earth file:

<map>
    <GDALImage name="World">
        <url>../data/world.tif</url>
    </GDALImage>
    <MBTilesImage name="One tile">
	<url>../data/onetile.mbtiles</url>
    </MBTilesImage>
</map>

I have uploaded my data here (available for seven days, tell me if I should reupload it): https://www.transfernow.net/dl/202304119RfrPaXq

The data contains one .tif file and one .mbtiles file that I have created using this line:

osgearth_conv --in driver GDALImage --in url 64_4_00.tif --out driver MBTilesImage --out filename map.mbtiles --out format jpg

When doing this, the MBTilesImage has black borders around it that cover the background map. It differs depending on zoom level, see the attached screenshots.

How do I remove the black region or make it transparent? I would prefer if this can be done without modifying the .mbtiles file, because I have a much larger file that took ages to process, but if I have to reprocess it I can do that.

[gwaldron]

Your mbtiles file appear to be in jpeg format, which does not support transparency. You might try regenerating your mbtiles in png format.

Another option would be to add a shader to your layer that will look for black pixels and discard them.

[OlaRune]

Oh, it was that simple. Thanks!

[plevy]

I usually look at this example:
https://github.com/gwaldron/osgearth/blob/master/tests/wms_nexrad.earth