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I have downloaded the STRM files (.bil) for Hawaii and rendered them in QGIS. They render as grayscale heightmaps. Although all of the tiles appear to line up, none appear to be using the same scale. I looked in the other bundled files for scaling information but found none. What am I doing wrong?

enter image description here

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  • @user2856 Thanks, that makes sense. Can you share a link to some of those other questions? I couldnt find much under "SRTM".
    – user8908459
    Commented Sep 11, 2019 at 5:57
  • Can't find one either. It's not specific to SRTM though.
    – user2856
    Commented Sep 11, 2019 at 7:35
  • I didn't use it but this plugins may be usefull : github.com/amondot/contrast-homogenizer
    – J.R
    Commented Sep 11, 2019 at 8:39
  • Main thing you have two problems, first, as mentioned above you have different tiles. Second no data values are not recognized on them. What you can try is to identify the null values (select layer, properties, information). If all your tiles have the same null value you can either to build a virtual raster catalog (raster , Miscellaneous, build virtual raster) and make sure to define your no data values in the dialog box.
    – Gerardo Jimenez
    Commented Sep 11, 2019 at 12:50
  • If your tiles do not have the same no data value, you have to identify the individual no data value for each tile, then using raser conversion translate, convert each tile to a new file, but assigning a common no data values for all tiles. Once you have them in the same format, with the same no data values, you can either buil a virtual raster catalog, as mentioned before or merge all the tiles in one (raster/miscellaneous/merge), and make sure to define your no data values in the dialog box.
    – Gerardo Jimenez
    Commented Sep 11, 2019 at 12:54

1 Answer 1

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There's no scaling in the data. The values are elevation in metres.

Your issue is that each tile has different statistics (min, max, mean, etc.) and QGIS is using those stats to rescale/stretch each tile differently for display.

One fix is to create a virtual mosaic, a "VRT" with gdal or QGIS.

Another is to set the display stretch the same for all tiles in the layer properties - symbology tab for each raster.

Here is the data rendered correctly enter image description here

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