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I have created pyramid layers for my ASTER satellite images (.img) using Gdal Tools "Build Overviews" (Pyramids). The dialog said "Processing completed". I don't have the impression that zooming in or out has been accelerated in any way and under "Properties" / Pyramids there is still the "description", no pyramids are listed.

Does anybody know how I can find out about this?

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You can check the existence of pyramids with gisinternals GDAL standalone version by typing the command gdalinfo filename in the SDK shell.

There the pyramids are called Overviews.

You can also find the overviews in the metadata tab of the layer properties in the dimensions chapter. If you have overviews, you find more than one entry there.

It might be necessary to delete and re-add the raster file layer to your QGIS project to see those changes.

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  • I have deleted and re-added the file.So when under "Dimensions" there is a list: X: 2771, Y 2441 / X: 1385, Y 1220 [...] X: 43, Y 38 does that mean there are pyramid layers? Jun 19, 2013 at 14:54
  • yes ;-) For me, the list starts with 56832 and ends up with 1776. This speeds up rendering enormously. Your files are rather small. I guess you have lots of them, if QGIS reacts slowly. Would be a good case for using a virtual index on them.
    – AndreJ
    Jun 19, 2013 at 15:08
  • Thanks a lot! Maybe it's not due to the files that it is so slow right now since I only have 4 images, too... Jun 19, 2013 at 15:22
  • If anybody from the future sees this: When you have built the pyramids, instead of removing the layer and adding it back in, you can try pressing F5 when the layer is visible and see if that helps already. It did in my case, but I realize this is 2020 talking to 2013. The entry under "Dimensions" didn't change for me, but I guess it will when I open up the project next time.
    – thymaro
    Oct 19, 2020 at 9:47

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