Remove overviews from image

Problem:

When loading an orthophoto image into LP360/Topolyst no image is displayed, yet when you zoom in it becomes visible. Modifying the LP360 image display properties shows the image extents properly and the header checks out.

Probable resolution:

We suspect that the overviews in the image file are corrupt/invalid. One can use the GDAL tool to remove overviews and then tell LP360/Topolyst to rebuild them.

1. Download the software called OSGeo4W from http://trac.osgeo.org/osgeo4w/
   1. Select either the 32-bit or 64-bit depending on your OS and follow installation instructions.
2. Run OSGeo4W command shell
3. Run the command, “gdaladdo -clean <filename>” in the OSGeo4W command chell.
   1. You will need to include the full path to the ortho, such as “gdaladdo -clean “C:\MappingProject\othro.tiff””
   2. You may need to quote the full path and file name if there are spaces. The easiest thing to do is drag your file into the shell window.
4. When successful this command will remove the overlay from the image and it should now load into LP360/Topolyst and be visible. You can verify there are no overviews by reviewing the header information once you’ve added the raster the Add Files dialogue.