I have been trying to export a number of scanned paper maps onto my database, and have been just adding them as raster layers as part of a larger group layer. I georeferenced them, and none of them overlap (they are smaller towns around the county). When I create a mosaic dataset and add the rasters to it, the file ends up being around 40 GB. This is odd, because I also used the same process with about 500 maps of the same file size (which slightly overlapped and filled an entire area) and the final mosaic dataset only took up about 5 GB.

Is there a way to make the file size smaller or store the rasters more efficiently?

  • 3
    So the the scanned maps are not adjacent but there are large empty areas in the mosaic? Empty pixels take space in the image file as well. Compression with "deflate" or "LZW" methods should compress empty areas pretty well. – user30184 Jun 14 '16 at 10:44
  • So I just created a new mosaic dataset. When I added all of the maps to it that don't overlap, I went to "environments" and then to "raster storage", and changed the compression type to "LZW" (I didn't see "deflate"). When the rasters added, the uncompressed size of the mosaic was 330 or so GB. Is this what you were saying to do or did I get something wrong? I'm sort of new to ArcGIS. Thanks! – Alex D. Jun 14 '16 at 20:21
  • If using LZW compression requires 330 GB while having no compression at all takes 40 GB then there must happen something that I do not understand. I am not really ArcGIS specialist either. – user30184 Jun 14 '16 at 21:30
  • I think I may have been confused; I linked the rasters together with the "append" tool to create the 40 GB file. I have tried to mosaic them with multiple types of compression methods and they were all the same size (330 GB). I also tried the "Mosaic to New Raster" tool and the output was around 60 GB. – Alex D. Jun 15 '16 at 14:12
  • Would you be able to edit your question to revise it with the current state of your and @user30184's efforts to try and resolve it, please? The question in your title does not seem to be a summary of its contents. – PolyGeo Jun 24 '16 at 23:50