Global Mapper v25.0

Export to KMZ discoloration issues

britterj
britterj Global Mapper User
edited May 2013 in Technical Support
Hello,
I am currently experiencing some issues when exporting a geotiff (24-bit) to a KMZ (tiff - palette). We currently have several geotiffs (exported from ArcGIS 10.1) for each area of interest that are loaded into global mapper. We are attempting to use global mapper to break these large geotiffs into smaller tiff files that could then be loaded onto a GPS. However, we are experiencing an issue in which some of the smaller tiffs that are generated have slight discoloration. I have attached a picture as an example. This image showed two square tiffs that were generated.The tiff that is on the left of the image is the correct coloring (light tan) and that is how most of the land cover is on the ArcGIS exports. However, as can be seen in the right of the image, this tiff instead changes the coloring of the land cover to white. The next tiff over to the right of this colored tiff (not pictured) is again the light tan color. When zooming out, a type of checker-board of these lighter tiff image "squares" are seen. We are unsure what is causing them. We have ran the export multiple times and the same tiff images are always lighter, so the problem is consistent. As mentioned, on the larger tiffs exported from ArcGIS, we have made sure that these areas are the lighter tan and not white and have concluded that they are, so the problem seems to occur when exporting through global mapper. We have made sure that no stretching is occurring in the global mapper software (version 14.2) but we still have these same issues. I am sure it is just a setting or something, but we have tried all of the settings that we could think of with no luck. If anyone else has experienced this issue, a solution would be greatly appreciated. Thanks.

Ben

Comments

  • britterj
    britterj Global Mapper User
    edited May 2013
    To further specify. When we convert the GeoTiff (24-bit) to KMZ (tiff-24 bit), it does not appear to cause a discoloration issue. However, our client wants the output in 8-bit tiff due to limited size on the GPS unit. (A side note: If the geotiff was exported from ArcGIS as an 8-bit geotiff, then when exporting to KMZ (tiff-palette), that works fine without discoloration also. However, the quality of the 8-bit geotiff is too bad to use. Therefore, we really need to find a way to export the higher quality geotiff into the smaller 8-bit tiff KMZ format.
  • global_mapper
    global_mapper Administrator
    edited May 2013
    I think the issue is that when you export to an 8-bit TIFF in the KMZ each individual tile will separately have an optimum palette determined based on the contents of that tile and there could be some discrepancies between adjacent tiles. If you set your background color to the land cover color under the View menu that should force that exact color to be in the palette and then you should get an exact match.

    If you want to match every color I would do a single palette GeoTIFF export for the whole thing from Global Mapper, then load that back in and export that to a KMZ. Since the original already has a palette each tile should end up using that same palette rather than trying to calculate an optimum one.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • britterj
    britterj Global Mapper User
    edited May 2013
    The second option worked like a charm. Thank you very much for your help!