Global Mapper Pro

Exporting A GeoTIFF with the backgound as transparent

CJolly
CJolly Global Mapper User
edited August 2013 in Raster Data
I am trying to export a raster image but want the background to be transparent as it is an odd shape and not square. It presently takes my background color set in GM. I have tried cropping to the shapefile, which does crop the image, but still puts the background as "white". Is there a way to change this so it is only the image coming out as I am loading this into another package that I cannot change the background color to transparent. Is there maybe another format to use?

Comments

  • global_mapper
    global_mapper Administrator
    edited January 2013
    Are you checking the option to 'Mark Background/Void Pixels Transparent' when doing the export? That should add an alpha channel to the image which marks which pixels are transparent. Not all software recognizes alpha channels from GeoTIFF files though.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
  • suvas
    suvas Global Mapper User
    edited August 2013
    I'm in GM 14 now. When I follow the above process the image looks distorted. There is always differences in patterns of distortions between every test image I clip. I'm trying to bring in an aerial image which is mosiac of two different images with a black uneven band in between.

    Thank you.
  • global_mapper
    global_mapper Administrator
    edited August 2013
    Do the images overlap? It sounds like they aren't color balanced together so even when you strip off the collar you get an obvious edge. If they overlap what you can do is draw a coverage polygon for the actual data on the top image, then select that area and go to the Feathering tab of the Options dialog for the image and choose to feather to the selected area. Then you can specify the blend distance and get a smooth transition between then rather than a stark border.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • suvas
    suvas Global Mapper User
    edited August 2013
    Yes the images do overlap. Each image as a black uneven thick black null boarder(NAIP images). When overlapped with another one, one side still shows the black null space regardless of which one is on top. Is this the collar you are talking about? How do I strip off the collar? How do I make this seamless square overlapped image clip so I can bring it in AutoCAD?

    suvas.

    Do the images overlap? It sounds like they aren't color balanced together so even when you strip off the collar you get an obvious edge. If they overlap what you can do is draw a coverage polygon for the actual data on the top image, then select that area and go to the Feathering tab of the Options dialog for the image and choose to feather to the selected area. Then you can specify the blend distance and get a smooth transition between then rather than a stark border.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • suvas
    suvas Global Mapper User
    edited August 2013
    The images do overlapp. I'm trying to clip a box image which unfortunately needs two rasters together. There appears a thick black null boundary which you migth be referreing to the collar. How do I get rid of this to get a seamless image?

    Thank you
    suvas.
  • global_mapper
    global_mapper Administrator
    edited August 2013
    There is a technique at GPS Satellite Map - GPS World Map - Mapping GPS for removing overlapping black (or white collars).

    If you need to export and have them removed in another application though and not just at the seams of the images then you need to have an area/polygon feature describing the boundary. If the data came with say a Shapefile of the boundary you can use that, or you can draw one. Select the boundary once you have it, then go to the Cropping tab of the Options dialog for the layer and specify to crop to the selected polygon.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
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