Global Mapper Pro

Crop Raster to another Raster's extent

durga637
durga637 Global Mapper UserTrusted User
edited July 2012 in Raster Data
Hi,

I am using 13.2 version and tried to Crop Raster to another Raster's extent.
In detail, I have a country specific raster/DEM and loaded to global mapper. Then I used download online imagery option to get landsat7 world imagery. Now I have my country specific dem under and upon I have landsat imagery.
I want to crop landsat imagery to my country raster/dem extent only. I mean as it is like a country shape (irregular). so that i can have on one layer I can see dem and another landsat image. How can I achieve this??? I tried the raster options but I found a reference should be vector/area file.

How to Crop Raster to another Raster's extent??

Thanks,
Prasad.

Comments

  • global_mapper
    global_mapper Administrator
    edited June 2012
    Prasad,

    You would first need an area feature describing where you want to crop. If you have a DEM that covers that, you can right-click on that layer in the Control Center, then select the option to create equal value areas, then specify a very large elevation value so that you end up with just a single coverage polygon for wherever the DEM is valid. Once that is created, simply select that and crop the Landsat layer to that, either through the Cropping tab of the Raster Options dialog or by exporting and using the option to crop to the selected area on the Export Bounds tab of the export dialog.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • durga637
    durga637 Global Mapper User Trusted User
    edited July 2012
    Hi Mike,

    I followed as you said and succeed in cropping. Now I tried exporting landsat cropped file and getting message as "no compatible and exportable data available" Pls advise.
    Thanks,
    Prasad.
  • global_mapper
    global_mapper Administrator
    edited July 2012
    Prasad,

    What format are you trying to export the Landsat data to?

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • durga637
    durga637 Global Mapper User Trusted User
    edited July 2012
    Mike,
    I tried to export in Geotif format.
    Any suggestion/advise on export format?

    Thanks,
    Prasad
  • global_mapper
    global_mapper Administrator
    edited July 2012
    Prasad,

    The GeoTIFF format is good, just make sure you are selecting one of the image options for the format, like 8-bit palette or 24-bit RGB, as you can't export imagery (like Landsat) to an elevation flavor of GeoTIFF, otherwise you would get an error like you are seeing.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • durga637
    durga637 Global Mapper User Trusted User
    edited July 2012
    Hi Mike, I am trying to export in Geotif format from two days...it shows that it is processing even after 10 hours...ans shows that it will take another 10 hours to complete....it is processed only 4% so far.... I really dont know if it really takes that much time...Pls check the attachment. Pls advise. Thanks, Prasad.
    bhu.jpg 99.7K
  • global_mapper
    global_mapper Administrator
    edited July 2012
    Prasad,

    How large of an area are you exporting and at what resolution? It looks like you are exporting from the online Landsat source and that can be VERY slow for large areas, especially at high resolution. I would try exporting at a lower resolution if using an online source.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • durga637
    durga637 Global Mapper User Trusted User
    edited July 2012
    Hi Mike, I am trying your suggestion to import lansdat7 data of Bhutan area and experiencing these problems. Pls check the attachment. Thanks, Prasad.
  • global_mapper
    global_mapper Administrator
    edited July 2012
    Prasad,

    That is a pretty large area, but the crop polygon might also be the issue as it can be quite slow to crop to a complex area. If you don't need the boundary to be extremely precise, I would first suggest simplifying the crop area with the Digitizer Tool (right-click and select to simplify it), then crop to the simplified boundary. Also what resolution are you exporting at? I wouldn't go over 15m resolution since that's all the Landsat data is. You might also try using the Gridding tab to split your export into multiple smaller pieces which will speed up the cropping time as well. You can then combine those.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
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