Generating Grids and cropping to corridors

BrandogrammetryBrandogrammetry Global Mapper UserPosts: 10Trusted User
edited February 2012 in Bug Report
When I generate a grid and tell it to 'crop to selected area feature' it only gives me about 5%-85% of the tiles needed to cover the corridor. The only way I've found to get around this is to buffer my corridor by about 4000 feet and then it covers more than I need. Although, it still doesn't cover the entire 4000 ft buffered corridor. I've attached the corridor I'm using this time if anyone wants to give it a try.

Thanks for your help.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2012
    So just to confirm what is happening, you are doing a gridded export and also cropping to a selected area, but not all of the grid cells that intersect the area shape are being exported? What version of Global Mapper are you using?

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • BrandogrammetryBrandogrammetry Global Mapper User Posts: 10Trusted User
    edited January 2012
    Not an export. I'm just creating a grid with the digitizer tool.

    v12.02
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2012
    Ah yes, by default when creating a regular grid of areas the grid cell is only kept if its center is in the crop area. If you want to keep it if any part is in there you can check the option on the Advanced section of the General tab of the Configuration dialog to always keep a pixel on export if any part is in the crop area. A bit non-obvious, but at least there is a way.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • BrandogrammetryBrandogrammetry Global Mapper User Posts: 10Trusted User
    edited January 2012
    Ok, that is what's happening, but that solution didn't work for me. It's only generating tiles that have the center inside of the corridor, like you said, but I'm trying to generate a grid...not export a grid. Can you confirm that the "Export: Keep Pixel if any Part is Inside Crop Area" option applies for grid generation with the digitizer tool too?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2012
    Yes I can confirm that option also applies to grid generation. The name just needs update to reflect its more generic behavior now.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.
  • BrandogrammetryBrandogrammetry Global Mapper User Posts: 10Trusted User
    edited January 2012
    With the option set I don't see any difference. Is it version 13 that this option works for? Thanks for your help.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2012
    Ah yep, that option wasn't used until v13. In v12 it only keeps if the centroid is in the crop area. If you create lines rather than areas then the lines will actually be cropped to the area though.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • BrandogrammetryBrandogrammetry Global Mapper User Posts: 10Trusted User
    edited February 2012
    I got v13 today, but it doesn't look like the problem has been solved. In this version it seems to keep the tile if the centroid or the corner is in the corridor...otherwise it won't create a tile. If you create small tiles then the chance is increased of covering the corridor since at least one corner of the tile will be in the corridor, but if they are larger then they are less likely. You can try it with the shape attached to this thread. If you create 2500' tiles you will notice a couple missing tiles. If you create 5000' tiles or above you will notice most are missing. You can also see that at least one corner or the centroid are inside the corridor for all of the tiles that were created.

    I've checked "Keep Area if Any Part in Crop Area". This setting is what allows the corner to be considered when creating a tile. If that setting isn't checked than it will only create a tile if the centroid is within the corridor. Also, the "Export: Keep Pixel if any Part is Inside Crop Area" option doesn't seem to effect anything in my testing.

    Can you please test and confirm this or am I doing something wrong?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2012
    Sorry the latest change still only worked if either the centroid or one of the 4 corner points was inside the polygon to crop to, which obviously doesn't work when your grid cell size is large compared to the area. I have updated this to do a full crop so it will work regardless. I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip .

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • BrandogrammetryBrandogrammetry Global Mapper User Posts: 10Trusted User
    edited February 2012
    I tested the 64bit version and it works like a charm, thanks a lot!
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