Trying to create an intersection of two (or more) viewsheds

Steve DSteve D Global Mapper UserPosts: 21Trusted User
edited June 2010 in Vector Data
Per the title, I want to figure out the commond ground covered by multiple tower sites. I can cheat and do this in a photo editor quite easily, but would like to work with it in GM as well.

To quote the manual:
Finding the Intersection of Multiple Area Features

You can find the intersection of two area features by selecting both features, then right clicking and selecting the Find Intersection of Selected Area Features menu command. This operation will create a new area feature from the intersection of the two selected area features. You will also be prompted to create new area features from what is left outside of the intersection. If you choose this option then the original area features will be marked as deleted once the operation completes successfully.

I'm not seeing the "Find Intersection of Selected Area Features" menu command. I'm pretty new at using this software and any help would be appreciated.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2010
    What version of Global Mapper are you using? The option to find the intersection of selected features in only in the v11.xx release series of Global Mapper.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Steve DSteve D Global Mapper User Posts: 21Trusted User
    edited June 2010
    I'm running 11.02.
  • Frank2Frank2 Super Moderator Posts: 105
    edited June 2010
    Use the Digitizer Tool, then select your areas and proceed from there.
  • Steve DSteve D Global Mapper User Posts: 21Trusted User
    edited June 2010
    Hrmm. I thought it should be as easy as that. I've attached a screenshot of the menu I get when I right click. In the picture I have two viewsheds and both are selected.
    Edit: Attachments are shrunk to point of being unreadable. Gimme a moment, I'll put it on imageshack or something

    Edit 2: Try this: nointersection.png

    Uploaded with ImageShack.us
  • Frank2Frank2 Super Moderator Posts: 105
    edited June 2010
    I believe it's because you have 311 features selected, rather than just two areas as the help says ("You can find the intersection of two area features"). I'll let Mike take it from here.
  • Steve DSteve D Global Mapper User Posts: 21Trusted User
    edited June 2010
    Okay, I think I'm figuring this out. Each viewshed is in a seperate overlay, and the intersection works on features within a single overlay. (I figured this out finally after drawing a couple polygons with the digitizer - it puts them into one overlay.)

    I just need to figure out how to combine each viewshed into a single overlay now.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2010
    As Frank said, the area intersection function only works to find the intersection of 2 selected area features. It doesn't matter what layers the area features are in, only that you have exactly 2 areas selected. It wouldn't really make sense to find the intersection of all 311 areas that you have selected as there wouldn't be any areas common to all 311 areas, so the intersection would be empty.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Steve DSteve D Global Mapper User Posts: 21Trusted User
    edited June 2010
    Yes, I see that now. I guess I'm looking for a way to intersect two entire layers with each other, rather than just individual features. It really doesn't matter that 250 of the 300+ features become blank, that's kind of the point of what I'm trying to do. That's fine if that's a limitation of the software, I have other means to my ends. Right now, I can do it easily as a final step in a external photo editor (such as Paint.net), it just doesn't allow me to continue working with it since it's rasterized at that point.

    Thanks for the help though!
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2010
    There is not currently any way in Global Mapper to find the intersection of two different layers of area features, although that is something to add to the todo list.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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