Global Mapper v25.0

Create polygons based on elevation value?

Hello, I'm wondering if you guys can help me brainstorm here. I'm trying to create polygons around areas of either a grid or lidar points corresponding to specific elevation values. I don't have the lidar package so I'm a little limited in what I can do with lidar files. 

For example: Say I had a bunch of elevation grid or lidar files and I wanted to create a polygon around areas that had negative elevations.

I've been working my way through the user/reference guides for GM and I haven't been able to find a way to accomplish this. 

Any ideas?

Thanks!

Answers

  • bmg_bob
    bmg_bob Global Mapper Programmer
    Hello,

    You can to this using the Generate Contours functionality.  If you put a check next to "Generate Area Features Colored Based on the Current Elevation Shader in Addition to Contours", you will get area features.  If you you only want negative elevations, set the Elevation Range accordingly.

    Cheers,
    Bob
  • eddie416
    edited November 2016
    This creates a bounding shape around the entire dataset as well as the negative areas. I've played with the options a great deal and can't get it to generate without that bounding shape. The bounding shape is not something I want in my result. Any ideas on that? Are there options I'm missing?
  • bmg_bob
    bmg_bob Global Mapper Programmer
    eddie416 said:
    This creates a bounding shape around the entire dataset as well as the negative areas. I've played with the options a great deal and can't get it to generate without that bounding shape. The bounding shape is not something I want in my result. Any ideas on that? Are there options I'm missing?
    Please post a screen capture of the options you used, and the result with the bounding shape you are trying to get rid of.  Thanks.

    Cheers,
    Bob
  • Here are the settings used, and the result. The negative areas can be seen inside the big, bounding red area. The other image is what the data looks like. I've tried playing around with the settings but haven't been able to create a result that didn't contain the bounding area.