Global Mapper Pro

Combine Terrain - Operation Help

DustyRobinson
DustyRobinson Global Mapper UserTrusted User
edited December 2011 in Elevation Data
I have two terrain layers loaded of a coastal area. The first one is very detailed, but only includes above water elevations. The second one is not as detailed, but includes below water elevations. What I would like to do is keep all of the first (detailed) elevations except where the first is below 0.1 (water areas). In those areas I would like to use the second (less detailed) elevations, but only if they are below 0. I can't clip the second to areas below 0 because it is a tidal marsh, and it gets really messy with all the variation, so I need some sort of automated method.

I am wondering if there is a multiple step process that would accomplish this?

I think I need some sort of custom if-and statement like; keep second if first is less than (0.1) and second is less than (0).

Comments

  • global_mapper
    global_mapper Administrator
    edited December 2011
    What you can is clamp your "above water" data set to have a minimum valid elevation of 0.1, then just load it on top of the other one. The other data set should then only show through then where the "above water" data set is below 0.1

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • DustyRobinson
    DustyRobinson Global Mapper User Trusted User
    edited December 2011
    How do I do that?
  • DustyRobinson
    DustyRobinson Global Mapper User Trusted User
    edited December 2011
    I got the "above water data" to only show values above water. This is very close to what I need. I am still in need of one more filter or something. It is difficult to explain, so I included an imageFilter problem.jpg
  • global_mapper
    global_mapper Administrator
    edited December 2011
    You would do the clamping on the Alter Elevations tab of the Options dialog. Can you clamp the "above water" one to 0.1 on the low side and the "below water" one to 0 on the high side, then also check the box to replace invalid with "0" for the "below water" one that is underneath the "above water" one? Then you should get what you want I think.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • DustyRobinson
    DustyRobinson Global Mapper User Trusted User
    edited December 2011
    That did. I have never played around with those options before. Very helpful tools that I will be using a lot.
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