Extending .asc surface on a horizonatl plan

rbrearrbrear Global Mapper UserPosts: 3
edited June 2013 in Elevation Data
Hi,

I'm not sure if this is possible but I have a .asc surface (Water Level) which sits above and is smaller than another .asc surface (Ground). Currently the water surface boundary does not intersect with the ground as it's extents are not great enough. I would like to extend the surface out until it intersects with the ground surface. Then create a line feature for length of intersection.

Thanks for any help provided.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited May 2013
    Assuming the water level is flat at a single elevation, you could skip the water level surface altogether and just use the Analysis menu command to create contours and create just a single contour value at the water level. Also check to create contour areas and you should get an area and line for the single water level value.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • rbrearrbrear Global Mapper User Posts: 3
    edited May 2013
    Thanks for prompt reply. One of my surfaces is flat so this will work great however another is water that is running down a slope in a gully and therefore isn't flat. The issue is the flood planning level is 0.5m above the water level and needs to be outlined on the map.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited May 2013
    You might be able to use the new water level rise calculator under the Analysis menu. With that you can select your flood plain area (create a coverage polygon for the surface if that's what you have), then use the water rise option and choose to calculate the area some height (like 0.5m) above the original flood plain polygon. Then you can see where it would be with that level of water rise.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • rbrearrbrear Global Mapper User Posts: 3
    edited June 2013
    I now have 14.2 and the water rise tool. I'm having a few issues attempting to use it. They are

    1) It raises an area feature and I have a .asc file. I can make an area feature by right clicking and use the create feature along boundary however I am then unable to give the area feature elevations. I tried using the get elevations from surface but it would not work, I believe this is because the area feature created is bounding (just outside) the surface. So how do I create my 3d Area feature for the water rise which has levels sourced directly from the existing water .asc.

    2) The water rise tool does not seem to create a surface. Can this be done.

    Thanks,

    Ron
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2013
    Ron,

    If you select your area feature with the Feature Info Tool you can press the Vertices button and add per-vertex elevations. Are the per-vertex elevations all the same for the area or should they vary? If you need to get them from the surface you could create a buffer area from the area with a small negative distance to shrink it. You will then have an area feature inside the original that you should be able to get elevations from the terrain surface with.

    The water rise doesn't currently create a surface but instead just a new area. You could assign elevations to the new area from the terrain and then create an elevation grid from the new water rise area and the original area being raised if you want though. It should smoothly transition from the original one to the raised one.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    Global Mapper
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