Create new points from selected line (contour) feature does not inherit elevation

JakeJake Global Mapper UserPosts: 264Trusted User
edited November 2013 in Bug Report
GM v14.2 (b071113) 64 bit
Windows 7 64 bit

Contours when converted to points via the "Create new points from selected area and lines features" do not inherit the elevation of the contour.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2013
    When I create points from a contour line (a generated on in this case) I get both an ELEVATION attribute on the point and it also gets the name from the contour line. Are you not getting any attributes or anything?

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • JakeJake Global Mapper User Posts: 264Trusted User
    edited November 2013
    The contours are from this dataset.

    http://ftp2.cits.rncan.gc.ca/pub/canvec/50k_shp/340/e/canvec_340e06_shp.zip

    Specifically layer 340e06_7_0_FO_1030009_1.

    Selecting (FEATURE INFO) a contour identifies it as Unknown Line Type with a non-zero value for attribute ELEVATION. So good so far.

    Clicking on Vertices in the FEATURE INFO dialog lists all vertices as Elevation = 0. Which is still OK since the line retains the elevation.

    So when I do the step as explained in Post 1 (line to points) the points lose the elevation attribute. All the other attributes are inherited. See attached Feature INFOs.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2013
    The problem is the per-vertex elevations of the line. Basically the lines are 3D lines with every vertex set to 0, then they also have an ELEVATION attribute. The per-vertex elevations are used for each point to create an ELEVATION attribute which overrides the existing single ELEVATION value since per-vertex elevations contain more information than a single attribute. In this case though the per-vertex elevations are wrong, they should either not be there at all or should all match the value of the ELEVATION attribute.

    To fix this, first select all of the lines with the Digitizer tool, then right-click and under the Vertex Editing submenu select the option to remove per-vertex elevations from the selected lines. Then create the points and there won't be any incorrect per-vertex elevations to mess things up.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • JakeJake Global Mapper User Posts: 264Trusted User
    edited November 2013
    Thanks Mike. For the per-vertex elevations explanation and the solution.
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