Create new points from selected line (contour) feature does not inherit elevation
Jake
Global Mapper UserTrusted User
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.
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
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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 -
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. -
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 -
Thanks Mike. For the per-vertex elevations explanation and the solution.
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