Converting DTMs

Comparing vectors, grids, and TINs

open topo_intro/contours_TIN QGIS project.

    • From DEM to a vector (contour) image (Example here from Lexington).
these examples are from an old Arc project in the same area. Sorry :/

Note how there’s a good bit more information in the 20 ft contours than the DEM.  You can see the river and the steep slopes by the Maury River 

    • From DEM to TIN (you could do that in Arc, haven’t found the magic words in QGIS yet)

    The river doesn’t come out too well because it is narrow.  There is a threshold value that you can set

    You can see how the ridge lines are nicely framed by the TIN however.
    • TINs can also be contoured

The contours on the left are only 40 ft intervals, those on the left are from the above example at 20 ft.