View Full Version : Contour Lines and Elevation Extractor

June 3, 2014, 10:26 AM
Has anyone else noticed that when Elevation Extractor is ran using contour lines, interpolation of elevation is backwards? Is this occuring with anyone else? How can this be fixed?

July 3, 2014, 07:13 AM
Backwards? 100 is 001?

Patrick Moore
June 30, 2015, 02:18 PM

Interpolation of contour lines can be tricky and can periodically result in oddities in the elevation data. This is caused by varied reasons, but most often is associated with errors in the contour data itself especially if there are errors or missing data in the contour line elevation fields. If the contour lines are not continuous lines for each elevation they will have many polylines that have an elevation value associated with them. If small elevation contour lines are missing an elevation value errors can occur when extracting elevations from them.

It is recommended if oddities occur, to run a quick check on the contour elevations by selecting the contours near where node elevation questions exist and verifying all contour lines have elevations assigned.

Ideally, many places nowadays that create contours also publish elevation surfaces. Elevation TIN files or elevation raster files are often much more reliable in extracting elevations and don't have the same potential for oddities as contours sometimes have. If you have access to an elevation surface instead of contours it is usually preferred to do so as they are more reliable.

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