Topo - Contour Lines- DEM

[christopherbeattie]

Hi,

I am trying to create a DEM from a 1894 topo map. I have been researching the most effective way to do this but I am still struggling to find the best way. Do I digitize the contour lines by hand and use the Topo to Raster tool? Any thoughts? It would be greatly appreciated. Thanks!

Chris

[TimBarnes]

Depending on the quality/clarity of the map, georeferencing it and then digitising the contours for use in a TIN or Raster is a valid approach.

Alternatively, look at something like ArcScan (http://resources.arcgis.com/en/help/main/10.1/index.html#//000w00000001000000) which can automatically extract features from an image/scan. Obviously, on a very 'busy' map or a low quality scan, a human eye and brain may be better at extracting the lines from the image than an algorithm. If the area is fairly small also, it may be easier and cost effective to just digitise it by hand 🙂

Remember also, that the shape of the land may not have changed significantly (or at all) since 1894 so sourcing 'modern' DEM data for that area may be a better approach.