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Extracting Contours from Topo Map

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#1
BahaZ

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I was just curious on the steps involved in extracting contours from a topo map (without digitizing them), delineating the contours from all the other vector features after raster to vector conversion, and then the creation of a DEM. Is the delineation of the contours possible in ArcGIS (with toolbox functions) or do you need image software like ERDAS or ENVI (with RGB classification)? From my knowledge, I believe only the latter will do?

Edited by BahaZ, 09 June 2009 - 01:36 PM.


#2
frax

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I am not sure what you are asking here... do you mean scanning a printed topographic map, and extracting the contours from that... ?

I am not sure I get the "without digitizing" part - at some point you have to digitize, right? (as in convert a printed matter to digital)

Or do you mean, without digitizing, as in old school digitzing (puck on a big board)
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#3
Matthew Hampton

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I think the workflow BahaZ is considering is turning a paper topo map into vector contours. Years ago I toyed with the idea and came across ESRI's ArcScan for ArcGIS. If you want an ArcGIS solution I think this is where you need to start.

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#4
BahaZ

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I think the workflow BahaZ is considering is turning a paper topo map into vector contours. Years ago I toyed with the idea and came across ESRI's ArcScan for ArcGIS. If you want an ArcGIS solution I think this is where you need to start.



Yes exactly Matt. Thanks for the link I wasn't aware of that extension. Anyone real familiar with it and does it work well in delineating contours from other vector phenomena? Also what other software is better for such a process?


And frax, yeah I meant scanning the map into a topo image, but not using the digitizing puck and board (never ever tried that) or manual computer digitizing tools to follow the contour lines, but rather extract them with some semi-automatic process.


And what about going to a DEM once the contours are extracted? What is the best method/tool? Topo to Raster?

#5
CGIS

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We've used Golden Software's Didger with great sucess - it's a really powerful program, and for the price, it can't be beat.




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