create contours from scanned map and export it to dxf file

2608
2
10-09-2012 07:36 AM
JanCibera
New Contributor
Hi everyone, I hope you can help me. I have an old map, which I scanned. In this scan (Tiff) I need to vectorize contours with appropriates elevations. Later I want do a TIN from it. Can you advise me the best way to do it please? I tryed tool Contour,but it needs define of interval and raster for automatic recognizing. But I want to do it manually.Thanks so much for help...
Tags (2)
0 Kudos
2 Replies
JimW1
by
Occasional Contributor II
I'd use ArcScan and convert the raster to vectors. On old maps this is a long and tedious process (that I do not miss doing). There are a few other non-ESRI products that aren't bad but ArcScan is really the fastest. You'd still need to assign an elevation to each contour manually.

I'd also suggest taking the TIF into photoshop and first converting it into a black and white image (not greyscale but actual binary black and white) and then manually erase everything that isn't a contour - title blocks, rivers, buildings, etc.. The more noise you erase, the less time you'll spend on vector conversion. I'd also run it through a 'sharpen edges' filter to try to thicken the lines up. Then run the new tif through arcscan and create vectors. Then you'll have to manually assign the elevation values to each vector or just ignore that part if you don't actually need elevations.

Then you can make your dxf.
0 Kudos
MarkBoucher
Regular Contributor II
Sounds like it may be easier to have a student worker manually digitize the contours...
0 Kudos