I've an old countour map (hard copy drawn ages ago) which now I want to digitize.
I've scanned this map (can be saved in JPEG, PDF etc format) however I don't know if there is an easy way to create contour lines from this JPEG image.
really appreciate inputs in this regard.
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The easiest way is to vectorize 'em automatically by means of the free Wintopo, then in Autocad you assign elevation to the resulting contours.
Quite frankly, if you are not planning on doing this very often, just scale it (properly) and trace with polylines. You will be waaay ahead.
Saw your quotes on the *EE* video by Brian Kling. Way to go! Excellent and congrats <G>
Raster Design has a contour follower in the vectorization tools. It will create polylines with elevations as a best fit to the raster pixels. It's not perfect but probably better than manual tracing. See the Raster Design help file for the contour follower tool.
I'd agree that tracing is a good option for the occasional project of this nature. As mentioned Raster Design and other programs will do this type of work. However they usually need human intervention unless you have a very clear image. So between the cost and the fact that it would probably not be a automatic as you hope. Tracing on screen is a good way to go.
If you do trace on screen. You can save some time by setting the Elevation variable to the contour elevation before you start to draw each polyline. Remember to use 2D polylines as elevation.
If you have a clean image there are some PDF to DWG converters with free trials like THIS ONE. you still have to set the elevation.
You can clean things up preyy easily in raster before convert.
Thak you all for your replies.
Yes, this is one off project where I need to do this and requirement for accuracy probably dictates the method to be adopted...so I guess doing it manually is the best fit.
Kinga, please pay attention to the mentioned freeware Wintopo, 'cause it's well-suited for "line art" like raster contours.
Finally it may convert the result not only to vector DXF but also to shapefile, to which you can add geometric fields as area or length with opensource software, e.g. Qgis.
I've used Wintopo and it does a reasonable job although I imagine the quality of the output will depend on the quality of the jpeg used
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