[EMAIL PROTECTED] wrote:
<< I have JPEG images of 1:50,000 topographic maps. From these, I need to
extract feature objects (roads, rivers, buildings, etc.). I can mask out
colors and save different copies (e.g., save a copy with only green to
represent trees), but how do I proceed to convert these green areas into
vector objects? I've looked through the MI/MB documentation, but couldn't
find anything. The area I've got is about 40km x 50km so, naturally I'm not
looking forward to manually coding the points! Any help or suggestions? >>
I my view you describe two different types of "raster-to-vector" conversions:
one for lineal features (roads, rivers, political boundaries, etc.) and
another for areas (forested areas, lakes, etc.). And I believe different
tools are needed for these two types of problems.
For conversion of lineal features any standard raster-to-vector tool used in
drawing applications will do the trick. However, in converting areal features
you will want to make sure that adjacent areas in the raster image don't
result in vector-based regions with a lot of slivers and overlaps along
common boundaries. For this you want something specially designed for
extracting regions from the raster image, such as the MapTools region
extraction tool. Information about this tool can be found at the URL:
http://members.aol.com/MapTools/
Robert Edwards
The MapTools Company
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