Raster to Vector Conversion

Malcolm Williamson malcolm at cast.uark.edu
Thu Jan 12 16:56:58 EST 1995

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> I've just downloaded the Linux Binaries for GRASS hoping to find a
> utility which can convert a raster image to a dxf file.  I have 20
> source files which are 5100x3300 bitmaps in targa format.  The
> bitmaps are scans of floor plans which I need to convert to dxf for
> import into AutoCAD.  Is this something GRASS can do?  If so, are
> there pitfalls?  Is the output quality high?
> I would endeavor to find this out for myself, but I've got to produce
> drawings for bids in one and a half weeks.  I appreciate any advice
> you can lend on this topic, or pointers to other Raster to Vector
> resources.
> Thanks,
> Scott
> email: srouten at antimony.service.indiana.edu
I'm not familiar with targa format, but I'm fairly confident that GRASS cannot
import it directly. Therefor, you need to convert it to a format that can be
read into GRASS, such as Sun raster format. I'd suggest using the pbmplus
utilities for the raster conversion (tgatopnm | pnmtorast -s ) - these are
available in various locations on the 'Net. After getting this data into GRASS
in raster format, you would use either r.line or r.poly to generate vector data
depending on if the data represents line-type features or polygons (areal
features). Polygon features will result in jagged edges where the vectors follo
the edge of rectangular raster cells - I believe there is a "-s" flag with
r.poly that will smooth this out a little. Given the size of your raster files,
conversion may take a while. Nope, I don't know of any better *free* way!

Malcolm D. Williamson - GIS Specialist           E-mail: malcolm at cast.uark.edu
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-3846
University of Arkansas
Fayetteville, AR 72701

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