topic Re: raster to polygon, adjusting for line thickness in raster? in Data Management Questions

raster to polygon, adjusting for line thickness in raster?

jasonross2 — Wed, 04 Dec 2013 04:33:36 GMT

I have a scanned cadastral map and need to turn it into polygons. I've registered the raster and whatnot, and now raster-to-polygon seems to be the ticket, but when i run it I get polygons defined by each side of the raster line, as the raster line is somewhat thick. I would rather it place the polygon co-incident border down the center of the raster line, but am not sure how to accomplish this.

ie. my polygons are separated by about a 2m space, as that is the thickness of the raster line in pixels.

I tried first going raster to polyline, but that seemed to take forever, and either complained that the output would be larger than 2gig, or just hung, which I don't understand as the polygon process took seconds, and the raster is certainly not that big, nor are the amount of line features (equivalent of maybe 2 city blocks).

Any advice on how to account for this line thickness is appreciated, I'm also open to other/better approaches to doing this task.

Thanks.

Re: raster to polygon, adjusting for line thickness in raster?

JimCousins — Thu, 05 Dec 2013 12:49:15 GMT

You should run the thin tool first.
Spatial analyst tools >> Generalization >> thin
This will limit the number of pixels used to represent a vector object, and thereby produce better output on the raster to vector conversion.
Best Regards,
Jim

Re: raster to polygon, adjusting for line thickness in raster?

jasonross2 — Fri, 06 Dec 2013 18:39:37 GMT

Thanks for the reply, I tried the thinning but didn't get exactly what i was after.

However, I then discovered the ArcScan toolbar, and that does the trick perfectly.

Thanks again.