[GRASSLIST:4592] Re: vector road map from tiff image

[Glynn Clements]

Philip Mark Donaghy wrote:

> Can grass read a tiff image

Yes, with r.in.tiff.

> and detect lines and polygons to create a 
> vector basemap of lines and polygons?

Yes, with r.poly (polygons) and r.line (lines).

> To complicate things the image has 
> text and icon labels. The number of unique colors in the image is 1687. 
> It seems obvious to me that I will have to modify/simplify the image to 
> get good results. But I don't know to what degree.

You will probably need to remove the labels prior to analysis. If the
number of colours reflects the fact that areas or lines use a range of
colours, you would need to fix that also.

> Can anyone with some ideas tell me which grass module does this type of 
> raster to vector transform? I can provide a sample image if necessary.

r.in.tiff, r.poly, r.line, and r.thin and v.support are likely to be
relevant. Some of the other modules might be useful for pre-processing
the data.

-- 
Glynn Clements <glynn.clements at virgin.net>