[GRASS-dev] d.vect render= and corrupted vector display
glynn at gclements.plus.com
Mon Apr 9 13:46:29 EDT 2007
Maciej Sieczka wrote:
> >> By "boundary case", do you mean to assume that v.in.region+d.vect is
> >> unlikely to be used? Just curios.
> > No, I mean that it's a case where a "point" is neither inside nor
> > outside but on the boundary.
> > The term doesn't refer solely to geometry. In any context where some
> > continuous (non-discrete) space is partitioned into distinct
> > categories, you get values which fall on the boundary between
> > categories. E.g. if you partition the real numbers into positive and
> > negative, which is zero?
> As to display, I guess I get it know. However, I'm not sure what to
> think about this issue in regard to computational GRASS region.
> Let's take a following eaxample; in spearfish:
> $ g.region rast=landuse -a
> $ v.in.region lu_border type=line
> $ v.category lu_border out=lu_border_cat option=add
> $ g.region vect=lu_border_cat
> $ v.to.rast input=lu_border_cat output=lu_border_cat use=cat
> The outcome is a raster which includes only the top and left lines,
> while region was ordered to cover the whole "lu_border_cat" vector.
> From user's point of view, half of the input vector was ignored by
> v.to.rast, in error. Is this not fixable too?
No. Exactly the same issues apply here.
Glynn Clements <glynn at gclements.plus.com>
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