[GRASS-dev] v.generalize and LatLong?

GRASS GRASS developer
1

Hi,

I wonder if v.generalize should work in LatLong? I tried to use the
displacement but the result is identical. Maybe a map unit (threshold
given in meters but currently considered in map units = degree?).

Any hint welcome,
Markus

2

Markus Neteler wrote:

Hi,

I wonder if v.generalize should work in LatLong? I tried to use the
displacement but the result is identical. Maybe a map unit (threshold
given in meters but currently considered in map units = degree?).

I guess v.generalize uses map units, i.e. degrees for latlong, but
guessing without checking every single smoothing and simplification
method. At least I can't remember having seen anything when I last
went over the code of v.generalize. Functionality handling latlong
should be implemented in the vector libs (there is already
Vect_line_geodesic_length() but that is not enough).

Markus M

3

Markus N wrote:

I wonder if v.generalize should work in LatLong? I tried to use the
displacement but the result is identical. Maybe a map unit (threshold
given in meters but currently considered in map units = degree?).

did you run v.build.polylines first?

Hamish

4

On Thu, Feb 17, 2011 at 11:58 PM, Hamish <hamish_b@yahoo.com> wrote:

Markus N wrote:

I wonder if v.generalize should work in LatLong? I tried to use the
displacement but the result is identical. Maybe a map unit (threshold
given in meters but currently considered in map units = degree?).

did you run v.build.polylines first?

I tried, it does not make a difference. So LatLong will be the problem.

Markus