[GRASS-dev] r.grow.distance and latlong?

GRASS GIS GRASS GIS developer
1

Hi,

to my understanding the r.grow.distance code lacks support for
LatLong locations. AFAIK G_begin_distance_calculations() and
G_distance() would be needed here.

Any opinions?

Markus

2

On Sat, Sep 1, 2012 at 2:07 PM, Markus Neteler <neteler@osgeo.org> wrote:

Hi,

to my understanding the r.grow.distance code lacks support for
LatLong locations. AFAIK G_begin_distance_calculations() and
G_distance() would be needed here.

The -m flag to use geodesic distance for latlong locations has been
present in r.grow.distance (trunk) for quite some time (4 years).

Markus M

3

On Sun, Sep 2, 2012 at 2:15 PM, Markus Metz
<markus.metz.giswork@gmail.com> wrote:

On Sat, Sep 1, 2012 at 2:07 PM, Markus Neteler <neteler@osgeo.org> wrote:

Hi,

to my understanding the r.grow.distance code lacks support for
LatLong locations. AFAIK G_begin_distance_calculations() and
G_distance() would be needed here.

The -m flag to use geodesic distance for latlong locations has been
present in r.grow.distance (trunk) for quite some time (4 years).

I have now locally backported it.
However, the result with and without -m in a latlong location is identical,
hence -m seems to be broken.

Markus

4

On Sun, Sep 2, 2012 at 2:38 PM, Markus Neteler <neteler@osgeo.org> wrote:

On Sun, Sep 2, 2012 at 2:15 PM, Markus Metz
<markus.metz.giswork@gmail.com> wrote:

On Sat, Sep 1, 2012 at 2:07 PM, Markus Neteler <neteler@osgeo.org> wrote:

Hi,

to my understanding the r.grow.distance code lacks support for
LatLong locations. AFAIK G_begin_distance_calculations() and
G_distance() would be needed here.

The -m flag to use geodesic distance for latlong locations has been
present in r.grow.distance (trunk) for quite some time (4 years).

I have now locally backported it.
However, the result with and without -m in a latlong location is identical,
hence -m seems to be broken.

Ah, one need to use metric=geodesic.
So, in LatLong it works with metric=geodesic but not with -m.

MarkusN

5

On Sun, Sep 2, 2012 at 2:38 PM, Markus Neteler <neteler@osgeo.org> wrote:

On Sun, Sep 2, 2012 at 2:15 PM, Markus Metz
<markus.metz.giswork@gmail.com> wrote:

On Sat, Sep 1, 2012 at 2:07 PM, Markus Neteler <neteler@osgeo.org> wrote:

Hi,

to my understanding the r.grow.distance code lacks support for
LatLong locations. AFAIK G_begin_distance_calculations() and
G_distance() would be needed here.

The -m flag to use geodesic distance for latlong locations has been
present in r.grow.distance (trunk) for quite some time (4 years).

I have now locally backported it.

Backported to 6.4 and 6.5.

MarkusN