[GRASS-dev] r.buffer distance overshoot in GRASS 7.0 with geographic coordinates

GRASS GIS GRASS GIS developer
1

Hi developers,

I have just taken a script that uses r.buffer in GRASS 6.4 and moved
it to GRASS 7.0. I am using geographic coordinates, and in GRASS 6.4,
r.buffer (as advertised) worked just fine in meters by doing the
appropriate transformation. However, in GRASS 7.0, the buffer is ~20
times too wide (a quick guess), which doesn't indicate conversion
to... well, anything I can think of. The units seem to be working fine
(km are way bigger than meters), so I'm guessing that something got
misplaced somewhere in the source and is rescaling everything. Does
anyone have an idea of what is going on / how to fix it?

This was brought up in the start of another thread:
http://osgeo-org.1560.n6.nabble.com/Using-r-buffer-on-image-with-geographic-coordinates-td3887623.html
but not mentioned again.

Thanks!

Andy Wickert

2

On Mon, Feb 13, 2012 at 10:27 AM, Andy Wickert <wickert@colorado.edu> wrote:

Hi developers,

I have just taken a script that uses r.buffer in GRASS 6.4 and moved
it to GRASS 7.0. I am using geographic coordinates, and in GRASS 6.4,
r.buffer (as advertised) worked just fine in meters by doing the
appropriate transformation. However, in GRASS 7.0, the buffer is ~20
times too wide (a quick guess), which doesn't indicate conversion
to... well, anything I can think of. The units seem to be working fine
(km are way bigger than meters), so I'm guessing that something got
misplaced somewhere in the source and is rescaling everything. Does
anyone have an idea of what is going on / how to fix it?

Fixed in r50792.

Markus M

3

Thanks a ton, Markus! Just recompiled and it works perfectly.
Andy

On Mon, Feb 13, 2012 at 7:44 AM, Markus Metz
<markus.metz.giswork@googlemail.com> wrote:

On Mon, Feb 13, 2012 at 10:27 AM, Andy Wickert <wickert@colorado.edu> wrote:

Hi developers,

I have just taken a script that uses r.buffer in GRASS 6.4 and moved
it to GRASS 7.0. I am using geographic coordinates, and in GRASS 6.4,
r.buffer (as advertised) worked just fine in meters by doing the
appropriate transformation. However, in GRASS 7.0, the buffer is ~20
times too wide (a quick guess), which doesn't indicate conversion
to... well, anything I can think of. The units seem to be working fine
(km are way bigger than meters), so I'm guessing that something got
misplaced somewhere in the source and is rescaling everything. Does
anyone have an idea of what is going on / how to fix it?

Fixed in r50792.

Markus M
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