[GRASS-user] link to datasets from other locations?

GRASS GRASS user
1

Tim Michelsen wrote:

There exist v.external and r.external to link to data which
hasn't been imported into GRASS.

But in order to save time and disk space I would like to
link to data sets from other locations:

How do I link to a raster and vector data in another
location presuming it has the same projection?

add the mapset as a symlink to the mapset in the other location,
then use the @othermapset notation.

(at your own risk)

Hamish

2

A related issue – I’d like to use r.external but I can’t seem to get it to work. I’m running wxPython for GRASS 6.4 (from the Osgeo4W installation). r.external seems to work properly, but when I try to display the result, I get an error message telling me that GDALAllRegister can’t be found. Here, I’ve reproduced this in the spearfish60 dataset:

r.out.gdal input=elevation.10m output=elev_dem10.img format=HFA type=Float32
r.external input=elev_dem10.img output=elev_dem10_rext
d.rast map=elev_dem10_rext

The layer shows up in the layer manager as “raster (double-click to set properties)”. I double-click and the name changes to elev_dem10_rext@user1…

Then I try to Zoom to Layer, or click on the Display Map button and I get:

Execution fiailed: ‘d.rast.exe map=elev_dem10_rext@user1 --q’
Details:
Error: Unable to locate symbol

(By the way, I’ve also encountered this error message trying to do r.mapcalc on a GRASS file imported using r.in.gdal.)

Has anyone encountered this error? Is there a way to fix it?

Thanks,
Matt

Hamish wrote:

··· 
-- 
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Matthew Landis, Ph.D.
Research Analyst
ISciences, LLC
61 Main St.
Burlington VT 05405
802.864.2999
--------------------------------------------------
3

hamish-2 wrote:

How do I link to a raster and vector data in another
location presuming it has the same projection?

add the mapset as a symlink to the mapset in the other location,
then use the @othermapset notation.

So sharing data between locations is not really supported?
Even if I just want to add the layer to the map view?

Regards,
Timmie

--
View this message in context: http://n2.nabble.com/link-to-datasets-from-other-locations--tp3185792p3188925.html
Sent from the Grass - Users mailing list archive at Nabble.com.

4

Timmie wrote:

>> How do I link to a raster and vector data in another
>> location presuming it has the same projection?

> add the mapset as a symlink to the mapset in the other location,
> then use the @othermapset notation.

So sharing data between locations is not really supported?
Even if I just want to add the layer to the map view?

The only operations which access data in a different location are
those where the data is necessarily in a different location because it
uses a different projection, e.g. re-projection or rectification.

In general, if it's possible for the data to be in the current
location, then it must be.

--
Glynn Clements <glynn@gclements.plus.com>

5

add the mapset as a symlink to the mapset in the other location,
then use the @othermapset notation.

As GRASS is aim to support Windows, this is not an option

6

add the mapset as a symlink to the mapset in the other location,
then use the @othermapset notation.

As GRASS is aim to support Windows, this is not an option

7

On Wed, Jul 1, 2009 at 2:03 PM, Matthew Landis<landis@isciences.com> wrote:

A related issue -- I'd like to use r.external but I can't seem to get it to
work. I'm running wxPython for GRASS 6.4 (from the Osgeo4W installation).
r.external seems to work properly, but when I try to display the result, I
get an error message telling me that GDALAllRegister can't be found. Here,
I've reproduced this in the spearfish60 dataset:

I contacted FrankW about this, here his answer:

On Mon, Jul 6, 2009 at 3:17 AM, Frank Warmerdam<warmerdam@pobox.com> wrote:
...

I have upgraded my OSGeo4W GRASS 6.4.0svn install to the latest available
from OSGeo4W and then tried running r.external and it appears to work fine.
I have also run depends.exe on r.external.exe and it properly depends on
gdal15.dll so there is no reason it wouldn't normally pick up the copy in
C:/OSGeo4W/bin.

If someone had another copy of gdal15.dll in c:/windows/system32 it might
get used instead of the proper one and cause problems though I don't know
why it would be missing gdalallregister.

Sorry I was unable to find anything helpful.

Markus