Hello! ALL,
I need to learn the important way of working with the data having different projection system for a single location. Usually the case is between long lat and UTM projections. I set the region first with g.region and then try to import vector data which is in long lat format they do not get “on the fly” transformation in the GRASS and what I find that they cannot be displayed in my region.
The second question is that is it possible to create two different mapsets, one in Long lat and other in UTM for the same location and then work upon these two simultaneously even displaying them.
I hope to get some very good guidance on these issues.
thanks!
Ambrish Dhaka
Are you an untamed, bizarre or daring explorer? Find out now! Drag n’ drop
ambrish dhaka wrote:
Hello! ALL,
I need to learn the important way of working with the data having different projection system for a single location. Usually the case is between long lat and UTM projections. I set the region first with g.region and then try to import vector data which is in long lat format they do not get “on the fly” transformation in the GRASS and what I find that they cannot be displayed in my region.
GRASS does not do “on the fly projection”. There are some good explanations on the list why “on the fly” isn’t such a good idea. {1}
The second question is that is it possible to create two different mapsets, one in Long lat and other in UTM for the same location and then work upon these two simultaneously even displaying them.
No, you don’t work that way. You need two separate LOCATIONs, one for UTM and a second for LAT/LON. Then use r.proj or v.proj to pull maps from one to the other. MAPSETs are for sets of maps which are logically related: same work project or in the same place, etc. But everything in one MAPSET must be in the same projection and LOCATION.
Hi Ambrish,
I'd suggest you use Q-GIS for the display of the maps with different projections. It happily reads GRASS rasters and vectors. It also has a neat plugin to convert from on projection to another.
Note however that Q-GIS is not a replacement for GRASS in terms geo-processing.
Cheers
Micha Silver wrote:
ambrish dhaka wrote:
Hello! ALL,
I need to learn the important way of working with the data having different projection system for a single location. Usually the case is between long lat and UTM projections. I set the region first with g.region and then try to import vector data which is in long lat format they do not get "on the fly" transformation in the GRASS and what I find that they cannot be displayed in my region.
GRASS does not do "on the fly projection". There are some good explanations on the list why "on the fly" isn't such a good idea. {1}
The second question is that is it possible to create two different mapsets, one in Long lat and other in UTM for the same location and then work upon these two simultaneously even displaying them.
No, you don't work that way. You need two separate LOCATIONs, one for UTM and a second for LAT/LON. Then use r.proj or v.proj to pull maps from one to the other. MAPSETs are for sets of maps which are logically related: same work project or in the same place, etc. But everything in one MAPSET must be in the same projection and LOCATION.
--
Micha
[1] http://n2.nabble.com/link-to-datasets-from-other-locations-td3185792.html#a3193823
I hope to get some very good guidance on these issues.
thanks!
Ambrish Dhaka
------------------------------------------------------------------------
Are you an untamed, bizarre or daring explorer? Find out now! Drag n' drop <http://www.ExploreMyWay.com>
This mail was received via Mail-SeCure System.
------------------------------------------------------------------------
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
This mail was received via Mail-SeCure System.
------------------------------------------------------------------------
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
Ravinder Singh Bhalla wrote:
Hi Ambrish,
I'd suggest you use Q-GIS for the display of the maps with different projections. It happily reads GRASS rasters and vectors. It also has a neat plugin to convert from on projection to another.
But you need to be aware that QGIS does NOT re-project raster layers on the fly. Only vectors in different projections will overlay properly.
--
Micha