Hello Martin,
Sorry couldn't reply earlier as I was stuck with some college work.
On Mon, 2 Apr 2012 21:00:51 +0200, Martin Landa wrote:
Hi,
2012/4/2 Mohit Kumar <mohit.kumaru...@students.iiit.ac.in>:
I am interested in making a PostGIS manager in GRASS as a GSoc
2012 task.
PyGreSQL is a python module that allows easy use of database
operation
API
from a pyhton script. So it will be like a wrapper over
the database. This can be done using wxPython and will be OS
independent.
Sorry to bug you all, but I am very much interested in developing
for
GRASS.
[...]
there is new development ongoing for this in GRASS 7, perhaps a
good
moment to integrate a manager. Maybe Martin has some insights for
us over the next days.
Its good to know that development is ongoing for this in GRASS, I
sincerely
want to work on this as my GSoc task.
the current PostGIS-related development in G7 is not much related to
this idea. The vector engine in G7 is currently able to read PostGIS
geometry data natively without any abstract level (like
OGR-PostgreSQL
driver). Also write support has been recently implemented. The
current
implementation is focused on simple feature access, GRASS builds a
pseudo-like topology as for OGR links (see v.external). At this
moment
I am working on PostGIS topology support in GRASS.
I have made a brief idea for the manager. The following are the
various
modules of the manager
1. Setup connection : This module will set up the connection with
the remote
database. It will take the input parameters from user and pass them
to a
connection string. After the connection has been established, the
user will
be shown the various tables(maps) that are stored and other
information
about the database and the connection
This is already available in wxGUI [1]. Of course there is always a
space for any kind of improvements. But basically it's already there,
to add widgets for entering username and password is quite easy task.
2. View and edit data : This will display the data of the table in a
window
frame. One can view the map and modify the table values or the
attributes.
Also possible in current wxGUI [2]. You just create a link using
`v.external` and display the map in the map canvas as normal GRASS
vector map. Also direct OGR access [3] is possible (no links,
pseudo-topology built on the fly)
3. Import to GRASS Data : This gives the user an option to save the
data in
Grass format for further processing/analysis of the data. This also
gives
user an option to discard the data which is of no use.
Possible with `v.in.ogr`. Simple wrapper based `v.in.ogr` for
importing PostGIS is already there [4].
4. Execute PostGis functions (geometry processing)on database and
save
output in grass data format.
This could be improvement.
5. SQL interface : This provides the advanced user to modify the
database by
use of direct SQL commands on the database.
6. Export GRASS data to PostGIS data : Convert the Grass Data to SQL
database. First convert the Grass data to Esri Shapefile(.shp) using
OGR and
then converting that data to SQL database (shape2sql).
Why?? You can export data directly using `v.out.ogr` [5]. No need for
Shapefiles, that's bad idea.
7. Projection support : I was also thinking of adding projection
support to
the manager.
In which sense, do you mean on-the fly re-projection (ST_transform)?
Martin
[1]
http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Using_wxGUI
[2]
http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Digitize_OGR_layer_using_wxGUI
[3]
http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Direct_access_to_external_data
[4] http://grass.osgeo.org/wiki/PostGIS#Import_into_GRASS
[5] http://grass.osgeo.org/wiki/PostGIS#Export_to_PostGIS
Thanks for your feedback.
I know that various modules are possible in GRASS wxGUI. I want to
integrate them all and provide a direct interface for them. Regarding
data Export I was thinking about 'v.out.ogr' only.
And I was talking about on-the fly re-projection. The projection tables
can be stored in which ever way the user wants.
What more would you like to add to the current idea to make it worth
for a GSOC proposal?
Looking forward to your support.
Regards,
Mohit Kumar (mohitkharb on irc)
Lab For Spatial Informatics
International Institute of Information and Technology
Hyderabad, India
+91-970-3840-175
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