[GRASS-user] interactive multiple selection

[Moritz Lennert]

On 22/01/09 07:14, Michael Barton wrote:
> 
> 
> On Jan 21, 2009, at 11:05 PM, <grass-user-request at lists.osgeo.org> wrote:
> 
>> Date: Wed, 21 Jan 2009 18:45:40 +0100
>> From: Vincent Bain <bain at toraval.fr>
>> Subject: Re: [GRASS-user] interactive multiple selection
>> To: GRASS user list <grass-user at lists.osgeo.org>
>> Message-ID: <1232559940.6769.10.camel at vincent-desktop>
>> Content-Type: text/plain
>>
>>> Very much related to this, please see my suggestions for updates to
>>> the GRASS query functions. Most should be relatively minor changes,
>>> but would make querying much easier. And it would make it easier to
>>> implement GUI wrappers for interactive querying.
>>>
>>> <http://grass.osgeo.org/wiki/GRASS_6.3_Feature_Plan> "Updates to
>>> vector querying "
>>
>> OK, good perspective !
>>
>> Concerning the GUI wrapping of commands such as v.what or v.select,
>> will it imply the ability to query directly within the display window ?
> 
> Yes. That's the idea. Martin Landa already has tried to implement this 
> to some extent in the new wxPython GUI. But it involves a lot of 
> workarounds for inadequacies in the GRASS vector querying. These updates 
> to querying modules would make this easier and more robust.

One of the first things that probably needs to be done is to implement 
the spatial index in a file, instead of memory, as already suggested by 
Radim:

http://freegis.org/cgi-bin/viewcvs.cgi/grass6/doc/vector/TODO?rev=HEAD&content-type=text/vnd.viewcvs-markup
("Keep topology and spatial index in file instead of in memory")

Otherwise any vector querying becomes very slow with larger maps.

Moritz