[GRASS-dev] v.what and spatial index

[Trevor Wiens]

On Fri, 08 Sep 2006 09:47:16 +0200
Moritz Lennert wrote:

> Glynn Clements wrote:
> > Moritz Lennert wrote:
> > 
> >> However, v.what does not have an interactive mode (that's the whole idea 
> >> of v.what so it fits better into the GUI). This means that since it 
> >> builds the spatial index everytime you call it, everytime you use the 
> >> query tool you get the building of the spatial index.
> >>
> >> Now, I see several options from here:
> > 
> >> - Change the query tool in the GUI so that it collects points and then 
> >> sends the whole series to v.what. This has the big disadvantage that you 
> >> don't see the results of your clicks immediately (i.e. you "blindly" 
> >> click on a series of points and then push "go" to see the results for 
> >> all of these points). It still means that whenever you resuse the query 
> >> tool spatial index gets rebuilt which can be very annoying if you have 
> >> to query information out of a map. So, even though this might be a 
> >> temporary "solution", I don't find it very satisfactory.
> >>
> >> - Reimplement an interactive version of v.what, or rather make it 
> >> possible to use d.what.vect from the GUI. This would probably mean 
> >> recoding d.what.vect in whatever the GUI language and call GRASS library 
> >> functions from there.
> > 
> > The obvious approach is to extend v.what to allow coordinates to be
> > read from stdin.
> > 
> > BTW, it appears that v.what currently ignores all coordinate pairs
> > other than the first.
> 
> Didn't even try that, but yes. Shouldn't be too hard to implement, 
> though. Trevor, any reason you left this out ?
> 

I simply removed the interactive functionality in d.what.vect which
Radim wrote. Other than that I made only minimal changes to the code.
That could be added however fairly easily. I think however the more
pressing issue is some of the re-write stuff that Radim refers to in
his TODO. At this time, I don't have the familiarity with the vector
library to work on that list of items, sorry. However, once the spatial
index is stored in a file and read as needed, this would eliminate the
need for entering multiple point sets wouldn't it? If however we need
multiple point sets, I'm sure that I could add that relatively quickly
if needed.

T
-- 
Trevor Wiens 
twiens at interbaun.com

The significant problems that we face cannot be solved at the same 
level of thinking we were at when we created them. 
(Albert Einstein)