271 reputation
213
bio website arencambre.com
location Dallas, TX
age
visits member for 4 years, 1 month
seen Oct 26 at 23:14

Jul
2
awarded  Curious
Dec
4
awarded  Notable Question
Oct
4
awarded  Popular Question
May
11
comment What is the best way to join lots of small polygons to form a larger polygon?
Not sure your syntax is correct. Per postgis.net/docs/ST_Union.html, there is no signature that accepts a number in the 2nd parameter.
May
7
awarded  Popular Question
Jan
21
awarded  Nice Question
Jan
18
awarded  Citizen Patrol
Dec
20
comment MapGuide or Mapserver for Enterprise?
I guess what I was getting at is which is easiest to set up or maintain. Some of these GIS tools are still immature and over-complicated.
Dec
9
asked How to filter or query data in GRASS?
Nov
25
accepted How do I compute v.kernel maps in less than 16 hours?
Nov
25
comment How do I compute v.kernel maps in less than 16 hours?
Just want to confirm that r53983 of 6.4.3 converted the almost-a-day execution into 25.5 minutes!
Nov
24
comment How do I compute v.kernel maps in less than 16 hours?
Is this the same as the v.kernel improvement you put into r53982 and r53983?
Nov
20
comment How do I compute v.kernel maps in less than 16 hours?
Thanks. I'm looking at R mainly, and looks like I might have to mostly spin my own algorithm. I'll keep investigating.
Nov
18
comment Help needed with the rendering of QGIS Heatmaps
Did the lower SD affect processing time?
Nov
18
comment How do I compute v.kernel maps in less than 16 hours?
Do you know of any products that use this faster algorithm?
Nov
17
comment How do I compute v.kernel maps in less than 16 hours?
Yup, I think line 403 is where it traverses the output grid and then does spatial queries to see who is nearby--if I'm reading correctly.
Nov
17
comment How do I compute v.kernel maps in less than 16 hours?
That is an interesting article. Seems like input-centric has advantages where you don't have a good index or when you have far more points than output grid squares, but that's beside the point, I guess, since you found great speed advantages with the FFT. Regrettably, my math education doesn't extend beyond a Mathematics BA, so this is challenging. Anyway, the comments in v.kernel's main.c (trac.osgeo.org/grass/browser/grass/trunk/vector/v.kernel/main.c) indicate use of a "moving kernel", so I wonder if GRASS uses the output-centric method?
Nov
16
comment How do I compute v.kernel maps in less than 16 hours?
Concerning your comments about algorithm efficiency: I'm not sure kernel density maps are as fast as you think? I've also tried with Quantum GIS's built in heatmap feature, and it's even slower. And conceptually, this seems like an O(n^2) difficulty problem?
Nov
16
awarded  Critic
Nov
16
comment How do I compute v.kernel maps in less than 16 hours?
Correction: it's taking closer to 25 minutes to do the v.kernel on the high resolution small area.