Thanks Stefan

It seems first of all v.out.ascii is slow. Following your proposaI, the tmp-file has only 5300 observations after 9min15s. As I have 650.000 points this export will need approx. 18h! Can I speed this up somehow? (Database-driver is dbf)

Patrick

P.S. g.region -up & v.info are given below.


##g.region -up
projection: 99 (Swiss. Obl. Mercator)
zone:       0
datum:      ch1903
ellipsoid:  bessel
north:      1297000
south:      1074200
west:       2484400
east:       2834800
nsres:      25
ewres:      25
rows:       8912
cols:       14016
cells:      124910592

##v.info
 Number of points:       647957          Number of centroids: 0          |
| Number of lines: 0 Number of boundaries: 0 | | Number of areas: 0 Number of islands: 0 |
 | |
 |   Map is 3D: No                                               |
 |   Number of dblinks: 1                                                |
 | |
| Projection: Swiss. Obl. Mercator |
 | |
 |               N:           1294822    S: 1075554                 |
 |               E:           2831184    W:           2486245


On 30.07.2015 13:59, Blumentrath, Stefan wrote:

Hi Patrick,

From my experience r.in.xyz is very fast.

How many points are you processing (v.info pt) and what are your region settings (g.region –up)?

In order to find out where time is spend yo could split upt the process into two steps:

v.out.ascii input=pt output=./tmp column=VAL

r.in.xyz input=./tmp z=4 output=pt method=sum

Cheers

Stefan

*From:*grass-user-boun...@lists.osgeo.org [mailto:grass-user-boun...@lists.osgeo.org] *On Behalf Of *patrick s.
*Sent:* 30. juli 2015 10:18
*To:* Markus Neteler
*Cc:* GRASS user list
*Subject:* Re: [GRASS-user] v.to.rast

Markus

I tested the approach you proposed, but seems to be very slow for large datasets: I am processing ~1000.000 points of observation on a 25m-Grid across Switzerland, where only few cells have multiple points inside. While /v.to.rast/ takes a few minutes for conversion, the combination "/v.out.ascii input=pt output=- column=VAL | r.in.xyz input=- z=4 output=pt method=sum/" has been running for multiple hours and is still in progress.

Is there any alternative to run this conversion? I need it to run neighborhood analyses as kernel density with population field, i.e. /r.neighbors in=pt out=pt_dens -c size=300 meth=sum/. Maybe there is an approach to directly use the vector data and avoid conversion- something as /v.neighbors meth=sum/?

Thanks for you help,
Patrick

On 24.07.2015 04:13, Markus Neteler wrote:

    On Thu, Jul 23, 2015 at 11:00 AM, patrick s.<patrick_...@gmx.net>  
<mailto:patrick_...@gmx.net>  wrote:

        Dear all

        I am puzzled on the behavior of v.to.rast. When several points fall 
into one

        gridcell, the raster seems to get one value but not the sum of these. Is

        there a way to sum these up instead?

    Yes. I have added a related example here:

    
http://grass.osgeo.org/grass70/manuals/v.to.rast.html#convert-vector-points-to-raster-with-raster-cell-binning

    (while it does not really fit to that manual page it is expected

    there. Perhaps we need to really enhance v.to.rast to do such a job

    right away).

    HTH

    Markus


_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

Reply via email to