[GRASS-user] v.surf.rst limitations?

[Michael Perdue]

Hey Roberto,
Can you tell me more about this bug? I ran a tile through v.surf.bspline that was significantly larger than this and I never ran into any problems. Nor can I find any defects in the output.
GRASS 6.2.0 (Mudflats):~ > r.info map=BSP_FF
 +----------------------------------------------------------------------------+
 | Layer:    BSP_FF                         Date: Sun Dec  3 18:53:28 2006    |
 | Mapset:   temp                           Login of Creator: maperdue        |
 | Location: Mudflats                                                         |
 | DataBase: /mnt/Storage1/grass                                              |
 | Title:     ( BSP_FF )                                                      |
 | timestamp: none                                                            |
 |----------------------------------------------------------------------------|
 |                                                                            |
 |   Type of Map:  raster               Number of Categories: 255             |
 |   Data Type:    DCELL                                                      |
 |   Rows:         6878                                                       |
 |   Columns:      4798                                                       |
 |   Total Cells:  33000644                                                   |
 |        Projection: UTM (zone 10)                                           |
 |            N:    5275187    S:    5268309   Res:     1                     |
 |            E:     584612    W:     579814   Res:     1                     |
 |   Range of data:    min = 3.222074  max = 250.353352                       |
 |                                                                            |
 |   Data Source:                                                             |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |   Data Description:                                                        |
 |    generated by v.surf.bspline                                             |
 |                                                                            |
 |                                                                            |
 +----------------------------------------------------------------------------+

This grid was 33mil cells with ~30mil input data points.

However, I do receive a seg fault when I try to define a set of sparce data nodes to be interolated (input_ext=).

Cheers,

Mike

PS Yes, v.surf.bspline is much faster than v.surf.rst. But more importantly, it seems to step through the data to prevent memory allocation errors. Is this true? Nice!!! :-)

Roberto Antolin <roberto.antolin at polimi.it> wrote: Hi Carlos and Mike,
At this moment, there is actually a limitation with v.surf.bspline. 
There is a bug and I think it is no possible working with 13.5 mill 
cells. I'm working on it, but by the moment It will reach only 4mill 
cells. Yes, I know it is no enough, sorry. I hope that in a near future 
this will be also fixed. Maybe, if you try with a lower resolution 
(about 20m) v.surf.bspline should work.

However, I think v.surf.bspline will be faster than v.surf.rst. ;-)

Regards,
Roberto.

Michael Perdue ha scritto:

> Carlos,
>
> To the best of my knowledge, the only limitation on v.surf.rst is 
> imposed by the limits of your hardware. IE, your probably running into 
> memory allocation problems. You can try increasing your swap space, 
> but be aware that v.surf.rst will take a painfully long time to 
> process that many points. Alternately, I'd recommend you give r.in.xyz 
> and v.surf.bspline a try.
>
> Cheers,
>
> Mike
>
> On 4-Dec-06, at 3:49 AM, Carlos "Guâno" Grohmann wrote:
>
>> Hello, I have this LIDAR dataset with abou 5.5 millions points that I
>> imported with v.in.ascii -ztb, and I want to interpolate in a DEM with
>> 5m resolution, which gives me about 13.5 million cells. When I try to
>> run v.surf.rst (GRASS 6.3 cvs), it get killed after 30-40 minutes. Is
>> there a limitation on v.surf.rst?
>>
>> thanks
>

-- 
Roberto Antolín Sánchez
Politecnico di Milano – Polo Regionale di Como
(Laboratorio di Geomatica V2.8)
Via Valleggio, 11 – 22100 Como, Italy
tel: +39 031 332 7533 || fax: +39 031 332 7519 
email: roberto.antolin at polimi.it



 		
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