[GRASS-user] The algorithm r.cost is not working

[Markus Metz]

On Wed, Feb 22, 2012 at 11:31 AM, Elisa Solano Villareal
<villareal at fbk.eu> wrote:
> Thanks for your answer.
>
>> The cost surface used as input
>> for r.cost must have only positive values, negative values will cause
>> infinite loops. Please make sure your input cost surface has only
>>positive values.
>
>  but we have seen our data and it doesn't have negative values, the minimun value is 0.

I am not sure if a cost of zero is valid or if the algorithm of r.cost
(Dijkstra search) does not allow zero costs. If you regard costs as
e.g. travelling times, the time needed to traverse a cell, then zero
would not be possible, because even if the time needed to traverse a
cell is very short, it is always larger than zero.
>
>> r.cost has changed a bit lately, in particular since GRASS version
>> 6.4.0. Please use 6.4.2 if possible.
>
> We did it but.. we found this message r.cost: malloc.c:4471: _int_malloc: Assertion '(bck->size & 0x4) == 0' failed.
>
> Please, can you give more information.

I would need the input cost surface, the starting points, and the
exact command used in order to reproduce the problem.

Markus M

>
> Thanking you in advance,
>
> Elisa
>
> ________________________________________
> From: Markus Metz [markus.metz.giswork at googlemail.com]
> Sent: Tuesday, February 14, 2012 12:39 PM
> To: Elisa Solano Villareal
> Cc: grass-user at lists.osgeo.org
> Subject: Re: [GRASS-user] The algorithm r.cost is not working
>
> On Tue, Feb 14, 2012 at 11:56 AM, Elisa Solano Villareal
> <villareal at fbk.eu> wrote:
>> Hi there,
>>
>> I have a question, I am working with r.cost algotithm but is not running for my whole spatial data but when a put just a piece of the map it works.
>>
>> The main problem is that the algorithm does not finish, but it seems as keeping running 112%, 115%,120%...
>>
>> My version is 6.4 and the bigest cost raster size is  6085, 6823 for the starting points are 1727.
>
> r.cost has changed a bit lately, in particular since GRASS version
> 6.4.0. Please use 6.4.2 if possible. The cost surface used as input
> for r.cost must have only positive values, negative values will cause
> infinite loops. Please make sure your input cost surface has only
> positive values. If the problem persists, it would be great if you
> could provide a sample script and/or sample data to reproduce the
> problem. At least in 6.4.2 r.cost is working fine.
>
>>
>> Grass showed also this message: Dev note: Adapted sites library used for vector points. (module should be updated to GRASS 6 vector library). As the matter of fact, we are no sure if it is the real problem.
>
> No, this is not a problem.
>
> Markus M
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