[GRASS-user] Calculating cost to port - now with rail

[Daniel Victoria]

Hi list,

A while ago I asked a similar question about calculating cost to port
considering a road network. I got this sorted out and results look nice.
But now I'd like to include some rail lines in the analysis.

The problem is that if I just add rail lines to my cell cost raster, the
rail lines will be treated as roads, that is, I could 'board a train'
anywhere along the rail line and not only at the stations.

I though about adding a buffer to the rail line with a very high cost (or
null value). But that would fail where roads crosses rail lines. Is it
possible to solve this using r.cost? Or do I need to use some other method,
like v.net?

Cheers
Daniel
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Re: [GRASS-user] Calculating cost to port

[Daniel Victoria]

Wow, that was fast. I was just about to reply the I found out I should put
the ports as starting points. And that is clearly stated in the manual

https://grass.osgeo.org/grass70/manuals/r.cost.html#shortest-distance-surfaces

Thanks all
Cheers

On Fri, Nov 10, 2017 at 2:21 PM Moritz Lennert 
wrote:

> Le Fri, 10 Nov 2017 16:03:45 +,
> Daniel Victoria  a écrit :
>
> > Hi list,
> >
> > I want to calculate a cost of getting from any cell in my raster to
> > some ports, considering roads network, and I though r.cost could
> > solve this.
> >
> > What I have is:
> > 1) Cost raster map with cost per cell (10 for normal cells, 1 if it's
> > a road)
> > 2) vector map containing several ports
> > 3) start_raster has the same extent of the cost raster, but all cells
> > == 1
> >
> > This is the command I'm using
> > r.cost input=cost_map output=cum_cost stop_points=ports
> > start_raster=my_region
>
> Just try it with r.cost input=cost_map output=cum_cost
> start_points=ports
>
> Moritz
>
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Re: [GRASS-user] Calculating cost to port

[Moritz Lennert]

Le Fri, 10 Nov 2017 16:03:45 +,
Daniel Victoria  a écrit :

> Hi list,
> 
> I want to calculate a cost of getting from any cell in my raster to
> some ports, considering roads network, and I though r.cost could
> solve this.
> 
> What I have is:
> 1) Cost raster map with cost per cell (10 for normal cells, 1 if it's
> a road)
> 2) vector map containing several ports
> 3) start_raster has the same extent of the cost raster, but all cells
> == 1
> 
> This is the command I'm using
> r.cost input=cost_map output=cum_cost stop_points=ports
> start_raster=my_region

Just try it with r.cost input=cost_map output=cum_cost
start_points=ports

Moritz
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Re: [GRASS-user] Calculating cost to port

[Anna Petrášová]

Hi Daniel,

On Fri, Nov 10, 2017 at 11:03 AM, Daniel Victoria
 wrote:
> Hi list,
>
> I want to calculate a cost of getting from any cell in my raster to some
> ports, considering roads network, and I though r.cost could solve this.
>
> What I have is:
> 1) Cost raster map with cost per cell (10 for normal cells, 1 if it's a
> road)
> 2) vector map containing several ports
> 3) start_raster has the same extent of the cost raster, but all cells == 1
>
> This is the command I'm using
> r.cost input=cost_map output=cum_cost stop_points=ports
> start_raster=my_region
>
> However, my results is a map will all values equal zero. Is it because the
> stop_points in ports lay inside my start_raster? Thus r.cost reaches the
> stop point right from the start?
>
> My final result should be a map of distance to ports considering the roads
> network.

I think it should be
r.cost input=cost_map output=cum_cost start_points=ports

your ports are the starting points.

Anna

>
> Cheers
> Daniel
>
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[GRASS-user] Calculating cost to port

[Daniel Victoria]

Hi list,

I want to calculate a cost of getting from any cell in my raster to some
ports, considering roads network, and I though r.cost could solve this.

What I have is:
1) Cost raster map with cost per cell (10 for normal cells, 1 if it's a
road)
2) vector map containing several ports
3) start_raster has the same extent of the cost raster, but all cells == 1

This is the command I'm using
r.cost input=cost_map output=cum_cost stop_points=ports
start_raster=my_region

However, my results is a map will all values equal zero. Is it because the
stop_points in ports lay inside my start_raster? Thus r.cost reaches the
stop point right from the start?

My final result should be a map of distance to ports considering the roads
network.

Cheers
Daniel
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