[Gvsig_english] Fwd: raster buffer

[Simon Cropper]

On 03/10/12 00:26, Andre Pais wrote:
>
>
> ---------- Forwarded message ----------
> From: *Andre Pais* <[hidden email]
> </user/SendEmail.jtp?type=node&node=5005887&i=0>>
> Date: 2012/9/29
> Subject: [Gvsig_english] raster buffer
> To: [hidden email] </user/SendEmail.jtp?type=node&node=5005887&i=1>
>
>
> Hi there,
>
> So I need to generate a raster theme that represents the distance to the
> road network of a certain area. I started with the shapefile that represents
> the road network, then I converted it to raster using "rasterize vector
> layer". Now, I need to use a function that makes buffers to the road network
> similar to "Euclidean Distance" of Arcmap. I´ve tried "raster buffer" of
> Sextante but it doesn´t return what I need. For example, in the function´s
> options I defined my input (the road network raster) and the buffer distance
> as 100 (my cell size). The output varies from 0 to 2 and I cannot understand
> what it represents nor its appearance looks minimally similar with what I´ve
> done with Arcmap.
>
> I would bery much appreciate an answer
>
> Regards, André Pais.
>
>
>
[snip]

André,

Is this what you are trying to do?

Using Sextante...

1. Buffer road (1 concentric ring at 500m)
2. Convert buffer from Polygon to Polylines
3. Merge Line Layers and simplify
4. Assign Double Number representing distance (0 for road, 500 for buffer)
5. Convert Merged Line Layer to Raster, i.e. {Rasterize vector layer}
6. {Void Filling}

Gives you a raster, similar to a DEM generated from contours but instead 
of elevation you are using distance from road as the variable.

-- 
Cheers Simon

    Simon Cropper - Open Content Creator

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