[GRASS-user] Unable to get an horizon from a DEM using r.horizon

[Mathieu Monney]

Thanks for the answer.

However the command you proposed are really time consuming as there  
computing the entire viewshed. I only need the last visible points  
from a given position. Do you know any other option to do that?

Thanks.

Mathieu


Le 28 août 2009 à 03:57, Hamish a écrit :

> Mathieu Monney wrote:
>> My goal is to extract the visible horizon given a point
>> using a DEM I have successfully imported into GRASS. Using
>> the r.horizon command it returns me some good result for
>> some part of the horizon. However at some other angle in
>> returns me the 0 value which means that no horizon has been
>> found. I cannot understand why we cannot found a horizon.
>> There always be an horizon, even if a point lies on lower
>> altitude than you. I have tried to modify the r.horizon
>> command to return horizon values which are also below you
>> but it doesn't work well and returns me some weird results.
>>
>> Anyone having some clues about that?
>
>
> not directly, but you might try the r.los module, or r.viewshed from
> wiki addons.
>
>
> Hamish
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