[gdal-dev] Off-topic: speaking of viewsheds....

[Scott]

The following viewsheds were created with GDAL, one tif for every tenth 
of a mile along the 2,650 mile Pacific Crest Trail. Stitched together 
with ffmpeg:

https://youtu.be/tmY27ZIVfpA


On 7/7/23 12:17, Tamas Szekeres wrote:
> Benoît,
> 
> As far a I can understand - depending on the elevation model actually 
> used - you may get different results when changing the observer and the 
> target height or the observer location. I'm not sure how it would be 
> different if you set the target height specifically to the observer and 
> the observer height to the target height.
> 
> Best regards,
> 
> Tamas
> 
> 
> 
> 
> Benoît DesRochers <Benoit.DesRochers2 at usherbrooke.ca 
> <mailto:Benoit.DesRochers2 at usherbrooke.ca>> ezt írta (időpont: 2023. 
> júl. 7., P, 19:21):
> 
>     Hello there,
> 
>     Long story short, I'm trying to generate a viewshed for every cell
>     in a raster and add them all up to get a new raster that would
>     represent how many pixels can be seen from every cell. It takes a
>     while, but it works!
> 
>     The problem is that I'm using non-default observer and target height
>     values (2m observer and 0.5m target) and the results are
>     significantly different when I invert them (Use the target height as
>     the observer and the observer as the target height). From what I
>     understand, most viewshed algorithms don't compute sightlines for
>     every cell but use a reference plane instead and I'm thinking that
>     might be where the problem comes from but I'm not sure.
> 
>     Am I doing something wrong or is that an expected outcome?
> 
>     Thanks,
>     Benoît
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