[gdal-dev] Viewshed potential issue?

[Tamas Szekeres]

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> 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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