Allow Negative Target Height in Viewshed Analysis (viewshed.py) #812
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Description:
This pull request introduces support for negative target heights in the viewshed function. The modification ensures that target points can have a decreased z-value, which is particularly useful for cases where visibility analysis needs to account for building facades rather than rooftops.
Reason for Change:
When using the library for viewshed analysis from an observer in a tall building, the function primarily returns visible points on rooftops rather than building facades. Allowing negative target heights makes it possible to adjust the z-value of the target point while keeping all other points treated normally, improving accuracy in urban visibility studies.
Fixes #
Proposed Changes
Modified the conditional check in _viewshed_cpu from:
if target_elev > 0:
toif abs(target_elev) > 0