Author of Proposal:
Harrison K

Reason or Problem

For a given observer location, I would like to know at what height a given observable point is visible.

Proposal

viewshed() would take another parameter in addition toobserver_elev, that specifies amax_height to calculate to, if themax_height is less thanobserver_elev a value error is raised. When each point's visibility relative to the observer is evaluated, the function would iteratively check against increasing values until themax_height.

Design:
A new optional parameter ofmax_height would need to be added, another for step size could also be added to specify by how much the height should increase for each iteration of recalculation. After comparing a given points angle, if the point is determined to be invisible, the height will be incremented and then the angle will be recalculated and compared again. I am still not sure on the best way of storing the height results.

Usage:
User would provide amax_height parameter, without this parameter the current functionality will remain the same.

Value:
User's ofviewshed() would have a way of leveraging the existing calculation capabilities, while expanding giving them the ability to run calculations for multiple observer heights simultaneously.

Stakeholders and Impacts

I am happy to develop this feature myself after getting some more input, specifically on how the results should be returned. For those already usingviewshed() this feature should not impact their use at all. Onlyviewshed() will be impacted.

Drawbacks

Iteratively checking heights could cause significant performance slow downs for large height ranges.

Alternatives

I could just iteratively callviewshed() at different observer heights.

Unresolved Questions

How results of the height analysis would be returned. One idea I had would be to return another DataArray where each point is the height at which the point is visible to the observer and NaN for invisible.

Additional Notes or Context

I am happy to develop this feature myself if it seems reasonable, I would definitely want a bit more guidance on implementation specifics.