I have a question regarding metrics to measure glare potential, but for an external environment.
I was looking at this page here:
The range of values in this page for imperceptible, perceptible, disturbing and intolerable glare make sense to me. My question is, however, are these ranges still applicable when you shift to an external environment? (I am analyzing the glare potential caused due to a glass tower onto a swimming pool located close to it at a lower level). I would guess that when the sun is out, the external environment is much brighter in comparison. And so I am getting DGP values closer to 0.7 or 0.8. Maybe DGP is not applicable when it comes to external environment? So, what metric would I use to figure out if the tower is actually creating glare? Should I be looking at the contrast among the luminance values in the scene?
Any thoughts would be helpful.
DGP is only applicable for indoor environments, so your intuition is correct. All of the other metrics presented on that webpage are the same, only meant for the indoors.
For outdoor daylit scenes, there is not any great metric (that I am currently aware of). My suggestion is to look for the reflections from the glass on the tower using a series of -ab 0 renderings. If you are only caring about reflections, a method similar to the one we implemented here could be useful. If you need to worry about solar convergence, I would check out this presentation from Stephen Wasilewski.
Thanks a lot, Alstan!