First a broad question to stir up any words of wisdom, papers, and presentations, that I might have missed… and a few more specific questions mixed into my thoughts about each phase method below.
Let’s say you have a room model that has various obstructions, say inside there’s a combination of ductwork, various height office furniture, and columns near and far from windows/skylights. And exterior there’s another building that influences sun patterns on your window or skylight. If you don’t have a need to interchange dynamic BSDFs or parametric facade option matrices, is there much accuracy benefit to the 3,4,5, or 6 phase methods if you can use the 2P+DDS method for solar accuracy as described in Sarith’s tutorial? Does each extra phase actually add more model and script setup time, and also add potential errors in how you break up sender/receiver surfaces around obstructions?
My take on calculation method options:
Simple 2-phase - won’t give precise sun effects, but requires simplest model setup and simplest calc routine. Can slightly improve sun effects using e.g. r4 sky subdivisions. If you used more sky divisions like r6 or more, and very high -ad does this get closer to solar accuracy of the next option, or too high risk of rays missing the tiny sun patches?
Enhanced 2-phase with direct suns (Two-Phase DDS Version in Sarith’s tutorial) - adds precise sun effects, needs a little more scripting and splitting the glazing out of the model to make black surface models, takes more time to calculate all the suns. Is the r4 still beneficial or just risk of missing smaller patches in the DC or blackened model ray tracing? And do you only need -ab 1 and higher -ad /edit: for the direct sun calculation/ if you have trans or static-BSDF glazing materials to ensure rays get to those surfaces, and through them? I noticed Sarith’s tutorial uses -ad 256 but Andy’s 5-Phase tutorial used a much higher setting.
Standard 3-phase - Correct me if I’m wrong, but with varying obstruction locations, you’d need to split your sender/receiver glazing into pieces by proximity to obstructions - complicating the script and model setup. Any thoughts on time or accuracy benefits (compared to “2P+DDS” method) versus this next step of modeling/scripting hassle? You actually lose accuracy of sun effects until you get to the 5-Phase method, even with r4 or similar sky subdivisions. The primary benefit would come if you had many interchangeable options to study or dynamic shading/glazing system with BSDF, correct? But even then you might need to go to 5-Phase if the peak sun values are important.
4-phase - if you need to add proxy surfaces around thicker external shading geometry. In this case you’d have even more levels of complexity if you’re breaking both external layer of proxy surfaces and internal layer of glazing into pieces based on external and internal obstructions.
5-phase - would add back in the solar accuracy, but if you’re breaking up internal and external sender/receivers around obstructions, you also now have to manage regular and black versions of the models for various sender and receiver flux matrix combinations.
Please comment wherever I’m missing considerations. Thanks, Chris
PS, sorry for the length - didn’t realize it until i hit the “post” button!