Hi Craig,
Specular Highlights, so far – are simulations, hence they do not represent the shape of the light (e.g., area, etc). I have discussed this some where. As they are fake, the creation of such should be the same. I will do some tests later this evening of course, to check this based on your specific question, as everything is in flow and I like to re-insure my knowledge rather then talk based from memory. ;o) Currently I have some renders running, so if there is a difference I will report back, later.
If you chose the “TYPE” inside of the Specular, to my understanding, then you get a complete different result for each (why would there be an option if that would be not a given), which means it is a question of quality and not longer one of render-time (primarily). If that was the question, then make a test. So, is the Roughness your concern? How to compare these qualities then to have a good comparison in render-time.
However, this seems to me more an “how to get a fake aesthetically integrated”. Which might work to some degree, but our audience is getting more picky every year… ;o)
Anyway, as I wrote I take a look into it.
All the best
Edit:
The images show the different characteristic of the “roughness”. Which makes it so difficult to compare. Oranges and Apples. There is such a aesthetically difference, I’m not clear if I can follow here. I see speed differences easily, perhaps I miss the question
/edit
P.S.:
So, I went into it, and used 100% roughness and a fixed AA value 2x2 min 2x2 max, 4%. As computer have more and more background work going on, I repeated the test several times. As each computer is different, disk speed/ssd, ram speed, etc. This mix will play into the results of course. (I had overnight a render-job on my laptop, After Effects. While entering the room it told me 9.5 hours left. I stopped it, put it on an eight core machine with a raid-0: 01:50 min:sec. Bang, done. Hence why I don’t even bother to share exact values. Yours will vary anyway.
I do not see a huge difference in the render-time, below 5-20%. Too little to be a concern and to put the aesthetic below render time, at least for me. Anyway, faked Specular is on the way out from my point of view anyway.
Thanks for the question, I would have done a test for this, but now I know a little bit more.
Enjoy the quality of the options we have now!
