You are right that it messes up the rendition of a photo, such as used on an EnvSphere. To get the photo directly out as is, you would have to anti-ETM the photo!!! LOL Nobody but us will do that.

But outside of the EnvSphere or reflection map issue, ETM is easier for an "artist" to deal with. Too dark? Increase exposure. Too light? Decrease exposure. Artists will not ponder the math. They will tweak and test render for days. I, on the other hand, will compute the right formula and produce an accurately lit render in the first try. I will also use that formula over and over, because I do not make inconsistent shaders. My components all behave as much as possible to the standards set by reality, which means I'm not having to guess-and-test very much as different element of fhe scene appear out of whack.

Only reason I'm posting these details, is so that people who do not want to waste time can benefit from the experiments, and learn from them, and because I was asked to do so in a couple PMs. For the artists, they should skip the formulas, and just look at the test renders, see which they like best, and copy the two numbers I used, and move on. Copying two numbers does not require a PhD in math.

Some people are actually insulted/irritated by my technical postings and have said so. They can go fuck themselves.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)