Jack de Valpine wrote:
Hi Giullio and others following this thread,
<RANT MODE>
It seems to me that this is a problem with proprietary shrink wrap software renderers. Who really knows what is going on under the hood, whose word should be taken for the validity of the physical model, what validations have occurred?!
Users see the product marketing materials that talk about Global Illumination and "physical accuracy," and they believe the hype! That seems to me to be pretty dangerous if you are going to be using the tool to somehow "validate" design issues!
Can I get an amen-ahh!
I got into it with a CAD/modeling pundit several years ago, when he stated in a review that Viz was capable of producing renderings that were "95% accurate". What the hell does that mean? Well, I asked him, and he said he spent a full day with Stu Feldman (one of the two founders of Lightscape), and that was what he walked away with. I told him he didn't get his money's worth on the half-day seminar. We went back and forth on this, I told him he was doing his readers a great disservice, and in the end I was made to feel like a loser for being in such a small industry that no one cares about. Something about "if you want to stick with Lightscape, good luck, it's not going to be supported anymore, blah blah..." The good news is, it forced me to finally learn Radiance. =) The problem is that that review went into Cadalyst magazine, which is read by lots of Architectural CAD drafters and renderers, and as you mention they aren't necessarily concerned with the goings on under the hood. And then you have people showing renderings to clients and saying "oh yes, that's what it will look like, we used software that's 95% accurate!" Which is amazing, since many of these people driving the program don't know how to read a polar curve on a luminaire cutsheet. Oops.
I know that there are systems that have implemented GI to varying degrees and sophistication. But the problem is you probably have to be an uber expert to use them and/or code up custom material/lighting shaders. Still though the question is what validation has occurred. I think that most commercial renderers and users of said systems are really not that interested in physical validity, they are most interested in the outcome/appearance of the final image. It does not really matter how it get there.
...and if the result looks nice in half the time, screw accuracy. That was a lot of the complaining I saw on the M-R forums, was how slow it was. It's comments like that that really give you insight into how little these people understand the problem of solving GI.
It seems to me that the one commercial product that showed some hope in its original (pre-acquisition) form was Lightscape. However, Rob Guglielmetti has explored and written pretty extensively on this topic seemingly with only partial satisfaction (my apologies to Rob G. for such a cursory summary, he did some really excellent work on this). Note I also believe that the original developers of Lightscape were truly interested in enabling people to use a tool with a reasonable and practical level of physical validity.
</RANT MODE>
Thanks Jack. I was merely trying understand the product's limitations because I wasn't ready to commit to learning radiance in production. =8-) And you are right about the developers. At least in the case of Rod Recker (the other Lightscape developer), I definitely felt like he was interested in giving the world a tool. Sure, getting rich off it is a nice bonus, but he seemed to be interested in taking that Cornell education and channeling it into a lighting tool. He's a really nice guy and wish him the best of luck at Autodesk. It's truly unfortunate what happened to that product, but then again it was severely limited in what it could do. Of course, who knows what it'd be like today had the right people stayed in the decision-making seat. Then again, how far can one go with radiosity? (Well, I guess the folks at Lighting Analysts can answer that one, and the answer is "pretty damned far". Their AGI product continues to improve, and with people like Martin at PSU doing validations with it, it becomes more and more robust. But I still prefer Radiance.)
Interesting thread; sorry for the somewhat off-topic verbiage, but I think we all learn from these exchanges too.
- Rob Guglielmetti
