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MisterS
05-04-2010, 09:35 AM
*edit* I forgot to say software: 3DS MAX - and in hindsight, perhaps this is in the wrong forum.

What's the best method for the above?

I have a building with multiple windows. the scene has a daylight system, and internal lighting.

Need to show the building's internal lighting (does not need to be physically accurate though) without completely blowing out the highlights created from the daylight system.

Best so far is to delete the daylight system and use mr spot and standard skylight with grad ramp as background referenced to env slot. I tried a number of adjustments to daylight system but highlights were always blown.

I guess I'm trying to produce a HDR image that has been tone mapped. A fudged version in Max will be better as I don't have photoshop at work, only Gimp, and it doesn't open HDR or EXR files.

sundialsvc4
05-04-2010, 04:24 PM
As a very general statement (taken from real-world photogrphy), you basically can't get an exposure that's going to properly take-in everything at once. But, in CG, you don't have to.

I'd suggest breaking the shot down, then compositing it back up. The lights from outside the window; the shadows they cast (or shadows that plausibly could have been cast); ditto the lighting inside. The "practical light" (where the lamps appear to glow) is distinct from the "contributed light" (my term) that appears to be coming from those lamps.

Every channel of information must be "clean," and distinct. Use a file-format such as EXR which allows you to capture the various channels in a single file. No (lossy) compression; no premultiplied-Alpha. Colors can be pure-white $FFFFFF because you're going to assign new colors (of the right color-temperature) during mixdown.

When you do this, you can now "mix down" the various elements to get just the effect that you want ... and you can make further adjustments as needed by whatever media or mediums you are delivering output to. All of these adjustments now occur two-dimensionally (but with reference to Z-map info...) in the comp. Work from total blackness, adding channels one at a time. Examine the histogram constantly.

That is what's going to give you the control that you want, to get the image that you need. Imagine an infinitely-wide audio mixing board ... You are doing a multi-track (visual) recording.

Study books on studio large-format (yeah... sheet film) photography for ideas and examples. You're going to have to do basically what they do. However... you're not constrained by "the real world." You have the perfect digital photography-studio, the perfect digital darkroom. And you never have to get your fingers dirty, working confidently and entirely "by feel" in dim red light. (Which, in my opinion, is "too bad.") :D

MisterS
05-05-2010, 12:57 PM
Thanks for the response, I don't really have time at work to render multiple passes and composite - partly due to my lack of experience with doing it.

Time allocated for viz work is pretty tight, for example today I have to produce a model and renders of a water pumping station from scratch. Not such a huge task but I definately wouldn't have time to render multiple passes and faff around.

I think I'll settle for ditching the daylight system for now as this has done the trick.

xeltestic
05-07-2010, 09:10 AM
Thanks for the response, I don't really have time at work to render multiple passes and composite - partly due to my lack of experience with doing it.

Time allocated for viz work is pretty tight, for example today I have to produce a model and renders of a water pumping station from scratch. Not such a huge task but I definately wouldn't have time to render multiple passes and faff around.

I think I'll settle for ditching the daylight system for now as this has done the trick.

I would really take sundialsvc4 advice to heart. Ok. I admit his answer sounds like more work, but I guarantee you it WILL safe you loads of time. Maybe not with this project if your deadline is like today. Think about it, how much time it takes to go into each individual lights settings and do test render after test render...argh. You are never gona achieve the result you want. With this approach you can try out a multitude of different things in just a fraction of time. If you don't have time at work to learn it than you should do it in your spare time. You will not regret it.

MisterS
05-07-2010, 09:15 AM
Yeah you're probably right. It's been on the to-do list for a while. I have a big project coming up and it will proably pay off to get this nailed.

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