Tim Saunders Posted May 9, 2006 Share Posted May 9, 2006 I understand this subject has got to be near as hard to understand as any element of rendering, but I'm really stuck here after watching volume II, GI interiors. Chris mentioned with a little frustration in his voice that there would be some that just wouldn't grasp the concept just yet and wouldn't be ready to switch to the first method he discussed about using gamma correction. Sinse everything he said went over my head the first time, I figured I would be one of those. To us he said to just apply 0.454 multiplier in both dark and bright. Then we can render out plain tiffs and see the results in the frame buffer (if I even understood that). I have seen many tips and tricks and tutorials on the web, a couple even on spot3d that recommend using hsv exponential. This has worked great for me in the past to use one of the exponential types, and adjusting the dark and bright multipliers until I get the effect I want (not blown out, yet bright enough in the darker areas). Is this a bad habit? It sounded like a blanket statement to always use gamma correction with 0.454 up and down when rendering tiffs, yet contrary to what you can find on the web. Link to comment Share on other sites More sharing options...
Sawyer Posted May 9, 2006 Share Posted May 9, 2006 Try just .4545 for brightness leave dark at 1. Link to comment Share on other sites More sharing options...
Tim Saunders Posted May 9, 2006 Author Share Posted May 9, 2006 That looks wierd. With either type of color mapping I can adjust the values, but it seems that is a battle of your lighting and the color mapping. My impression fro what Chris was saying is, there is a somewhat true color consistant setting to use all the time. I however really like how when I have a scene that needs to be brighter in the dark areas, I can adjust the dark multiplier and not loose rendering time. My question really is, do I stick with a universal color mapping setting, and adjust my lights if needed (which will cost rendering time), or do I use them both together and adjust the mapping as needed to get the "lightness and darkness" I am looking for? To me it seems like this is anartist interpretation area - no general answer. Link to comment Share on other sites More sharing options...
BrianKitts Posted May 9, 2006 Share Posted May 9, 2006 I never touch the settings... and just leave them on 1.0 linear. and use the curve editor in v-ray.... or you could just leave it set to the .4544 gamma correction I'm yet to understand why anyone plays with the light and dark multipliers. The same effect is gained by controlling your lighting, and level of primary and secondary bounces. It just seems more realistic to me to control your scence that way instead of using a global overide to create a scene.... I guess I just have better luck setting the scene by balancing the lights with the gi... Link to comment Share on other sites More sharing options...
ShaunDon Posted May 9, 2006 Share Posted May 9, 2006 I concur with Brian. We used to use HSV Exponential on all our interiors, and following some discussion on the Chaos boards we'd cranked both multipliers up to crazy numbers like 8x8 and 10x10. I always thought they were supposed to be a ratio, but it's a difference. Trouble is HSV Exponential may save you the burnouts at the expense of realistic color. Lately I've just learned to light more evenly and control my hotspots better at the emitter settings and have been far happier with my results. Shaun Link to comment Share on other sites More sharing options...
Iain Denby Posted May 9, 2006 Share Posted May 9, 2006 I've just been loking at this too. Tried HSV Exponential, and whilst it got rid of burn outs nicely, I found for exteriors it's a bit 'chalky' looking. Also just tried gamma correction in Max to 2.2 and altering my lighting to compensate for the lighter results. Pretty good , but means you have to re-do all your maps, materials and colours too. Might just go back to Linear on defaults until I have time and courage to to deal with the others. Link to comment Share on other sites More sharing options...
Sawyer Posted May 10, 2006 Share Posted May 10, 2006 I think all linear does is give wider range to your greys and their are other methods to do this (fill lights light/dark tweaking). I too think it is a pain to apply the color corrections to every map. I hope 1.5 has it down a little cleaner but I am not sure when I will get my hands on that. But I have seen my images vastly improve since using this method and I do much less tweaking. Real simple example - All of the color mappins is set to 1/1 except gamma which is bright 1 dark .4545. other than that no changes. Link to comment Share on other sites More sharing options...
Iain Denby Posted May 10, 2006 Share Posted May 10, 2006 I think all linear does is give wider range to your greys and their are other methods to do this (fill lights light/dark tweaking). I too think it is a pain to apply the color corrections to every map. I hope 1.5 has it down a little cleaner but I am not sure when I will get my hands on that. But I have seen my images vastly improve since using this method and I do much less tweaking. Real simple example - All of the color mappins is set to 1/1 except gamma which is bright 1 dark .4545. other than that no changes. So do you use gamma 2.2 and then adjust the curve in in the VFB? Link to comment Share on other sites More sharing options...
Sawyer Posted May 10, 2006 Share Posted May 10, 2006 Well I have taken to adjusting the VFB only for high res output. Most of the time I use the gamma correction color mapping and adjust the light dark Link to comment Share on other sites More sharing options...
Christopher Nichols Posted May 10, 2006 Share Posted May 10, 2006 Man... I knew this would be a hard concept to get a grasp of... If you adjust your color mapping you are burning in a color correction into your image. That is fine and good if you don't want to do any comping. If you leave it linear, you need to adjust the curve trick that throb outlines to see it correctly. The problem with what many of you are doing is that you are tweaking color correction in the rendering instead of in the image imaging software (photoshop, after effects, etc...) Link to comment Share on other sites More sharing options...
Tim Saunders Posted May 10, 2006 Author Share Posted May 10, 2006 Man... I knew this would be a hard concept to get a grasp of... If you adjust your color mapping you are burning in a color correction into your image. That is fine and good if you don't want to do any comping. If you leave it linear, you need to adjust the curve trick that throb outlines to see it correctly. The problem with what many of you are doing is that you are tweaking color correction in the rendering instead of in the image imaging software (photoshop, after effects, etc...) Good point Chris. I think I just need to watch the clip 5-6 times and I may grasp the concept. I see what you mean, but putting it into action will require the reviews. Like the save as .hdri thing. I'm not too sure about that whole deal. Link to comment Share on other sites More sharing options...
Parker1 Posted May 10, 2006 Share Posted May 10, 2006 Man this topic has gotten me all twisted around! I have watched that portion of the DVD 3 times, taking notes along the way. I have also read every post I could find on the topic both here and on Chaos. It seems that it is a workflow more suited for true CG work in which no printed output is ever needed (i.e. Film, TV, Video etc). As for me, we print everything we do and the clients make large mounted boards of the images for marketing etc. So to me, burning the corrections in may be the way to go. It seems easier to just render out an 8-bit TIFF, print it in Photoshop, and call it a day. Still confused though.... Link to comment Share on other sites More sharing options...
Tim Saunders Posted May 10, 2006 Author Share Posted May 10, 2006 I agree with you, but it seems like chris mentiones some benefits of saving as an hdri, and allowing photoshop to adjust the levels as it opens. Then you save as your tiff or whatever. Again, still super foggy for me. It may seem like a pain, but then again so is adjusting your color mapping levels. Chris' way just seems a little more consistant--less experimenting needed. Link to comment Share on other sites More sharing options...
Sawyer Posted May 10, 2006 Share Posted May 10, 2006 The thing with HDRI output that is great is that you can play with it a bit more in PS afterwards. If you are going to play play with an HDR. Try it. I used it for the first time recently and it's really nice you have much more flexablity to adjust the exposure once its rendered. Link to comment Share on other sites More sharing options...
Christopher Nichols Posted May 10, 2006 Share Posted May 10, 2006 Everything you guys are saying is correct... so I feel better now. The advantage of HDR output is the flexibility as well as the fact that the color mapping is built in. Photoshop will adjust the color mapping based on your monitor profile. If working in 8bit works for you, great, it is simply less flexible.... and if you are going to work in 8 bit, burning in the color mapping in Vray would be a better solution.... why? because otherwise you woudl have to adjust it in photoshop and since it is 8bit, you would get loose quality doing your CC in there. I am sorry it is confusing... I tried my best on the DVD to explain it. Link to comment Share on other sites More sharing options...
Tim Saunders Posted May 10, 2006 Author Share Posted May 10, 2006 No apology needed. I could tell there was a change in your tone of voice on the recording when you started talking about it just in pure hesitation of the can of worms it would open. It's a good subject that needed the attention you gave it. It could even use more attention, not in that volume of coarse as it isn't the topic of the lectures. However you don't see enough explained on the web, that's why I started this thread. Link to comment Share on other sites More sharing options...
kypuram Posted June 20, 2006 Share Posted June 20, 2006 is the above mentioned theory applicable to walkthru also Link to comment Share on other sites More sharing options...
Tim Saunders Posted June 20, 2006 Author Share Posted June 20, 2006 yes Link to comment Share on other sites More sharing options...
kypuram Posted June 20, 2006 Share Posted June 20, 2006 is the same theory practised for architectural walkthrus Link to comment Share on other sites More sharing options...
Tim Nelson Posted June 21, 2006 Share Posted June 21, 2006 yes yes Link to comment Share on other sites More sharing options...
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