Tyson Logo Keychain experiments

[mzungu]

I'm not sure this is so much a "finished project" as a test of different settings on the same scene. I'll try to describe the differences properly, but I'm a noob and have more questions than answers...


This was created using 0.6 test 1 with 2 threads run over the weekend (60+ hrs) at twice this rez (1440 x 960). It is set inside an enclosed box with two mesh lights & nk metals (au & ag).


This version went back to 0.5 (due to probs with env_maps I was having on 0.6) and basically removed the cube enclosure replacing with the Uffizi HDR. Only minor other changes were made, most notably the exponent on the keychain pieces. It was also run for less time with only one thread.


This version is shown mostly for contrast with the other versions, as it was obviously only rendered for a short time. The only change here was to switch to the Kitchen Probe HDR. The lighting becomes much more dramatic, I think, but not totally satisfactory, so...


This version was my attempt to pump some more light into the above version. I start with boosting the <gain> from 0.0004 to 0.4 on the <spectrum><blackbody> portion of the meshlights. Well this basically blacked out the rest of image - not at all the desired effect. So next I tinkered with the <temperature> of the above tags and after some tweaking, eventually came to this point. To get this I also had to boost the gain on the env_map to 2.5 to get it to effect the scene as much as it does here. I'm thinking the <blackbody> option is not the best way to go on these meshlights. I'm just not clear on the options available and what all they do (in layman's terms.) I'm still not that pleased with the lighting on this one. Its hard to get this stuff right! (But kinda fun to tinker with, eh? )

Previous blender and yafray renders of this scene can be viewed here.

Any thots to contribute, or crits or ???

[rusted]

hi ,

first render is good.for me the wood grd is distracting(also v familiar)/maybe a sober grd?

[mzungu]

Thanks for the comments, rusted. I agree about the table texture. Its standing out more than the actual subject of the shot... Oh, well. Its not really intended for anything other than a lighting excercise, really.

Here's another version:

I tried switching from <blackbody> to <peak> for the spectrum of my meshlights and pumped up the <peak_value> from what the documentation page said to use (500, I think.) to get the brightness that I wanted. This version loses some contrast, which makes it less interesting, I think. But at least my subject matter is lit somewhat better. To get the appropriate contrast, I'll have to take rusted's advice and use a different background. Maybe I'll play more with that when I get some free moments... - For now, its done.

[Beltane]

[mzungu]

radiance, you exhibit more wisdom when you're drunk than I could ever show when I'm sober! Rock on!

So is Indigo designed so that the <blackbody> spectrum type sort of "saps" the environment of competing lightsources? (for lack of a better way of saying it...) It was a very interesting effect, when I cranked the <gain> on it: all the other sources of light seemed to go dark/black. Not quite sure what this means.

[OnoSendai]

What's happening is that the (Reinhard) tonemapping automatically maps the image so that the whole image is 'exposed' correctly. (e.g. maps the brightest white to rgb(1,1,1)) So if you have one light in your scene, and you make it twice as bright, the render should look exactly the same. But if one light is much brighter than another light, that light will dominate, and the scene will be 'exposed' for that light.

If you want to see the effects of changing light intensities more directly, try using linear tonemapping, which doesn't do automatic exposure.

[mzungu]

Thanks, Nick! That explanation clears up what's been happening (and actually makes sense to me! Its kinda like what happes on a digicam when you point it quickly from a shaded area into a sunny one, right? )

So, I'll do some digging in the ini files and the XML to see where this tonemapping thing can be switched over...