A few questions about Bryce 7.1
videogamer555
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Last version of Bryce I used was Bryce 4. Now in Bryce 7.1 I notice a ton more features. Not sure which are new specifically to Bryce 7.1, and which were added in versions 5 or 6 or 7.0. But these are all the new features that were not in the last version of Bryce I used, and I have questions about some of these these features were not answered in your massive PDF file located at http://docs.daz3d.com/lib/exe/fetch.php/artzone/pub/software/bryce/bryce_7_ag_wip_0204.pdf
What do the 5 lighting options do:
TA Legacy Mode
TA Focused Scattering
TA Scattering Correction
Boost Light
Reflection Correction
What does the new material setting called Displacement do?
What does the new material setting called Anisotropy do?
Is there any way to bounce actual light off of a surface to make it illuminate something? I notice images appear reflected off surfaces, when the Reflection material setting is used for an object. But I can only reflect images (the surrounding scene). I can't reflect an actual beam of light. If I take some kind of directional light (such as spot light, or parallel light) and aim it upward, and place a highly reflective surface above it (turn the Reflection on the material all the way to 100 to make it mirror-like), the light should bounce off the reflective surface, and illuminate the ground below. Unfortunately it doesn't. Is there a setting in Bryce to make it do this? If not, is this a planned feature for a later version? If not, any DAZ software devs who happen to be reading this forum, please consider this forum post as a suggestion for a feature for you to add later, and strongly considering adding it. I am hoping to use Bryce as an accurate 3D optics simulator for demonstrating optical principals like reflection, refraction, etc, and need to be able to not only simulate optical effects on images, but also simulate optical effects on light rays.
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@videogamer555 - welcome to Bryce 7.1 and these forums. Lots of questions, you have quite a bit to catch up from Bryce 4.
- TA Legacy Mode: forget it. It was included for earlier versions of True Ambience that worked on the Ambience channel. It was not very good but a first attempt to global illumination. It's only good to re-render older source files.
- TA Focused Scattering works only if True Ambience is enabled when rendering Premium.
- TA Scattering Correction works only if True Ambience is enabled when rendering Premium. You'll want to enabled that one in most cases.
- Boost Light boosts light beyond the max and this can be used to overdrive colours.
- Reflection Correction makes sure reflections are where they should be.
- Displacement displaces geometry of an object. It doesn't work correctly yet. Bryce crashes when using it, except if Render Priority is set to Low.
- Anisotropy can be used to get radial patterns, the surface changes in appearance as it is rotated.
Bouncing light off a surface works in TA (True Ambience), TA is GI in which light passes between near objects. A mirror receiving light can cast this light (attenuated) onto an object, though it's a bit tricky to set up. I have a video plus transcript of a "Magic Mirror" on my website (see sig). Go to Bryce Documents > Videos > Horo and scroll down to More Videos, #13.
Optical effects are limited in any raytracer. Prisms don't work. On the other hand, refraction indices work nicely - even to the impossibility of an index of 0. Lenses can be made, we've done tele lenses, fisheye lenses, even one for anaglyphs that renders displaced red-cyan images in one go. Keep in mind that 3D CG cannot copy nature, most of it has to be cheated. Whether other programs can emulate all optic properties, I don't know. To my knowledge, even Octane cannot, but my knowledge is limited.
It is unfortunate that the Bryce 7.1 documentation was never finished, though a great part of it is up to date and the PDF you have is a help. A lot of tutorials were made that could help you. I recommend to have a look at this sticky thread: http://www.daz3d.com/forums/discussion/2839/.
This is what I'm talking about. Here's a quickly drawn up diagram I made comparing the existing True Ambiance feature to my suggested feature that I would call True Reflection.
http://i.imgur.com/VuqVT1l.png
@videogamer555 - exactly. The left part TA works as the drawing shows, light reflection doesn't work the way the right drawing shows (and is how it works in real life). It can be made to work somewhat if using a magical mirror.
The image below shows at left how the raytracer usually behaves. The sun is in the back of Vicki and her front in the mirror is dark because the mirror doesn't reflect light the way a real mirror does.
The picture at right shows that the mirror does reflect the light from the sun onto the front of Vicky. There is no light source behind the mirror - the usual hack. The mirror does indeed reflect the light in a way your right drawing depicts. It's a special way how TA is used to make the raytracer also trace light.
Can you explain how you made the mirror?
Horo has already given you a quick description of these tools. I can easily imagine however how a little more specific information might be necessary to get you going.
First is True Ambience. TA was added during the Bryce 5 development cycle at Corel. It was a first attempt at a legitimate Radiosity engine for Bryce. However instead of basing the surface interactions on the Diffuse Channel colors and intensities, TA back then used the Ambience Channel for input. This meant that if you wanted a surface to reflect the environment it also had to be given a glow....which usually spoils the entire point of bouncing light off the surfaces in the first place. It was just bad, it wasnt aimed at realism it was aimed at faster rendering.
There were other bad choices as well which further lowered the accuracy of TA renders. When the "feeler" rays were being fired from a point on a surface into the rest of the scene one would assume that statistically speaking these rays can travel along any allowed pathways without prejudice. But instead there actually was a bias applied to the ray firings such that more rays were fired along 90 degree angles and fewer rays were sent along the remaining angles. This had the effect of concentrating the indirect light in a scene making items appear brighter. But it also gave surfaces what appeared to be a specular shine due to the missing light along certain angles. True ambience lit surfaces literally appeared metallic or "wet" due to the ray firing fiasco.
And if all that wasnt bad enough, there was another all too awful issue that gained Bryce that dreaded "flat looking renders" thing we used to hear all the time. Apparently to save on render time, TA used to apply a "clip" of sorts to the resulting colors of surfaces. Instead of allowing a pixel to be any color TA originally allowed only a defined range of values for pixels. If a pixel value exceeded or fell below the allowed threshold, the surface color would be tweaked at the last moment so that it indeed fit inside the allowed range. This had very odd effects, but one of them being that shading was off (full blacks weren't really allowed) and most colors were not as true and saturated as they should have been, it was almost as if some degree of gray was mixed in. I imagine this was done to limit noise in the final input. If you limit the values allowed on a pixel then the likelihood that two adjacent pixels will be so different in color that it becomes noticeable as noise is greatly reduced. In the end it all comes down to the time needed to calculate each ray. More rays means more accuracy which means more time to render. The thought process by the developers back then was speed over accuracy, and speed meant getting the scene rendered using as few rays as possible....thus the multiple cheats listed above to compensate for the missing rays.
Bryce 7 development completely re-examined all those cheats and did away with them...but backward compatibility was also conserved. Thus the purposes of the following tools:
TA Legacy Mode: Allows the user to revert TA from accepting inputs from the Diffuse Channel back to the old way of accepting inputs from the Ambience Channel. As Horo states, this old method offered nothing in terms of added accuracy but the option needs to be there to retain backward compatibility with scenes made in previous versions of Bryce.
TA Focused Scattering: Again to retain backward compatibility, the user is allowed to reinstate the "Focused Scattering" which was the name given to the badly implemented scattering of the original TA that sent rays along preferred angles unfairly while ignoring other angles.
TA Scattering Correction: This is the new scattering algorithm that fairly distributes the light feeler rays producing much more accurate results. This should be turned on by Default I believe. Unless you want wet looking surfaces, always use Scattering Correction.
Boost Light: Don't let the name mislead you....Boost light doesnt truly boost anything. Boost Light simply removes the arbitrary "clipping" that occurs with colors so that true colors are revealed. This tool is essential for working with True Ambience and IBL in tandem. Since IBL uses High Dynamic Range color information, without Boost Light being enabled TA cannot bounce the true color values of the hdri because many of them would fall outside the limited allowed range. Boost Light is a correction of sorts, applying it makes the final render more accurate and less biased.
Reflection Correction: This tools isnt so much TA based as it is general rendering. It relates to the way bump mapping and reflection work together. There are situations where a surface can have extreme enough bumpiness that some rays end up being reflected back toward the models surface and away from the eye of the camera. This results in a black pixel in the final render. To avoid this we have the Reflection Correction tool that somehow gets those lost reflection rays to find the camera again.
Hopefully this eternally long post has answered your most prudent questions. However, we love questions around here so when you have more do bring them in. I suspect you will want to know about IBL as well as the other advanced lights along the shelf in Bryce 7. But all in due time. I'd just point out that there are better and worse ways of doing certain things such as combining TA and IBL. Do it wrong and the render could be very slow and not vvery accurate. Do it right and the results are amazing the the rendering overall is much much faster. Just ask for advice when the time comes.
Best of luck and see you around. Welcome back!!!!!!!!!!!!!!!!!!!!!
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@Rashad - thanks for dropping by..