I am working on a piece that has a wood floor... a chair with shiny metal legs sits in the scene... the polished metal looks like the wood... I noticed in C4D and 3DS Max when the metal is metal it shines like 'metal' regardless of what it is reflecting... Is this a function of reducing the reflection and increasing the refraction (as drawbridgep suggested)? A function of Radiosity and the lack thereof? Thoughts? -Susan

I wasn't aware that non transparent objects had refraction... Refraction is the resulting change in angle when light enters a new median, water, glass, etc. If light is not transmitted through the object, it has negligeable refraction.

Excellent lesson in refraction... I tried the reducing / increasing thing... but it didn't work... looking for answers... -Susan

huh? susan, i think you're asking 3 questions here.. first of all, you can make metal shine like metal through the way the material behaves (bump maps, reflection maps, etc). second, reflection variables do influence shine. increasing the quality of the render might also give you better results. third, in terms of radiosity, bryce doesn't do it, it can only fake it, and even in that sense, radiosity is not how objects shine as much as the light that they reflect unto others (and not the quality of the shine itself) drac

How about a screen capture to see exactly what's going on?

Also the ambience and diffuse channel affect how much of the objects color shows in relation to it's reflection. If those are zeroed out, then reflection will drive most of the appearance (but color can still be used to tint things with use of metallacity.) Check Bryce's defaults of white metal, blue metal, and brushed silver & pewter to get an idea of how that works.

Thank you pauljs75 for this response and also for all your wonderful models... I think I used your 'skateboard' in an image of mine... I will definitely test this out... -Susan

I don't know why, but I've noticed that some textures (even some of the Bryce5 presets) have refraction set higher than 100, even though they have 0 transparency. When I change the refraction to 0, it seems to have no effect on the appearance of the texture in rendering (although it does speed it up, indicating perhaps that the higher refraction setting was doing something, I just don't know what).

I found that too! I guess that the people who make them just don't know that refraction only works on 'transparent' materials... as 'Ornlu' suggests... -Susan

ewww.... will be following this. The only book I've had explaining Bryce to me is the User manual. Now.. English is my second language, - and I thought I mastered it pretty well, - but I never got those pages... and the DTE left me (or would that be I left the DTE)... totally confused! Ack. I have come to understand that what Ornlu says is at least partially true. If it ain't transparent, it hasn't got any refraction. Refraction is (if I've finally gotten this part of DTE), the angle the light beams break through a transparent material. Now... Mirrors; they're not transparent... but they do cast lightbeams BACK... that would be reflection... Right? But.. what if the mirror is damp; those lightbeams would refract through the waterdrops on the mirror, and be reflected in a different angle than they were destined for... Did I understand this correctly? :)

Refraction still might do something with how light falls off of an object when the angles approach that tangent with the line of sight, even when an object is not transparent. But I've yet to test that hypothesis. Perhaps someone with a stronger 'puter render a few spheres under varying conditions and settings to test it. But then again it just might be an unfounded thought.

I've found that with a metal texture, if it's TOO reflective, it can achieve a similar look if you decrease the reflection, and increase the Diffusion. If the reflection is at 100, try decreasing it to 75, and increasing diffusion from 0 to 25. You can change each of these attributes as you see fit.

Yup, something HAS to be transparent to have any refraction. And, Bryce cannot have it's mirrors reflect light off itself. (I realize some of you would argue with me until doomsday about that, but lets just assume we are NOT faking radiosity with TA and a 256 RPP render) ;o) Why most of the non-transparent Bryce prestes come with the refraction set, is beyond me, and it is one of my pet peeves about Bryce presets, as it instantly confuses people. I swear I will make this change in Bryce 5.5, 6.0, lol. Anyway...as most have said; Have your reflection and diffusion add up to 100 (50-50, 75-25, etc) Add a small, fine bump to your reflective legs. That should do it. Beacuse a straight mirror material will reflect the floor nearly perfectly, and will cause the effect you are seeing. (given the right camera angle) AgentSmith

Attached Link: http://www.vray.info/entry.asp?entryID=77

EVERYTHING has an index of refraction. Refraction is simply the bending of light as it travels from one location into another of different density. Every object and voluminous mass, if it's transparent or not, bends light in a certain way and to a certain degree, depending on it's density. Even AIR. This is known as Index Of Refraction (IOR)

See the link attached for the exact IOR of various real materials. I'm not aware that Bryce supports true physical IOR values for it's materials. Modern renderers in programs like Cinema4D and 3dsMax have support for these physical properties on a material level, which adds to the realism of the way lights in a scene react with objects and increases realism in the renders. Many 3D programs today support IOR values, but some do not. Even Poser 5 has a refraction node where one can adjust the IOR value of a material to immitate that material's real life interaction with light. Message edited on: 09/01/2004 01:42

"bending of light as it travels" Travels or passes. (which is one of the two words always used in the definitin of refraction) Both which mean the subject has some sort of transparency... Metal is not transperent, not even a little bit, at least a chrome table leg is not. So, no refraction is possible. Nor, is REAL radiosity in Bryce, so, there ya go. Sure, the air between two non-transparent objects can have refractive properties. (but I'm not sure if you would see any difference in Byce if you did this) (scene enveloping cube with refraction?) But, to apply a refraction setting to a non-transparent material is misleading to those needing to understand the DTE, imo. (I guess that's my real point/concern) No, it doesn't change/hurt anything, but it does cause members to ask whether or not the refraction level on their metal material is correct, lol... AS

Attached Link: http://www.du.edu/~jcalvert/optics/plane.htm

You're correct in the fact that it really wouldn't make a difference in renders with Bryce, since there's no radiosity or physics calculations taking place. Just increasing the refraction of a material isn't going to change it's overall appearance in a render if it's not transparent - unless there are photometric lights in the scene being calculated.

"Travels or passes. (which is one of the two words always used in the definitin of refraction)"

The correct terminology would be "passes". My typo. But it still remains that everything absorbs light to some degree in real life, even metal. If that has an affect on your renders is mere speculation, because as mentioned, there's no physics calculations taking place in Bryce anyway. Even if there were, the difference in the way light affected the scene based on IOR values on non-transparent objects would be negligible if there were no photometric calculations taking place, I would think. Message edited on: 09/01/2004 02:08

"Bryce cannot have it's mirrors reflect light off itself." I was really disapointed when I learned that Bryce would not do that and I keep thinking it's a trick that would be nice to figure out, as I'm not really satisfied faking it; but once found it would lengthen render times even more. Bryce rendering is already way slow and if it weren't for being able to set rendering to the background (just minimize Bryce while rendering) while I'm doing other things like checking out the net,sleeping or away I'd be at wits end with it. So the compromise between render time and image quality is always in play. Every once and a while though I get the idea in that in Bryce the light angles aren't always calculated right; I noticed this once with sunlight actually getting the visable lightray effect as described by Peter Sharpe but with the sun - about 30 or more degrees from where one might expect (a picture showing this is archived somewhere on this forum on some thread I started some while ago - something about faking trees using spikes) . . . so there might be some bug or feature . . . anyrate I keep trying new things with light . . . but then in all likelyhood someone would have found mirror lights by now if such existed. As far as refraction goes, Bryce appears to try to emulate the real world closely. Although a completely opaque surface won't show or use refraction(at least not in the real world and in my observations not in Bryce either) , making things only slightly transparent might allow Bryce to begin to work with it. It might be a worthy experment to see at what point (percent transparency) an object begins to show differences in the way it looks due to refraction in Bryce. - TJ BTW: Refraction is only noticed at the interface(surface) between two objects with noticably different indices of refraction such as (approximately): air/glass (1:1.6 ) air/water (1:1.3) glass/water (1.3:1.6) but it has to work by light actually going through the object. It is a confusing subject but once learned not easily forgotten.

Sidenote - everything maxxxmodelz is saying IS true, just not entirely in the Bryce world. ;o( (but we can always fake it baby!) You are the guys Bryce coders need to talk to when they start on Super Bryce (6.0)...;o) AS

"everything maxxxmodelz is saying IS true"

not everything.

"Everything absorbs light to some degree, therefor has an index of refraction"

Again refraction is only noticed at the interface of the materials - the fact that materials absorb light is irrelevent unless that light again reaches the interface (surface) which ain't necessicarally(sp?) so.

• TJ

Message edited on: 09/01/2004 02:51

"Again refraction is only noticed at the interface of the materials - the fact that materials absorb light is irrelevent unless that light again reaches the interface (surface) which ain't nessisarily so."

This is true, not all materials transmit light. However, the important issue is absorbtion, or the amount of photons that are actually absorbed by a material. Again, Bryce doesn't actually calculate photon transmission of lights, so it's meaningless to Bryce renders, but it could play a factor in renderers that use physically correct lighting and photon mapping. Message edited on: 09/01/2004 03:05

Hey, guys, I'm not trying to add any oil to the fire, lol, but I just did continuous animation (only refraction changing from 0 to 300) of single golden sphere, with some bumps on it, and it shows some changes in render, expecially around specularity area, subtle, but still a change, so Bryce, it seems, calculates something different each time, also specular area is little bit bigger at refraction 300 then the one on refraction 0 ...Go figure :) P.S. Animation was viewed as BMP animation (no compression) in Jasc Animation Shop 2 and renders were BMP images...this effect is relatively small, and I'm afraid that any video compression would make it much less visible, lol !!!

not for the visable effects of refaction it isn't. Perhaps in some theoretical point of observation within the naterial at some subatomic level but not as it is observed from outside the object looking at the surface. What we might consider for working in Bryce is multible interfaces, tranlucent or transparent paints, varnishes waxes etc and the fact that truely 100 percent opaque surfaces are not as common as we might at first think for example a leaf, a hair, some plastics and all skin all have some degree of transparency/translucence. What is absorbed into the material is lost as far as the refraction we see at the surface goes - what light is absorbed affects color and radiosity but not refraction. - TJ

Kemal, Don't confuse me with the facts! Thanks I'll check it out. care to post a screenshot of your settings?

Setting was, since I discarded Bryce file: Refraction 300 Bump 4 ( "sandy" bump, scale 500, parametric) Diffusion 75 Reflection 25 Animation 50 frames -> refraction 0 to 300

"not for the visable effects of refaction it isn't.
Perhaps in some theoretical point of observation within the naterial at some subatomic level but not as it is observed from outside the object looking at the surface."

But in the case of copper and gold for instance (both metals), light IS emitted back to the surface after absorbtion in order for us to see it's color, correct? In which case, wouldn't refraction would play a role in how those materials render?

LOL... someone remind me I need to brush up on my physics when debating with bikermouse. ;-) Message edited on: 09/01/2004 04:05

maxmodelz, Reflection of what is not absorbed is what we see. I think you might be confusing reflection with refraction. Kemel, I animate so infrequently in Bryce I forgot: You have to fix the sky or "it moves". More than likely what you're seeing is sun and cloud movement. - TJ

"Reflection of what is not absorbed is what we see. I think you might be confusing reflection with refraction." LOL... Yep, I realized what I said two seconds after submitting it. It's late, and we're debating physics. ;-)

Yep, I know, hehe ! @ bikermouse: That's negative, sir, my sun and sky/clouds did not move ( cloud parameters were on 0, turbulance and speed) and sun was linked to the view ! :) I just tried simple multiple render (not animation) and rendered 10 single tiff images with different refraction and animated those myself in AnimationShop, and still I can see a change !!! :) Dunno, maybe I'm just sleepy, lol, it's 5:30 AM here !!! :)

Kemal, maybe you unlocked the "Pro Render" secret formula! LOL. (whoops, was I not supposed to mention that name? My bad). ;-)

maxxxmodelz, You think this one's bad. You should have heard the conversation I had with Michio Kaku when we were kids at the coy pond in the Japanese Tea Garden in Golden Gate Park while our respective parents were having "tea". I remember asking whether I could call him Michael and he said "My name is Michio!" He seemed unduly concerned about the coy and how they saw the world for some reason . . . I told him a trick about how to hypnotise the fish so they could be caught and when he denied that he was trying to catch the fish but rather that he thought they saw the world 2 dimensionally that led to a theroretical conversation that was way above my nine year old head . . . I suspect he was a little older; he bacame the physicist he said he wanted to be although I never did become an archeologist. . . . Kemel, I tried the gold thing before my last post and the only thing I noticed was the changes one would expect with sky movement . . . hmmm . . .I'll try again tommorrow, see if I can stop the sun and clouds for sure and see what I get. You might be on to something - If so I suspect bump mapping might be involved but we'll see. - TJ

Interesting talk, with reference to Mirrors and refraction what no one has pointed out so far is that a mirror is made of glass (which refracts ) with a silver layer on the back, so to model a mirror truly, you would need two objects in bryce, a glass and a metal. Having pointed that out, this often true of chrome table/chair legs which are often lacquered or plastic coated, what you need to do get very accurate is to use the shellac fake that AS posted here a while ago. (more advanced renderers support shellac style materials on one object, but bryce isn't there yet...)

Gog, this is true, however they are talking pure metals here. @kemal try with a white background, no sun and a single omni light instead. This way you are insured that there are no variables other than the refraction. I have tried this in the past and could see no difference between refraction indexes on solid objects with no transparency. As I stated earlier, bryce refraction functions solely on transparent objects. Bryce does not support reflecting light or true caustics because it lacks any significant photon simulation engine. Reflecting light and caustics are created by reflective and refractive properties. Let's start with caustics. When a light goes through an object it is bent due to the refractive index, we've been over this. This is only incident on the surface of the object unless the refraction changes throughout the object itself. While a beam of light is inside the object and otuside the object it remains straight. Let's take a sphere for example. The light enters at say 45 degrees.. it is then bent (for example's sake) 20 more degrees. (this is why a straw looks like it's bent when you put it in a glass of water) anyway, now the beam of light exits the sphere at a new angle due to the incident with both the front and the back face of the sphere. The light has not passed straight through but has instead been redirected, in the case of a sphere, all light entering is slightly bent towards the center upon exit, This is why the caustics effect of a transparent sphere with relatively high refraction is a bright dot. When bouncing off of the surface of a pool light is gathered in a different effect. But anyway, all caustics is is a non uniform distribution of light brought about by refractive surfaces. Light bouncing off a mirror is like a simplified version of the above. Unfortunately bryce only supports direct illumination (disregarding ta, which really has nothing to do with illumination at all, but with the proximity of ambient surfaces) This effect would again be predicted with photons. Think of photons as light particles. they bounce off of reflective surfaces and stop on opaque surfaces, tracing a line behind them. Now take a million of these and throw them out from a light.. this is what photon simulation does. The photons then would bounce off of the reflective surface at the opposite interior angle to the incident beam. once they have reached the opaque surface that stops them they illuminate it. Bryce lacks such an engine, thus anything like reflecting light off of mirrors or creating caustics (without faking it) is indeed impossible.

As far as 'everything absorbs light' at some level goes.. thats' true but what does that have to do with refraction? It would have negligeable effect as the light would never leave the other side of an opaque object. And if the opaque object were thin enough to allow light to pass through it the refraction would become negligeable as the surface volume is not great enough to have any effect. What I think you're refering to is sub surface scattering, which is very much impossible in bryce and certainly not noticeable on metalic objects even in the real world.

"with a white background" kemel, I tried with a black background, made two renders one wach at 0 and 300 closed my eyes for the time it took to change from one render to the other in my viewer and saw no differrence whatsoever. Sorry I couldn't duplicate what you saw even though I tried to be as objective as I could be. - TJ

Hmmm. Made a render of metal with no refraction on the mat. Made the same render with a refraction of 300 on the metal. I can't visually see any difference, and my (thumbsplus)program says that both renders have the same exact number of color pixels in each, so I would say, with normal settings, there's no difference. In Bryce, with basic settings, anyway. :o

Would be cool though, if someone could "invent" some sort of settings in Bryce that you could see a change in refraction in non-transparent objects.

"What I think you're refering to is sub surface scattering, which is very much impossible in bryce and certainly not noticeable on metalic objects even in the real world." Yeah, re-reading what was discussed last night again today (after a decent 7 hours of sleep), I see there were a couple things I definitely had mixed up there. Warning: That's what happens when you try debating someone about render theory/physics after having been modeling for the past 20 hours straight. LOL! But at least the conversations in this thread inspired some people to try different things with refraction to see for themselves, which is always good. ;-)

Ornlu wrote: "(disregarding ta, which really has nothing to do with illumination at all, but with the proximity of ambient surfaces)" Are you speaking from firm knowledge of the operation of True Ambience in the Bryce render engine, or from assumption? How does your description explain my observations in this thread; http://www.renderosity.com/messages.ez?Form.ShowMessage=1445452 Why should "the proximity of ambient surfaces" be affected by objects that have no ambient setting (the transparent and reflective items)? How do such objects bend and bounce "the proximity of ambient surfaces"? I don't show it in those pics, but if the refractive index of the transparent sphere is changed, the shape of the light pool behind it changes too. If I change the transparent colour of the sphere, the colour of the light pool changes too. How does this equate to "the proximity of ambient surfaces"? The proximity of the ambient surfaces in those pics is constant. The supposedly non-existent illumination is altered by the reflective, refractive and transmission properties of non-ambient objects.

Ok, let me explain. The true ambience portion of the bryce renderer functions as follows. Any object with an ambient value on the surface is immediately calculated. At any location where this object is reflected it is also calculated. Therefore, if the light is seen in a mirror it will have an 'ambient' value where the reflection is in the mirror. 'sphere' of influence is created at however many RPP with a certain falloff depending on the level of ambience in the material. This sphere of influence then reacts with other objects in its proximity, projecting the ambient levels onto that object. If this sphere of influence increases the ambient level of the secondary object, then that object in turn generates its own spheres of invluence (greater where it is effected by the other spheres) thus generating the caustics effect. You will notice that the same effect is generated with a white opaque surface.. The only two values taken into account by the true ambience render is the value for ambience and the color . Now, you mentioned that there is a 'caustics' effect on the transparent sphere. This is caused by the same phenomenon, look at the sphere, you will see that the basic 'refractions' in bryce cause the incident reflection/refraction of your white planeto be projected on both sides of the sphere.. one at the original incident reflection, and one on the other sides incident reflection+refraction. These 'reflections' shown on the sphere are treated as very ambient 'textures' by the true ambience renderer, thus they generate their own 'spheres' of ambient influence in these two incident locations (no volume refractions, only the front and the back of the sphere) which were then interpreted by you to be caustics. Hope this helps. Try doing that transparent sphere render with no reflection value and note the change in appearance.

after 2 months of trying to get the Pro-Render settings,checking all the bryce threads on TA and anything related,I have to say that refraction does do something.But NOT in normal renders(at least to non-transparent objects).It does however seem to give diff effects with "VolumetricWorld" settings on,and or TA.I have to support PJF on his observations.I have recreated all of the experiments PJF did in the thread he just mentioned.And some things he hasnt said.For example, I made a sphere with a metal mat that had refraction at 100,and another at 300.The sphere at 300 reflected MORE TA light than the other(note: it will not do this if the sky is set up wrong).Which leads me to another obsevation, if your sky is set up in a certain manner, it can and will entirely change the scene,and the way mats look.

Also one more thing, the light in your scene would probably act very similarly with a plain plane without reflection as it does with the mirror.

oh, but I do not agree on the TA effect being caustics or "light photon" like.its not,just a trick with TA as Ornlu suggests.

Hmmm... Looking at some of the posts I like where one idea was going. Allowing light to parially penetrate objects before bouncing back would be awesome. Then refraction would play a role. This would eliminate having to duplicate objects to get that clearcoat or a proper mirror backing effect. This would would really be a useful property with imported objects, as scaling something up doesn't always keep things spaced and results in poke through. I suppose other renderers achieve this by somehow layering materials and being able to use more than one shader. Hopefully these features will be seen implemented at some level whenever the er-Bryce comes out.

"Ok, let me explain."

I'd love it if you did, Ornlu but, or course, you didn't.

Sadly, you ignored my first question, which is important. Let me ask more directly. Are you relaying information that you have gained by interacting with Bryce 'personnel' who know; or are you drawing your own conclusions?

Now, let's go back to the beginning. The Bryce5 manual states:

True Ambience - Computes the ambient light
for a surface using the color and intensity of
nearby surfaces, resulting in color blending
from one surface to another.

This statement has been quoted several times (including by no less than AgentSmith) to pooh-pooh various suggestions about the nature of True Ambience. There's some laughing, and a "that's all it is" response, as if the manual statement was the full and final word of God on the matter.

Examine the manual statement for the first premium effect listed:

Soft Shadows - Softens the edges of the shadows.

Whoopee. Does that actually say anything about how shadow softening happens? If there were some debate over the process of how Bryce soft shadows occur, would anyone have any respect for someone who said, "it's just the softening of the edges of shadows, lol"?
The manual statement about True Ambience is equally shallow and vague, yet appears to carry sufficient weight to deter further thought for some.

Why is this relevant? Because what you said, Ornlu, is no more an explanation than the Bryce manual. You offer no detail of the processes involved. I don't mean to sound harsh, but I don't think you have any more idea of the specifics of how True Ambience works than I do, or anyone else outside the Bryce coding fraternity does. And the details and specifics of how it works are fundamental to these discussions. They would resolve all the notions of 'radiosity', 'caustics' or whatever.

To deal with what you said (not in order):
"The only two values taken into account by the true ambience render is the value for ambience and the color ."

This is not true. For example, in post 6 of the thread I linked to, the only ambient materials are on the ground plane and the purple cylinder. If ambience and colour are the only values taken into account, why is the scene (apart from the bright white diffuse surface) visible at all?

"Any object with an ambient value on the surface is immediately calculated."
Er, what does this mean? Calculated? Immediately?

"At any location where this object is reflected it is also calculated. Therefore, if the light is seen in a mirror it will have an 'ambient' value where the reflection is in the mirror."
This has important implications, so I hope you're not just making it up as you go along.
From what perspective is this reflected ambience 'seen'? Does the render engine interpret the reflection from the 'point of view' of the reflective object, or from the 'point of view' of the camera? What process does the render engine use to 'see' the ambient surface reflected in the mirror, and to treat the reflection as another ambient surface?

"'sphere' of influence is created at however many RPP..."
This is interesting. You've brought rays into the discussion. In what way do rays operate in True Ambience?

"You will notice that the same effect is generated with a white opaque surface.."
No, I notice that a white, opaque surface generates an entirely different effect. Look at posts 3 and 5 in the link. The big sphere has an opaque material the same as the ground plane. No 'caustics' seen as via the reflective spheres there. Setting the big sphere material to maximum white, maximum ambience has no effect with regard to the appearance of 'caustics' on the floor. An opaque surface does not deliver the 'caustic' effect.

"Now, you mentioned that there is a 'caustics' effect on the transparent sphere. This is caused by the same phenomenon, look at the sphere, you will see that the basic 'refractions' in bryce cause the incident reflection/refraction of your white planeto be projected on both sides of the sphere."
Do you see the enormity of what you are saying here? You are suggesting that the render engine can take account of an internal reflection caused by refraction, and then use that internal reflection to create a 'sphere of influence' for another effect. That's pretty major, even in the absence of an explanation of how it actually occurs. If you read my thread carefully, you will note that the scene in post 6 has reflections disabled. This makes your explanation even more amazing.

"...the light in your scene would probably act very similarly with a plain plane without reflection as it does with the mirror."
No. The light in my scene most certainly acts entirely dissimilarly under such conditions.

As an 'explanation', you've offered a mix of mistakes and generalisations. It's certainly a leap from the "proximity of ambient surfaces", but looks very much like a leap in the dark. You've offered nothing in the way of a process by which these generalised notions might occur. In the absence of such a description, you might as well say that draculaz's robot "immediately" wonders through the scene and paints the ambient 'spheres of influence' in watercolour.

But you did mention rays. And that mention, inadvertent as I suspect it was, is pleasing to me. Since Bryce is a raytrace renderer, it is entirely reasonable to assume that the process of True Ambience operates via 'rays', much as every other effect in a Bryce render is facilitated. And if True Ambience operates via rays, I regard my ideas about it being 'illumination' having virtual optical properties as being as valid as anyone else's ideas about it being nothing more than (magic?) 'color blending'.

Only a detailed, 'official' explanation will settle it.

hmmmm....can we ask DAZ about the renderer? I dont see why it would be a secret, as the program is old.

Of course. AS