Germany, Berlin
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Re: Chromium / Stainless / Metal in General
Background: Shininess in reality is a blurred reflection, similar to looking at a lamp through slightly frosted glass.
Illustration: If a point light source shines to the tip of a dirty shoe, you see hardly any highlight - the incoming light is widely scattered. Then you wax the shoe but don't polish it: a wide, not too bright highlight appears - more light is kept around the reflection angle. Shoe polished: highlight intensifies and shrinks - even narrower scattering, but no clear reflection yet! Chrome plated shoe : the light source gets clearly mirrored (albeit shrunk due to the curvature).
With simple renderers, this is mathematically modelled by a so-called specular exponent. Every curve in the diagram shows for a given exponent Ns (see legend) how much light is scattered how far away from the reflection angle. Ns = 0: perfectly diffuse reflection Ns = 1: cosine function Ns = 128: nominal maximum written by SH3D Ns = 1000: recommended maximum in *.mtl files (SH3D accepts them) Ns = ∞: directional reflection
The steeper the slope, the shinier the surface. But obviously, with any finite Ns, some light will always deviate more or less from the reflection angle.
Test with SunFlow as well as yafaray Render the scene with different shininess values of the large box, and with the large box set to mirror. Compare the difference images of different shiny renders to the perfectly matte (shininess = 0) render
Expectation: mirrored object is blurred to a degree inverse to shininess. I.e., infinite shininess = sharp; finite shininess = blurred; zero shininess = completely dissolved.
Observation Changing the shininess in SH3D has two consequences. 1. The result image is always a weighted blend of diffuse and clear reflection. The Shininess controls the blending weight, nothing else. Like if you overlay an image through a clear glass pane with one of a sheet of paper. No scattering takes place. 2. SH3D writes the shininess to the Ns value upon export of *.obj/*.mtl files.
Conclusion
SH3D approximates shininess by weighted blending of clear reflection into the diffuse image. For low specularities this is an acceptable compromise in favour of software maintainability and processing load. SH3D limits it to 128 which is sensible.
All over SH3D, no scattering is implemented, neither with transmission.
Varnish or metallic roughness demand a high specular exponent. Therefore they can not be modelled straight forward but only resembled or made up by post-processing the render result(s).
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Cheers - Joe //
Russia
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Re: Chromium / Stainless / Metal in General
I'm in a great mood in the morning. I'm really looking forward to your comments. I have two tips for you. 1 this is SH3D. 2. This is SH3D and nothing else)). No Photoshop, no Gimp, no Blender. There are no all these double shells and transparent textures, there is ONE light source, the Sun. I want to stall a little)). I think we are on the verge of a big discovery that needs to be studied.
Germany, Berlin
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Re: Chromium / Stainless / Metal in General
Stop thrilling! It's tearing me apart! Did you manage to make Ns effective? New Version of yafaray? Other Renderer? Magic group name prefix? Some Config setting nobody knows? Or even a code patch? What's the solution?
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Cheers - Joe //
Russia
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Re: Chromium / Stainless / Metal in General
I apologize for the delay in responding. I'll tell you everything now, of course. But first, I will explain my doubts and worries about my "discovery".. I have mixed feelings. Imagine that I drove for a very long time to another city to visit a small art gallery. There are a lot of world masterpieces of painting in it, I have long dreamed of seeing with my own eyes. And here I am in front of the door, but no one opens it for me. I knock, I ring, they don't open. In desperation, I walk around the beautiful old museum building and suddenly see a slightly ajar window.. there is no one around, and I decide to climb in through this window. Here they are, MASTERPIECES, right in front of me. Rembrandt, Van Gogh, Kandinsky, Vrubel.. A fantastic feeling of happiness from what he saw. But the door is closed! And there is no one in the museum. What should I do about it and how much time do I have before the police arrive? I really want all my friends to see these masterpieces, but how can I tell them about this window? After all, you need to go through the door!! And there is no key to the door. Okay, I'll tell you about the window. Maybe you can figure out what to do with it next. I don't know right now. Of course, I put it figuratively about the police, there is nothing criminal here.
but not everything is so rosy.. The effect of reflections of objects in the surface is manifested only when assigning a COLOR to the surface. If texture is needed, then the effect is very weak. I assigned a dark gray color and 128 gloss in MTL for boxes and perforated modules and this unpolished steel turned out. Of course, I set the highest quality level, the fourth and Yafaray. The rendering time of 2000x2000 pixels is 1 hour. At the third quality level with the same verbal rendering settings of 8 minutes, the picture quality is grainy, but acceptable. With shaking hands, I uploaded my complicated scene to test my discovery on it. And a complete fiasco.. very grainy surfaces, the time is monstrous.. I do not know what to do with this WINDOW now, I do not know how to use these render settings for real work. Two plates in the form of steel is certainly good. But what to do with a normal, but still closed front door??.. I am waiting for your opinions.. in an hour I will upload a picture with texture instead of color for steel surfaces. It seems to be starting to work out.. We need your participation in the experiments too. Or do you just tell me what to do next?
Russia
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Re: Chromium / Stainless / Metal in General
I have assigned a texture from the SH3D library to steel surfaces at a scale of 1%. This makes it possible to obtain a rough surface without visible mesh repetitions, with absolutely any textures according to the pattern. The main thing is the general shade of color, gray-blue, for example, for steel. You can probably use seamless JPG images with a larger scale. We need to experiment.
I see that by assigning texture instead of color, reflections have changed!!! They have become double, I will not rush to conclusions, I still need to study carefully. But in general, the color of the reflections has become dimmer.
Germany, Berlin
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Re: Chromium / Stainless / Metal in General
First of all, in an attempt to play with the new discovery, I failed to find the yafaray render properties dialogue you posted. Does it take a hack to reveal it? Probably, It's once more just too late at night for me to spot it.
Second, I'm curious about the behaviour when the texture has an alpha, as this is how I (have to) make my myriad of holes.
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Cheers - Joe //
Russia
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Re: Chromium / Stainless / Metal in General
advanced photo and video rendering settings can be downloaded on the plugins page, it is at the bottom, select the newest one. By Enko Nyito I've dealt with this mode. In the setting of the fourth level, there is a parameter (highlighted in red) that allows you to add grain only for special glossy surfaces, where moire reflections will be. This parameter greatly reduces the processing time, and as a bonus gives a rough texture for steel. The rest will be matte without grain. While I haven't had time to test on difficult scenes, I have some problems with my computer. I didn't have time to load a more complex scene, where there are mirrored objects and the render work is visible in surfaces with color (parquet at the bottom) and textures (everything else). It is more or less possible to apply, up to a certain limit of the complexity of the scene. I'll attach the pictures later