Chaos Corona for Cinema 4D > [C4D] General Discussion
physical mat | reflection intensity question
Stefan-L:
well, i am not totally sure, but that's another thing.
i do not mean slight imperfections, but the pure intensity itself often needs to be reduced.
like there are glasses in reality with greatly reduced reflections but still an refraction like glass (around 1.4-1.6), probably with some special coatings that absorb reflection, etc and our archviz customers very very often demand less reflections materials, like glass,
so at least for artistic reasons it might be very good to be able to mimic these materials which do exist in reality, or to react easy on customer wishes without "destroying" the rest of the material (like in setting the ior way too low, or need to change the roughness, which the end customer probably also not wishes).
so i not want to set the glass ior to like 1.1 (which will give me a wrong refection look) but be able to reduce the reflection intensity by 50% as example.
or another example i just work on which is more about work flow: a floor with different tiles(differences in material of the tiles), that i want to have slightly different reflection intensities, i can set variations in all material features only not in reflection. this makes me feel limited. i needed to make several separate materials and assign them manually. this is a bad work flow and costs time. this would lead to the need for a value+texture slot as it is in refraction too.
i believe such features like the physical should make our live easier, almost all other phymat features have a "value+ texture " setting, so i hope this could be added to the reflection too. it is not more or less non-physcial than the volume or refraction setting i believe.
aler:
--- Quote from: Stefan-L on 2022-01-21, 18:24:04 ---i believe such features like the physical should make our live easier, almost all other physmat features have a "value + texture " setting, so i hope this could be added to the reflection too. it is not more or less non-physcial than the volume or refraction setting i believe.
--- End quote ---
+1
Stefan-L:
here is one example of real world materials that seem not possible to create with the new physical material unless it gets some kind of "dim reflection" feature:
https://uk.saint-gobain-building-glass.com/en-gb/sgg-vision-lite
Staint Gobain is one main glass producer worldwide, the glass is widely used in architecture. one big feature it has is low reflection glass. see the table on that page how extreme the reflection is reduced while retaining transmission(and glass like IOR refraction like around 1.5).
lass materials are today one essential thing for architecture, but the above materials are only one example, but in architecture are several real word mats, like facade panels that have intentionally reduced reflections.
while for opaque materials it might be a way to reduce the ior to dim reflections,
for transmissive materials that need to keep a correct IOR (glass = 1.5), one atm cannot reduce the ior while setting the correct physical real word reflection.
so i hope for a intensity or value % slot as we have it in other material features already in the new physical material.
i only try to improve the phymat to be able to really be capable to cover most of the real world materials, so we can fully switch to the new, otherwise great(love it!), new physical material :-)
aler:
Dear developers, it is strange that you still did not answer in this thread.
Then I will support Stefan again and give an example.
A simple rough metal (for example Aluminium), but its specular is overexposed. It's Clamping, loss of color, and that's bad. And inside the material I do not find options to adjust the specular the way I need it (pic.1).
But I would like the metal to have a soft specular (pic.2). Here in VFB in Tone Mapping I have raised Highlight Compress to 20. However this is not the best way, because everything else has also become pale.
Of course you can do it through Multi-Pass: assign a separate mask for metal, and then from 1 render make 2 saves - the first is normal, the second with a weakening of the overexposed, and then work in Photoshop (pic.3). This is a working method, but it involves additional actions.
Therefore, it would be more convenient if for Specular/Reflection were provided for convenience additional adjustments (Level, Color, Mix Strength...) (pic.4).
burnin:
Hard to conclude anything... as it appears to me, simply darkening base color could do... Care to provide scene?
-------------------------------
For the Saint-Gobain glass you can study/check & see how it's done w/ Indigo renderer since original producer has provided their official materials (w/ measured tabulated data) HERE.
Notes:
--- Quote ---Official measured glass materials from Saint-Gobain
Post by saint-gobain-glass ยป 24 Aug 2011 09:28
Dear Indigo users,
Please find in the material database several new materials, officially measured, provided and supported by Saint-Gobain Glass, a glass making company.
These materials are not licensed under the creative commons license, but under a specific copyright license included in the material description and in the igm code. To summarize, the materials are free of use for any commercial and non-commercial project, and sets no restriction on the use of the generated images. Free distribution of unmodified material files associated with brand and products names is allowed. Main restriction is on modified versions of the materials which cannot be distributed.
Best Regards,
Etienne
--- End quote ---
Finally/TL;DR,
IME, lower IOR is defined, I think this way, because Indigo abides to the same physical principal & CG model(?):on a single material reflective = refractive IOR, which can't be separated, so when user wants to make this "duality" physically accurate, it has to model it. And here's where higher FP accuracy & volume priorities come to play.
So, for those scientific & engineering minded, wanting to know more on predictive rendering for these kinds of complex materials, it's worth to tickle the brain in the Ocean ( ;) involved in creation of glass & engine).
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