Reflectance Channel issues
Posted: 14 September 2020 02:47 PM   [ Ignore ]  
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Hi. I suspect this has been addressed before, but I’m not seeing a thread. Sorry for such a basic question, but I’m trying to understand the perimeters of creating materials in the Reflectance Channel and not using the Color Channel at all.  I had seen a tutorial on Greyscale Gorilla several years ago about doing this, but when I try it and add animation to the objects, my materials are very grainy and “jumpy” (sorry, can’t think of the right word) when I render them (Standard or Physical renderers).  I see a lot of materials in the C4D content browser that are created this way, but not sure how to use them correctly. I wasn’t sure if it was because this method can ONLY be used with GI and NOT with regular lights/shadows. I would appreciate any understanding someone might share.

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Posted: 14 September 2020 02:57 PM   [ Ignore ]   [ # 1 ]  
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Hi kevschreiber,

Please have a look here, is that grainy?
https://www.amazon.com/clouddrive/share/U2mw6znZ0reSPYJC9OVf9oiQiNXOM7hF8ETfmlqkk7c

I have no idea why the default is for the Roughness to 10%, but that was mostly the problem point here.

If you have a material that is not in the way you like to have it, please put it in a scene file and share it here (zipped)—just the material, no objects, etc., and certainly no 3rd party stuff needed.

I will have a look at it.

Cheers

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Posted: 14 September 2020 04:26 PM   [ Ignore ]   [ # 2 ]  
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Hi Dr. Sassi.

The file you sent looks fine because there is no diffuse-type texture applied in the Reflectance Channel. Where I’m running into the issue is adding materials (textures) into the Reflectance Channels (like a Diffuse layer on the bottom of the stack). In the sample I’m submitting, these are all textures from Kitbash3D.com. They are putting all their textures into the Reflectance Channel and nothing in the Color Channel. But it must work somehow because they have tons of kits built this way and I’ve seen their final renders that don’t have the heavy grain like my sample (I’m also uploading a short render of the materials applied to objects ... especially notice the grain on the smoke stacks / building in the background).

https://gatewaypeople.box.com/s/tg8vnxy56otjxs4y5slb65wzth4fe7b4

Thanks so much.
kev

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Posted: 14 September 2020 05:24 PM   [ Ignore ]   [ # 3 ]  
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Hi kev,

Thanks a lot for the extra work. I got the file!

I will have a look into right away.

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

Photography For C4D Artists: 200 Free Tutorials. Texture, Panorama, HDRI, Camera Projection, etc.
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Posted: 14 September 2020 05:56 PM   [ Ignore ]   [ # 4 ]  
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wow, sir. You are amazing.  Thank you so much.

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Posted: 14 September 2020 06:42 PM   [ Ignore ]   [ # 5 ]  
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Kev,

I went through all materials, and it is quite clear that they are not optimized at all. That is perhaps on purpose. Every scene will get its own aesthetic, as leaving the materials as is has a few disadvantages. I guess there are as many adjustment variations as artists using these. Which is excellent, from my point of view.

When you look at bricks, they usually have a very dull surface, some have some crystal-like sprinkles in it, others have a clear coat over them (I grew up in a construction company, so this is just muscle-memory for me.)
The main idea is, if not wet, they are more or less dull on average. Now, please look at the material. Every single material has a metal layer and a Reflection layer established. Both are set to 100% roughness. Since this seems to be a default, it would be better to put those to zero, in the layer and roughness. Then go from there if at all. Why, because it increases the render-time enormously, and 100% roughness, twice is not what I think will suit most of the given materials.

Again, when it comes to textures (surfacing), there are many ideas all over the place. Fifteen years ago, we went through a lot of effort to convince everyone to render in linear light.
But that works only when the textures are well-calibrated. I have yet to see a texture library that gives you the Color temperature in which they were shot or developed. Nor is any mentioning of the gray-point (card) use.
I could go on for a day about this, or two if I must…

The point is, they are just suggestions or starting points always, nothing that is even remotely physical correct. Hence why everyone will do his/her very own thing with it.

This brings me back to my initial statement; these materials seem to be set as a starting point, not for direct use.

If you like to go with the 100% roughness in two channels, prepare for very long render-time. As the quality must be higher than in the Physical Render.

I would think that the bricks will look OK with the old and more often abandoned Specular Blinn [fake!]. For a decade, we have all trashed this option and evangelized everyone to use reflections only.

When I think how often I get that people render without Motion Blur because it takes so long, I ask myself, is it worth having “Saving Private Ryan” film stutter aesthetic, but an ego pleasing “real” specular highlight?

As usual, it is an artist’s call. I’m the last one who claims that I found the one and only settings. So, please evaluate whatever tips you got with what pushes the mood forward and enables other qualities. BTW, often a lot of motion blur and /or DOF/Bokeh eats a lot of noise.
I’m not sure if I would bake noise reduction into the rendering.

Please check all layers about the roughness value, and if you want to keep it, set the quality in the Physical Render accordingly. Patrick went one time through all parameters of this in a series here on Cineversity.

https://www.cineversity.com/vidplaytut/the_physical_renderer_-_part_1
Currently, sadly not online, fingers crossed it will be back soon.

I hope that helps

All the best


https://help.maxon.net/r23/en-us/Default.htm#html/MMATERIAL-ID_MATERIALGROUP_REFLECTION.html?TocPath=Material Manager|Material Properties / Material Editor|_____9

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 15 September 2020 02:57 AM   [ Ignore ]   [ # 6 ]  
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Wow, Dr. Sassi.

Thank you for such a quick and thorough response! Impressive. I will carefully parse through your suggestions and see what I can figure out.

Gratefully.
kev

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Posted: 15 September 2020 10:01 AM   [ Ignore ]   [ # 7 ]  
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You’re very welcome, Kev, thanks for the reply.

I wrote a lot, as it is not a 0 or 1 answer that can be given.
Over the years, so many things have changed, but sometimes older methods might save a lot of time while providing acceptable results.

In other words, I provided a few thoughts to make the “art’s decisions” a little bit richer (which might vary from artist to artist, of course.)

Before I do a long text, here again, let me say:

Enjoy.

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

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Posted: 15 September 2020 02:28 PM   [ Ignore ]   [ # 8 ]  
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Will do, my friend.  Have a great evening.

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Posted: 15 September 2020 02:38 PM   [ Ignore ]   [ # 9 ]  
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Thanks a lot, Kev, for the kind reply.

I hope you have a great evening as well.

Cheers.

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

Photography For C4D Artists: 200 Free Tutorials. Texture, Panorama, HDRI, Camera Projection, etc.
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