Author Topic: Reflection enhancements  (Read 6628 times)

2012-10-18, 17:24:08

superrune

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Some things I would like to see with the reflection in the corona material:

- Option to texture map reflection strength
- Option to disable fresnel for purely reflective materials
- Ability to have strengths over 1.0 and under 0.0
- Reflection exclusion lists

It would also be great to have a separate reflection/refraction-texture, that could be plugged into standard 3ds max materials, or materials from other render-engines.

And for even more flexibility, please consider a reflection/refraction material, that has no surface component - only sending rays away from it. Those are great to use with blend/mix/shellac materials to make complex multi-layered shaders such as car paint, skin etc.

2012-10-18, 17:47:04
Reply #1

Ludvik Koutny

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1, You can always texture reflection strength. If you put any bitmap in the reflection color slot, then it does not override reflection level value, but reflection level value defines maximal value of the map in reflection color slot. So for example if you have reflectivity map in reflection color slot, and reflection level set at 0,6, white pixel on the reflectivity map will have maximum value of 0,6 reflectivity ;)

2, Fresnel is there to keep material physically correct, if you want superreflective material, then set diffuse color to pure black, reflection level to 1, and Fresnel IOR to something like 100 ;)

3, I don't think so, it would break energy conservation therefore it would break pretty much entire renderer ;)

4, That's an ugly fake. Corona is primarily designed to be fast physically plausible renderer with some amount of flexibility, but we are not making another MentalRay. The less fakes - the better performance. If your entire workflow is based on extreme flexibility, then i can only suggest you stick with the renderer you have been using up until now...

If some fake features will be heavily requested, then we will try to add them eventually, but we would also like to ask you to put some effort into changing your mindset and trying to work in a more realistic manner, with as least fakes as possible. You will be rewarded with more realistic results as well as maximal available performance potential of the renderer.

2012-10-18, 18:19:50
Reply #2

superrune

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1+2. Cool, I will play with that.

3+4. I completely understand that for the majority of users (that work within arch and viz), physically correct is the way to go. But if you work with advertisement and vfx, that's not necessarily the thing anymore.

When I do images like this, I prefer going all energy-conserving:
http://www.superrune.com/gallery/images/2010_sozi_group.jpg

But when doing stuff like this, it's almost impossible to be able to find the physically correct values within your deadline:
http://www.superrune.com/gallery/images/2010_trolljegeren_01.jpg

For this job, I had to use different environment maps for different parts of the character. There was different environments affecting the GI and the reflections. I also had to have object that were only seen by the reflections in the eyes etc. There was a ton of cheats on this to be able to make the deadline, and this was a very simple job.

I worked with one of the agencies bidding for the logo of a major beverage brand, and when the art director asked for more intense reflections on one part of the object, it was just the simple matter of cranking them up. It would have killed my deadline to render them separately, take them into photoshop - gain them up etc.

Of course, my existing (now killed off) renderer does this. And there's a lot it doesn't do, that Corona does. That's why I'm always interested in new tech, and Corona looks real interesting. So take it as it is, feature suggestions from an interested artist :)
« Last Edit: 2012-10-18, 18:22:58 by superrune »

2012-10-18, 18:44:37
Reply #3

Ludvik Koutny

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For the character you shown, what you mainly need is a good SSS skin shader, and that is planned :)

For other materials (stones and weed on the troll), if you create them properly, they will always look right, and rest is up to the compositor ;) About reflections, you can always crank them up, and once you hit the value ceiling, you can crank up the IOR ;) Things always can be done correctly in physical manner and yet look good.

That being said, if large amount of people requests something, we will always do our best to make them happy. I usually just suggest other ways to approach the desired result with current state of the renderer, but that does not mean your requests won't be considered ;)

Oh, by the way...  per-material environment override is planned ;) That means materials can have different environment maps for reflections/refractions/illumination, etc... ;) Actually you could see that feature very soon ;)
« Last Edit: 2012-10-18, 18:52:47 by Rawalanche »

2012-10-18, 19:36:52
Reply #4

alieneye

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i totally agree with superrune, you don`t need fakes if you are working with arch or product viz.

but the people who working in post-production will always use fake methods because of their flexibility.
and we are will ask corona developers to implement fakes again and again (turn of GI or for example, or lights include/exclude list  for example)

without this flexibility corona will be another unbiased renderer with same features like octane, maxwell, arion, nox, renderbro, mitsuba etc. 

Don`t make another mental ray, make another arnold  - unbiased renderer with scanline flexibility!

2012-10-18, 19:55:04
Reply #5

superrune

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Sure, a lot is done in comp (I usually comp my own stuff, such as this troll). But there's always clients/ADs/directors saying they want that reflection to POP or that red to be otherworldy. And then there's the issue of integrating with live-action, trying to debug the color of some ground plane through white-balance, coloured lights, lens filters etc. Sometimes an override is all you need to save some hairloss :)

Looking forward to play more with this renderer :)

2012-10-18, 19:58:25
Reply #6

superrune

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Don`t make another mental ray, make another arnold  - unbiased renderer with scanline flexibility!

Quoted for agreement! Arnold is the benchmark at the moment, it has unbiased looks but with renderman'ish flexibility. Its an awesome renderer, but only available for the privileged few (and definitely not for Max...) If they ever release it, I think it will be dominate the render-market.

2012-10-18, 20:04:00
Reply #7

Ondra

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Oh, by the way...  per-material environment override is planned ;) That means materials can have different environment maps for reflections/refractions/illumination, etc... ;) Actually you could see that feature very soon ;)

Its in the alpha3, right...?

about the other fakes: Arnold is unbiased pathtracer. You can't do much else, if you rely heavily on fakes. I can do most of them in Corona, but dont expect for example bidirectional path tracing to work with them.
Rendering is magic.
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2012-10-18, 20:20:33
Reply #8

Ludvik Koutny

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Haha, yeah...  so it will be even sooner than i thought... :D I did not notice it was already implemented. Per-material environment overrides are already there, at the very bottom of texmaps frame ;)