OTOY Forums

Hello Octane Team,

Sometimes, especially when doing interiors, I would like to be able to rise the amount of light which is (diffuse) reflected from a material.
E.g. sometimes I need a certain amount of diffuse reflection from the floor to light up the ceiling enough, but the client demands a dark wood floor...
I think I remember vray has something like this in their "material wrapper" which can be used for any material...

Another use could be to be able to control the amount of color saturation for diffuse reflection, e.g. sometimes I have quite unrealistic looking green colors on my walls resulting from diffuse reflection of grass , i use in the scene...

so basically I would like to have a multiplier for the amount of light which is diffuse reflected and the saturation (color bleed) of the reflected light.

Is there any chance to implement such a think?

best

Andreas

Hi v-cube,
I think you're referring VRayOverrideMtl to avoid color Bleeding effect.
With unbiased render unrealistic tricks engines not so possible.
In real photographic technique you should use reflective panels to bring ceiling light and lighten it, or panels with very diffused light.
In this case you could try a small bit Emission power in ceiling material. It not to light the environment, but just lighten the ceiling.
Regards
Paride

paride4331 wrote:Hi v-cube,
I think you're referring VRayOverrideMtl to avoid color Bleeding effect.
With unbiased render unrealistic tricks engines not so possible.
In real photographic technique you should use reflective panels to bring ceiling light and lighten it, or panels with very diffused light.
In this case you could try a small bit Emission power in ceiling material. It not to light the environment, but just lighten the ceiling.
Regards
Paride

Hello Paride, thank you for the feedback...
yes, I think it was the override material... thank you for your suggestions, I know there are workarounds and I use some of them but I think my suggestion would make our lives much easier...

For example, today I was working on an interior scene, everything was set up perfectly, I arranged the last details and wanted to do the final rendering... then I had a final call from the client "we must use another floor !"( 60% darker!) so there goes my light setup...

Of course there is always the possibility to do such things in Post, but it always creates bit of extra workarounds that tends to make a project more complicated and time consuming, I personally like to be able to do as much in 3D as possible and only do minor adjustments in pp.
Using reflective panels is also sometimes troublesome because they are visible in other perspectives or in reflections, Emitter on the other hand can cast weird shadows ...
it would be so nice to have the ability to give the diffuse reflectance a little material based boost...

best

Andreas

I really would like to read a word from a dev. here ...

Andreas

Hi Andreas,
before being an Octane user, I was Vray and Maxwell user; two very different engines, with different qualities and defects.
Software like Octane and Maxwell do not allow these tricks but this is not a flaw, it depends on about render engine.
GPU render engine programming is very challenging compared to CPU render engine, so features like you ask for, that might seem simple to have, is actually very complex for an unbiased GPU engine.
I think developers will want options like you ask for, but they are very busy with other structural features at this time (see 3.08 SDK and 3.09 SDK) and as you said, override material tool can be solved with post editing.
Regards
Paride

v-cube wrote: so basically I would like to have a multiplier for the amount of light which is diffuse reflected

Not the answer you're asking for, but for your example you could also use several portals above your floor with normals oriented the same direction as your floor: more portal layers you have, more reflected diffuse you get.

Hello Paride, first of all thanks again for the feedback.

with all due respect, I like to disagree here. Like you I also used vray for years, have been beta tester and also worked with maxwell for a few month , I am totally aware of the different approaches of the engines.
But although I cannot be 100 % sure, I really have difficulties to imagine that such thing would be so hard to implement. I am talking about a multiplier for diffuse reflection, so imagine this:

Let's say I have a surface that has a grey of 100, the surface is lit by direct and indirect light, light is hitting the surface, resulting in a certain amount of illumination. Depending on its physical characteristics (mainly its color for diffuse reflection) it will absorb a part of the received light and emit the rest onto other surfaces.
With a "multiplier override" it would be possible to simply increase the amount of each emitted light entity by let's say e.g. 20%, which would be equivalent of an grey color of about 122. so octane would simply "show" the grey 100 but use a grey 122 for the diffuse reflection.

We can argue if this is a worthy thing to add ( IMHO it is... ) but the argument "we can do this in post" is true for 80 % of everything...

I am interested in having a convenient way to edit material looks without changing the lightning situation everytime and as an addition to have a good way of getting more light in problematic scenes, beside that a saturation slider would give me control over unwanted color bleeding.

I see that the devs are probably fixing the last bugs for the next release which is of course a good thing, so i will wait for a few more weeks now and I am curious If this will ever get any attention aterwards...

best regards

Andreas

paride4331 wrote:Hi Andreas,
before being an Octane user, I was Vray and Maxwell user; two very different engines, with different qualities and defects.
Software like Octane and Maxwell do not allow these tricks but this is not a flaw, it depends on about render engine.
GPU render engine programming is very challenging compared to CPU render engine, so features like you ask for, that might seem simple to have, is actually very complex for an unbiased GPU engine.
I think developers will want options like you ask for, but they are very busy with other structural features at this time (see 3.08 SDK and 3.09 SDK) and as you said, override material tool can be solved with post editing.
Regards
Paride

calus wrote:

v-cube wrote: so basically I would like to have a multiplier for the amount of light which is diffuse reflected

Not the answer you're asking for, but for your example you could also use several portals above your floor with normals oriented the same direction as your floor: more portal layers you have, more reflected diffuse you get.

Hello Calus,

Although you are right about this not being exactly what I was searching or hoping for , i find this interesting...

I always thought that portals are used to give the octane engine a kind of guidiance where environmental light will enter a room, to be able to calculate the light solution in a more efficient way.

I did not know that this would act as a kind of booster/ multiplier ...or that multiple portals will add??

Best

Andreas