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Help with Emissive shader in Max

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Message 1 of 11
fvitaleC3GHJ
1478 Views, 10 Replies

Help with Emissive shader in Max

I've a few problem with the emissive shader in Max 2018

- Object with emissive shader is casting a shadow from another light in my scene, I've unchecked "cast shadows" under object properties but it's still casting a shadow.

- No way to exclude objects from a light in Arnold??? This is hard to fathom. I've been excluding objects from lights for 20+ years ???

- How can I control the amount of light an emissive shader emits? It seems that upping the number under Emission does the trick but it's really noisy, can I adjust the samples?

- In trying to have no emission of light but still full luminosity on my object, I've reduced the Indirect Diffuse under Basic Parameters to 0 but I'm still seeing light being cast.

As a side note I'm not understanding why Arnold has been brought in as the default render engine for Max and Maya... to this 25 year vet it feel like a step back 30 years. I've been using it now for a few months and feel that I have a passable understanding of it's features and am feeling that it lacks some of the most basic functionality that has been around forever. I was doing things in the 90's that I can't do now - it's quite absurd to be honest. My main career tool is now completely broken. It's very frustrating.

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10 REPLIES 10
Message 2 of 11
fvitaleC3GHJ
in reply to: fvitaleC3GHJ

Another question... is it possible to apply volume to a single light? It seems that volume is only avaiable globably, if this is the case it's seriously limited.

Message 3 of 11
fvitaleC3GHJ
in reply to: fvitaleC3GHJ

For those wondering... I did figure it out, you need to set the Vol contribution for all lights you dont want to have volume to 0... makes sense.

Message 4 of 11

Use a arnold properties on the object, use light group to exclude lights.
You cannot adjust samples for a shader/material, use a meshlight instead.
Use a arnold properties on the object, disable diffuse reflections to not illuminate on other objects from the emission.
You can still use mental ray/scanline, but arnold is way better in render quality.

Message 5 of 11
lee_griggs
in reply to: fvitaleC3GHJ

> How can I control the amount of light an emissive shader emits? It seems that upping the number under Emission does the trick but it's really noisy, can I adjust the samples?

Increase the number of Diffuse samples.

>- In trying to have no emission of light but still full luminosity on my object, I've reduced the Indirect Diffuse under Basic Parameters to 0 but I'm still seeing light being cast.

Did you reduce Indirect Diffuse for the shaders on which it is cast?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 6 of 11
lee_griggs
in reply to: fvitaleC3GHJ

>I was doing things in the 90's that I can't do now - it's quite absurd to be honest.

Can you give an example?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 7 of 11

Object with emissive shader is casting a shadow from another light in my scene, I've unchecked "cast shadows" under object properties but it's still casting a shadow.

If I add an Arnold Properties modifier to an object, and clear the Casts Shadows check box, then that object no longer casts shadows.

I don't know how to reproduce your problem, so can you upload a simple example?



// Stephen Blair
// Arnold Renderer Support
Message 8 of 11
fvitaleC3GHJ
in reply to: fvitaleC3GHJ

Thank you @Michiel Van Gasse but where do I access "Arnold Properties" and "light group" and "diffuse reflections" ? Clearly Arnold has great depth, unfortunately the documentation does not... it assumes the reader already knows the software and leaves one digging endlessly for answers. Also I appreciate your take on the quality of Arnold as a renderer... but I've had a very different experience. I've been creating photo real works for a couple decades using Mental Ray, it give one a great deal more control and much clearer language. I want to learn Arnold but it is proving very difficult. I spend 15 hours trying to achieve a look that I can accomplish with greater accuracy and predictability in two hours with MR. I mean, we cant even preview reflectivity in the material editor, working blind is no fun at all. Mograph seems to have a failry complete tutorial set for a fair price, I'm going to give it a try. http://mographplus.com/product/comprehensive-introduction-to-arnold-for-3ds-max/

Thank you @Lee Griggs the hot link was helpful and I was able to better understand this pipeline and effect. I did not "reduce Indirect Diffuse for the shaders on which it is cast" Is that how it works? That seems crazy... what if you have 100's of effected objects? Seems like a very sloppy way to achieve desired results. To see examples of my work have a look at my site www.33north.net most of it is MR and Max, some is Cinema and some goes waaaay back to the Strata days. It really is frustrating that things I was doing 20 years ago are more challenging now - to me this makes no sense at all. I've taught CGI at multiple schools, I know this industry like the back of my hand and the new tools are just not as easy to use or predictable as the old tools.

Thank you @Stephen Blair I did not know how to get to this... how is one to know that is modifier based without stumbling across it? Thank you!

I appreciate all the input, seem this is a very responsive forum...

Frank Vitale

Message 9 of 11

https://docs.arnoldrenderer.com/x/vYJsAg

You can access the Arnold Properties modifier like other 3ds Max modifiers.

3060-arnold-properties-modifer.jpg

3061-arnold-properties-modifier2.jpg



// Stephen Blair
// Arnold Renderer Support
Message 10 of 11

In trying to have no emission of light but still full luminosity on my object, I've reduced the Indirect Diffuse under Basic Parameters to 0 but I'm still seeing light being cast.

If I understand correctly, I second what @Michiel Van Gasse suggested:

Use a arnold properties modifier on the object, disable diffuse reflections to not illuminate on other objects from the emission.

And maybe disable specular reflections too.

Here's a torus over a grid. The torus has a Standard Surface shader and Emission = 1.0

On the torus, I disabled "visible in diffuse reflections", so now we have just the spec (so if I turn off "visible in specular reflections" too, then the grid won't get any lighting from the emissive torus).

3062-emissive-object.jpg



// Stephen Blair
// Arnold Renderer Support
Message 11 of 11

Why you do not integrate Light/Shadows Include/Exclude directly into the Light setup, using the modifier for this is extremely inconvenient, I have not seen any render in 3ds max, so that this function would be implemented as ugly as you have. Arnold is an amazingly powerful and flexible renderer, completely awfully integrated in 3ds max

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