Image Planes(passes)

[csp]

Hello,

I have one question which does my head in. In Houdini 11, Mantra is coming with few default image planes (passes) and it seems that the most of them are not active and some other seems to have misleading titles.

For example the direct_diffuse gives you every lighting information (direct and indirect) including the shadows. At the same time indirect_diffuse gives nothing no matter which light you use (ex. Inderect Light). You can always use Light Export and get each light to a different pass and problem solved but... WHY? I cant let it go and I would love someone to solve this mistery, propably I'm missing something here.

There are other image planes with misleading names, direct_specular and indirect_specular gives nothing, and the specular highlights goes to direct_reflections when the reflections goes to indirect_reflections, which it's not totaly wrong but what's the point of specular passes and why leading industry softwares can't agree to have some standart names for every pass?

cheers

[Macha]

I think some of those passes might only be available if you use PBR rendering. The others will only work if the shader actually exports the appropriate variable. In general it is best if you make your own aov by exporting the variables you need from your shader and then setting them up in the renderer with relevant names.

Apart from those pbr specific passes that come directly from the render engine (?) I think the rest is just for convenience and "hey look, that's how you can use this stuff now go and play"-kind-of-thing

Edited February 1, 2012 by Macha

[symek]

Default passes are the combo with Mantra Surface Model + PBR. They were actually well thought and shaped to the extend of what makes sense here. Unlike some other solutions out there, it's not the only passes to your disposal (as Macha mentioned). It's quick start to make your setup (though afaik it works in 80% of cases)

[csp]

Macha:

I think some of those passes might only be available if you use PBR rendering.

SYmek:

Default passes are the combo with Mantra Surface Model + PBR.

Thank you Macha and SYmek, I never thought the PBR because I did all my passes tests with micorpolygon rendering but now I have two reason to start playing with PBR, the other is that my tutor told me "Mantra PBR is the future, and the type of renderer Industry want our students to have experience of"

Macha:

It's quick start to make your setup

I realized that yesterday and re-construct the Mantra Surface material in order to export whatever pass I was missing and add to extra functionalities like ambient occlusion and id. But I have one last question, using the mantra surface shader how can I get the diffuse without the color? Its the only thing I was unable to achieve. The information is inside the surfaceModel node but it comes out with the base color. I know that I can get that by changing the base color to white and use it in different take, but I like to have all the passes in the same file and avoid recalculations.

cheers

[csp]

I am doing test renders with PBR and I found something odd with the passes. Let's say you have a sphere with the chrome material - default settings -(it happens only with the chrome material), a point light - default setting - and you set an direct_diffuse image plane(pass).

The direct_diffuse gives you what you expect but there is black hole where the specular highlight should be or in that pass shouldn't be. If you disable the specular from the material or from the light, it goes away. Is seems wrong, because if you decide later in compositing not use the specular you have to fix this.

Edited February 1, 2012 by cparliaros