light/shader questions

[jurweer]

Hi guys, congrats on the release! We took the liberty to get licenses and get going straight away

We are porting a maya project to houdini and are running in a couple issue/have some questions:

- there is no temperature color mode on any of the lights in houdini. i am not sure if i missed a post or a workaround in the beta forum or if this is coming still. we use this a lot, so a fix for this would be very welcome!

- the standard values for the shadow bias are 0,02 in maya, in houdini its set to 0,002. is there a specific reason for this? I dont see any difference in when comparing them.

- there is a scale parameter missing on lights. in maya we sometime create ellipsoid light from sphere lights. i found the only work around is to add a tranform node inside the light. Although this does work, it is not a very clear solution as we would always have to dive in a light, or make stickynotes etc. A scale parameter on the Transform section of lights would help a lot.

- on the VRayMTL BRDF ( maybe others) there is an Amount slider missing on the Diffuse/Relfect/Refraction parameters. When converting our projects to VfH, we would need to build in this slider as a color multiplied with a float operation on each of these attributes, on all shaders, as the Maya VRay Next shaders have that included. Would be nice to have in VfH too!

- BlendMTL seems to be missing the Base Mat input. Is this the first input when creating BRDF inputs?

Thanks in advance!

We are on Build 3551ba6 from the 26th of July 18:37 with Hou 17.5.293

[chakarov]

Hello jurweer

- there is no temperature color mode on any of the lights in houdini. i am not sure if i missed a post or a workaround in the beta forum or if this is coming still. we use this a lot, so a fix for this would be very welcome!

Looks like we miss this one, as a workaround you can use V-Ray TexTemperature and load it as a texture for the light.

- the standard values for the shadow bias are 0,02 in maya, in houdini its set to 0,002. is there a specific reason for this? I dont see any difference in when comparing them.

I'm not really sure why this value is chosen, but to get some visible difference you should set a value above 0.1

- there is a scale parameter missing on lights. in maya we sometime create ellipsoid light from sphere lights. i found the only work around is to add a tranform node inside the light. Although this does work, it is not a very clear solution as we would always have to dive in a light, or make stickynotes etc. A scale parameter on the Transform section of lights would help a lot.

I really couldn't get scaled light to be rendered "right" neighter in Houdini or in Maya. Can you send me such a scene?

- on the VRayMTL BRDF ( maybe others) there is an Amount slider missing on the Diffuse/Relfect/Refraction parameters. When converting our projects to VfH, we would need to build in this slider as a color multiplied with a float operation on each of these attributes, on all shaders, as the Maya VRay Next shaders have that included. Would be nice to have in VfH too!

I've reported this one. As a workaround I can suggest to use ColorOperations with output "result_a" connected to diffuse input of the V-Ray Material, and connect a userFloat to "mult_a". Actually this is what V-Ray in Maya does under the hood.

- BlendMTL seems to be missing the Base Mat input. Is this the first input when creating BRDF inputs?

Yes, it's the first input "brdf_1" of the BRDFLayered /Blend material/

[Gosho.Genchev]

Regarding the Shadow Bias on the lights - it used to be the same as in Maya but the scale in Houdini is meters by default, and centimeters in Maya which caused issues with fine details. There was a request a while back to reduce this. 0.002 seemed to work well so we stuck with that. If you stumble upon any trouble, please ping us.

Cheers!

[jurweer]

thanks for the fast reply and reporting some of the things!

will the light temperature be fixed or is the textemperature the houdini way to go? i am asking, cos there are a lot of shaders to convert and i dont want to risk compatibility in future updates...

[chakarov]

Yes, temperature color mode for lights is planned, should be soon, but I can't give you an estimated date. Anyway there is no reason for compatibility problems, even if you has TexTemperature set to your light.

[ArthurD]

The color picker in Houdini has Kelvin temperatures. Just FYI

[jurweer]

The color picker in Houdini has Kelvin temperatures. Just FYI

thanks for that! i wasnt aware!

[Gosho.Genchev]

Huh, the more you learn. I wasn't aware of this either.

jurweer , is that an option for you guys or should we look into adding the Color Mode drop-down similar to Maya ?

[jurweer]

i guess it has become a habit using the color mode like maya

the kelvin mode in the color picker seems great to me!