OTOY Forums

I'm using some arroway textures and I want to know how tweaking the shader
putting the spec in the specular channel but for the roughness using the invert of the specular in this channel ?
I will try with a mix material, putting the spec channel in the mask mix material.
Thanks for your feedback

Hi Rickky,

Are you after an inverter?
There in an invert node under (right click in node graph) -> Add Node -> textures -> mappings -> invert.
Is that what you want?

Cheers
Chris.

The invert doesn't quite work because the values will be way off with white being a roughness value of 1... It's an issue I've found to be incredibly challenging when working with image based roughness maps in octane. I've posted about it before, but now there's more people who can maybe help out.

Roughness works exponentially, and it's extremely strong. By that I mean the difference between 0.0001 and 0.001 roughness is very noticeable, it's quite a large step of blur difference. For the standalone using sliders it works out ok because there's an exponential curve to the slider. For the max plugin is it much harder since there's no exponential curve to the slider(last I checked) so we type it in manually.

It gets worse using an image because I have not found a good way to display black as 0.0005 (or anywhere between 0.001 and 0.0001) using black values from an image map... Say I want white in the image to be 0.001 and black to be 0.0005, and the greys in between range in there. How could I go about it?

What I would wish for within octane is an automatic conversion of the linear values 0-255 to the exponential values of .000001-.1 without requiring more work from the texture artist using mix/multiply/etc. I'd imagine it's just some math since the slider in the standalone already has it built in.

20% black in an image texture should be 20% of the range between the lowest roughness possible(mirror) to the highest possible roughness (blurred goop).

tehfailsafe wrote: 20% black in an image texture should be 20% of the range between the lowest roughness possible(mirror) to the highest possible roughness (blurred goop).

+1

thanks for your feedback. I understand better now why it is so tiedous to tweak spec with bitmap image.
Hoping that the developer put this issue on their todolist and continue tweaking by numbers for now

For now you should put a color correction node after the roughness map, enable the invert checkbox, and you can increase the gamma value and decrease the slider value.

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Roeland