Bump

[Gruender]

Good morning everybody.

Thx for your great developement.
I figured out that the bump amount (perventage) produces the same result in IR, no matter what value you put in, even at 0% it produces the same result.

Further more I have a question about the bump.
As I am used to shade in vray, I ask myself what that percentage value stands for. For example the default value is 10%, but 10% from what, one meter or centimeter or ...?
Would be good to know that for better shader understanding.

Many thx in advance!

Cheers...

[houska]

The issue with the bump not updating sholud be fixed in the latest dailies.

As for the strength, it's a bit complicated. The percentage is just a relative value, which scales the perturbation that would normally result from performing the bump mapping calculation. Perturbation just offsets the surface normal in some direction by a given amount. As an example, if the normal points straight up and the bump mapping perturbation is 1, the resulting angle is 45 degrees. By increasing the strength to 200%, you'll get a perturbation of 2, which would result in an angle of atan(2/1) ~= 63 degrees. 300% will be 72 degrees, etc...

But then again, you don't know the amount of the perturbation to begin with, without knowing the exact algorithm that calculates the bump mapping perturbation. So right now, I'd suggest just trying it out and use the amount, which feels right. We might think of adding some units later ...

[Gruender]

Thx for you answer!

It doesn't sound handy. I really would prefer a value, maybe the scene units or something like that.

[Rhodesy]

I would also put a request in for a visual unit of measure. I assume its a case of visually doing some calibration to see the effect at different percentages and then factoring that down to a common scale. It makes it easier with less testing by the user if it came pre-calibrated.

[houska]

I would also put a request in for a visual unit of measure. I assume its a case of visually doing some calibration to see the effect at different percentages and then factoring that down to a common scale. It makes it easier with less testing by the user if it came pre-calibrated.

Actually the calibration would have to be done in the software, because different UVW scaling would result in different perceived "depth" of the effect with the same percetnage values, so it's not that simple. But it's a common and meaningful request, so I'm pretty sure we'll do it at some point.

[Gruender]

Just to clearify...

Does the bump with a real world measure work differently compared to the percentage method or is there just a value that makes it easier for users to setup?

Many thx in advance.

[houska]

Does the bump with a real world measure work differently compared to the percentage method or is there just a value that makes it easier for users to setup?

It's pretty much the same. But as I wrote in my previous post, the conversion value would have to be different for each usage of the material, so we cannot just hard-code a multiplier, but we have to dynamically calculate it in the Corona for C4D plugin.

[Gruender]

Ok, thx a lot!