VrayDirt bias effect acting... weird?

[pailhead]

I tried to set up a test to illustrate my problem, but now im even more confused. Basically i want to use the bias function to pull the dirt down towards the ground. But its giving me weird results. Right now, #3 looks good, but im confused by #2.

As you can see #4 has a large bias value (10) and is introducing color black. (BTW youre looking at a vraydiffuse channel, so where does black appear from?). #3 works fine with the bias value of 1, but #2 is producing errors and you can obviously read the segments.


Should i use bias values larger than 1?

What is wrong with #4?

Is there something wrong with #2 (why are you able to read the segments, while #3 has such a smooth transition)?

I want to be able to control this bias by pulling it as much as possible in the Z axis, so i thought, the larger the value, the larger the ratio is between Z and Z:y, but while it works good with walls, whenever i get an arch, i get errors.

[vlado]

It seems kind of normal; it was mostly designed for bias values smaller than 1.0. I have to try and reproduce this here though so that I can see what happens exactly.

Best regards,
Vlado

[dlparisi]

It seems kind of normal; it was mostly designed for bias values smaller than 1.0. I have to try and reproduce this here though so that I can see what happens exactly.

FYI - the example page (http://www.spot3d.com/vray/help/150S...s_vraydirt.htm) shows bias values of 100, kind of misleading.

[vlado]

Yep, I know... like I said I have to look into it more carefully.

Best regards,
Vlado

[pailhead]

Any news on this?

[pailhead]

Vlado do you want the scene?

[vlado]

Well, it's pretty easy to reproduce... but it will be helpful, yes.

Best regards,
Vlado

[pailhead]

Unfortunately i cant find it. Were you able to reproduce?

[CA Portugal]

Try a negative value like -5

[pailhead]

Why?


(1234567)

[CA Portugal]

Not 100% sure, but negative bias values in vray dirt makes the dirt grow from the bottom direction up. I think that can work in your example.

[pailhead]

I definitely want it to work like this, but it seems like it's bugged.

[pailhead]

Here you go, a simple scene that recreates the problem.

http://rapidshare.com/files/426249998/chaosdirt.max

It seems that distribution is causing the black spot to appear. But in my original example, the distributino helps me get rid of the segments in the 3rd sample.

[pailhead]

Is there a chance that anything can be done on this?

[vlado]

Don't know, the file is deleted. Would be best to send it to vray@chaosgroup.com or to me at vlado@chaosgroup.com

Best regards,
Vlado