World/Point Position Pass in vray...

[evanerichards]

I am looking to create a World Position Pass in vray. I have taken an extra texture node and connected it to a sampler info node as shown in the picture below.

So far so good. However, when I render it out (I rendered it out as a 32bit floating point image) it doesn't seem to look right. Please see the render below.

Now I'm new at working with WPP so maybe I have the wrong idea, but that doesn't look right does it? Shouldn't it slowly fall off across a surface instead of having a sudden dropoff like that (see the tail)? The very bottom of the feet sort of look good, but again that drops off at the ankles.
It seems like it is rendering in eyespace rather than worldspace (see image below for reference)

Am I doing something wrong?

Thanks in advance!

[vlado]

This looks about right. The effect very much depends on the scale of your scene (obivously). The "reference" you are looking at is probably a square that is 1 unit wide and placed at the center of the coordinate system. I very much doubt that this is true for your actual scene

You can use the multiplier of the ExtraTex element to scale the coordinates if you want, but this shouldn't be necessary.

Best regards,
Vlado

[Morbid Angel]

point position cannot be looked at as a visual image. What you have there looks correct. More over, you need to render with "allow shader negative color" option on in full 32 bit color space, otherwise the ppw will get clamped.

[evanerichards]

Ohhh!!! Excellent bit of information there! Thanks! Where would one find the "allow shader negative color" option? I don't believe I've seen that before. Is that a shader setting or a vray setting?

The only reason I thought you would be able to tell it looked right is because of the example I posted below where everything is a very gradual gradient that looks correct. But as Vlado pointed out, that is probably contained within a single unit of the coordinate system.

Regardless, I have learned some new things today!

[Morbid Angel]

in vray tab in render globals under misc i believe

[evanerichards]

There it is! You sir are a gentleman and a scholar!