You can use the Arnold_Point AOV to create a world position pass (an AOV is the Arnold equivalent of a render channel). Here’s the Arnold_Point render channel in the render region:
A world position pass (aka a position map), is an image where each pixel’s R, G, B colour values represent the x, y, z coordinates of the corresponding vertex, in 3D world space.
If you loaded the rendered position map into the FxTree, or Composite, you can see that the RGB values correspond to the XYZ position coordinates:
FxTree:
Composite:
eX-SI 
Cant seem to find that in my render channel drop dpwn? Any tips?
Hi Greg
Do you see the other Arnold AOVs in the list? (If not, run the SITOA_CreateRenderChannels command)
What version of SItoA do you have?
Thanks
2.5ish until my project ships….. I dont see the big list like you are showing, but a rather truncated version. I will try running the comand after my render stops.
Thats the ticket! Thanks
is there a way to get a world y postion pass?this seems to be screen space?