# Noise SOP specify dimension

I can’t tell the noise SOP to only apply noise to specific dimensions, such as Y. Do doubt there’s a lengthy work around possible but I’d like to request the ability to stipulate this within the SOP. Thanks.

The thing is, the 'workaround’is simple:
The noise SOP applies noise along the normals. So, to apply noise in the Y direction, we can just use a point SOP to make all normals point directly in the Y direction.
So take your geometry, go into a point SOP, activate add normals and put all values to 0 but Y to 1. Feed that into your noise.
After that, recomputing the normals makes sense anyway, so use a facet SOP to recompute the new normals. (or use the attribute SOP for the same thing)
Hope that helps!

I should have been more specific, I am talking about the point position, not the normals. As far as I can tell I can’t get the noise sop to only deform in one direction. Does that make sense?

As hrtlacek says, make all the normals point in the direction you want to deform.

For point position, noise is generated and multiplied with the point normal, and then add to the position data. If the points do not have a normal, the normal is computed by the Noise SOP. E.g., if you put down a grid SOP, the default generated normal is (0,0,1), and you’ll notice that a noise SOP will deform in the z direction only. So if you have geometry you want to deform all in Y, the easiest thing to do is to put down a Point SOP, turn on Add Normal and put down your direction of deformation.

noise deforms along the normals

change normals to Y
and try the noise SOP

thanks for the tip selina !

Thanks heaps you guys.
FWIW this isn’t mentioned in the documentation.

I’ve added a short explanation of how each attribute is deformed. Thanks for pointing this out.