Hi Guys,

First off, I'm a recovering hardcore maya user and want express my love for Houdini! Its revived my love of 3D and honestly believe its the best way to create 3D.

My problem:
My current instancer orients my objects to the poly normal it instanced on (awesome I wanted that) but I'm having trouble working out how to know reorient or blend on a orientation to the Y up while maintaining the randomness I have built in.
My current test render of a forest is attached along with my hip file. The tress are scattering great but look bad since there oriented to the poly normals. One of my colleagues mentioned slerp function but I'm completely lost on how to use it or incorporate it into my point vop.
Thank you to all the contributors on this Forum, I've learnt alot from all of your posts and answers.

slerp() is for quaternions, if you want to build the full orientations for both the y-up and N-up cases, you can use slerp to blend between them using some blend value (0-1).

However, if you want to blend just the up vector from the normal to Y axis, you can use lerp function or mix VOP and normalize the result. Then output the resulting blended vector as your up axis.