Hi. I have an atan2 expression which is taking x,y point positions from a file sop of rendered geometry and I'm trying to bring the rz value into Chops. Oddly enough though, when I use the Geometry Chop I get 2 values: rx and ry with a 0 value for rz. In Sop level that rz is populated with rotational values but the rx and ry are zeroed out.

It is evident by this question that I don't quite understand atan2 expressions and how they interplay between sop level and bringing that data into chops.

Can someone explain how to get my rz values to show up as a single channel in chops? Thanks in advance.

any example?
it can show much more than you describe as we don't really know if you are using expressions to populate rz parm, or creating r attribute using atan2 expression in Point SOP or atan2 in VEX not that it maters, it's not the problem of atan2 function
if you have rz value in sops, CHOPs will read it correctly
Geometry CHOP reads attribute values so if your r or rz is an attribute, it should be fine
if it's an parameter, you should use Fetch CHOP (and possibly set animation range manually in case you are driving that parm with expression)
you can even compute your angle using atan2 in CHOPs directly using either Expression CHOP, VOP CHOP or Function CHOP

so if you post simple example, you can get fast and direct answer

Thanks tamte. I did figure it out in the meantime by using a Fetch chop which I tried to do initially but incorrectly. This time I used Fetch by posting my SOP rz values to OP level inside of a null object different than the one where I got the file sop to read a geometry render. (At first when I tried to use Fetch on SOP channels it didn't work, but I was probably doing something else wrong). Now the tricky part is trying to interpret the rz data that I have into something meaningful which will manipulate other data that I have. I can't really post a file since it's for an exclusive project concept that I'm working on, but if I have further general questions I will post them to the appropriate forum section. Thanks for reading and responding. :-)