What is faster to evaluate, blendpose chop or `chf` function?

[abvfx]

I guess the title is self explanatory but on the topic im never sure what executes faster in general like chops/vop/sops/expressions etc.

I tried looking for a few guidelines but haven't found them. Most people assume expressions are slow to calculate, but i have heard the same thing from Maya users. It is a correct assumption?

In my opinion a chf curve just seems quicker in terms of a SDK-type of setup than using a blendpose chop with imports and export nodes.

[edward]

The BlendPose CHOP is *definitely* slower. It's designed to do multi-dimensional interpolation (aka scattered interpolation) in ways that it would be nearly impossible to do with expressions alone.

[abvfx]

I dont know why i never seen this response. 

 

This is what i thought but was never sure. I was only going to be using it for 1D interpolation but i still think it isnt faster enough, plus i have to deal with samples. 

[anim]

you need to take into account the difference between expressions and CHOPs

so even though many times you would simply use chf() expression, it's might not be the best option if you have a lot of the channels that need to be remapped and output to different objects

or most notable difference is caching that you get for free from CHOPs

 

so expression that evaluates every frame will cause you scene to slow down much quicker than precomputed CHOPs for the whole range and the more time you play the bigger the overall difference as the chops don't need to recompute, just directly output the value, but expressions are still live and need to be computed

on then other hand the realtime manipulation may feel faster for expressions even if CHOPs run in timeslice mode (it may differ by case though)

 

for your needs you should compare chf() to Lookup CHOP or Warp CHOP as they do both can remap one value according to lookup table as chf() does

and in my test, playback is faster with CHOPs even with only one channel driven by expr/CHOPs

 

just a few things to think about

[abvfx]

Cheers Tomas, i never considered the Lookup Chop. Worked perfectly. It will take some scripting to scale it up. Having multiple poses utilizing bones from other poses all wiring into separate Lookup that are fed into a math chop. I wonder if there is a way of utilizing the pose library to create poses and dumping them into a channel chop. More testing i guess. Thanks again.

 

 

edit:// You dont by any chance know of a faster way of calculating blendshapes? I have used the blendshape SOP but even with an editSOP network it leaves a lot to be desired. I created a SOP VOP that is able to do the same (along with point masking to split shapes up for various zones) but again it leaves a lot to be desired in terms of speed. 

Edited December 21, 2013 by ab3d