Expert Advice Needed for CG Performer Replacement (footage included)

INTRO: I’m a VFX Artist/Filmmaker with a lot of 2d compositing experience working on a short film to bone up on previously unexplored areas to improve my skill.

I’m working on a short film where a full body CG Performer replacement in necessary. It’s a humanoid alien that is basically a slightly taller version of the larger fighter in the clips. I want to make sure I do this right and don’t waste any pointless money or time on efforts that lead to subpar results.

I know I should composite in Nuke, but firstly I don’t have any HDRIs from the day of the shoot to match my lighting. I suppose I could composite together some kind of fake HDRI from the footage? Or maybe there is a better way.

The final alien look will be a 8 foot tall, white, somewhat featureless humanoid alien that slowly shrinks to the performer size and grows human features over the course of the short film. I figure that I can do this look and transitions with a combination of compositing and doing Zbrush customization on the Chris Jones Universal Human with texture/shading in Substance. I don’t really want to have to rig or model a character myself, but I know I may need to combine models and rigs.

Regarding this I figure that I can use something like a blend of keyframed animation to match the performers motion, modified to my Alien Specs combined with the amazing Blendartrack for facial performance capture(I can still film with the actor remotely for this for that), somehow merging the facial tracked performance onto the body model. I know I can model, simulate the aliens somewhat simple outfit(as featured in the film) in Blender with the right addon.

I could really use any expert advice here. I know it’s a big task I’ve set for myself, but the project is a way for me to level up in all the areas I’m weak. I have a lot of experience with compositing in After Effects and I have great understanding of 3d tracking, but character animation and higher end photoreal compositing elude me.
After I finish the character animation and integration I intend to relight and augment the environments in the scenes but that isn’t the priority here. I want to make sure I approach this in a granular way that I can revise as I go if need be. Clean up and making plates won’t be a problem.

Please anyone, take a look at the raw footage to see what I’m working with. It’s entertaining, choreographed by one of the guys who worked on Shang Chi (but this is a totally personal, one man project). I’m sure many can relate to the struggle of wanting to level up and just needing a little guidance to go in the right direction.

fight bits

fight bits 2