How to make CG sit in live-action: lighting, shadows, reflections, AO

[SofiaZR]

I'm a junior VFX artist working on integrating CG elements into live-action plates, and my biggest challenge is making the lighting and shadows look believable, especially for objects that are supposed to interact with real environments. My renders often feel like they're floating on top of the footage rather than being part of it. For experienced compositors, what are the most critical techniques beyond basic color matching for achieving photorealistic integration, particularly when dealing with complex reflections and ambient occlusion?

[Benjamin92]

Shadow catcher is your friend. Put a flat shadow-catcher plane under the CG object on the live plate and bake in a soft contact shadow. Match the lighting direction with the plate, and feed ambient cues from an HDRI or plate-probe so the CG picks up the environment’s bounce. A quick test: render a grayscale shadow pass and composite it to verify depth and contact with the ground plane.

[NatalieSP]

Lighting beyond color: build a three-pass shade A) diffuse, B) specular, C) ambient occlusion. For reflections, sample the plate with environment captures or a blurred reflection map derived from the plate if you can’t shoot a full environment. In comp, use a light wrap and slight color bleed to fuse edges and ensure the CG doesn’t look like it’s floating.

[Ryan.J]

Here’s a practical workflow I use on features: 1) track the plate and estimate the main light direction/color from plate highlights; 2) render with a shadow catcher and separate AO pass to anchor depth; 3) render diffuse, specular, and a reflection pass using HDRI or plate-based reflections; 4) combine in comp with a shadow/matte for the plate, add subtle GI bounce via a light wrap; 5) apply subtle motion blur and depth cues to match plate’s camera; 6) grade for final cohesion. Common pitfalls: missing contact shadows, mismatched depth, and reflections that don’t follow the plate’s lighting.

[Daniel_R]

Don’t neglect edge integration: enable a bit of light wrap around the CG edge so the silhouette blends with the plate, and ensure the plate’s ambient light influences the CG via an environment light or baked bounce. For complex reflections, favor a dedicated reflection pass and a separate ambient occlusion pass so you can tweak bounce without washing out highlights. If you’re on a heavy scene, consider a proxy GI pass or irradiance cache to keep renders efficient while still selling depth.

[Zoey14]

What software are you using (Nuke, Houdini, Blender, etc.) and is this a static shot or a moving plate? Are you dealing with metal, skin, or something with strong speculars? I can tailor a checklist (passes, node setups, and a quick test scene) to your pipeline to speed up iterations.