I’m not sure how original these kind of papers should be but here are some ideas of stuff that’s not part of Panda3D (yet):
Indirect lighting in a deferred shading pipeline.
Shadow mapping for multiple point lights.
Shadow volumes with penumbra wedges (GPU generated?).
Hardware (shader based) skeletal animation.
Post-process effect that increase scene realism (exposure control, eye adaptation, glare, lens flare, chromatic aberration, depth of field, motion blur).
Image based ambient lighting (using parallax-corrected cubemaps).
Order independent transparency (for deferred shading?).