Affine transform from appearance embedding

[AdamRashid96]

Changes:

• I added a flag --pipeline.model.use-appearance-embedding that defaults to True
• When set to false the appearance embedding is not passed into the rgb mlp but is instead used to predict a scale and shift for the bottleneck vector. (Zip-Nerf)

Notes:

• Results are variable
• Overall seems to reduce floaters slightly and up the contrast of the scenes
• Sometimes it can cause some extra noise
• It also pushed up the ceiling in the Giannini Hall scene

Comparison: Video

[kerrj]

Right now the behavior of using_appearance embedding is a bit confusing since when it's off, the appearance embedding is still used but it toggles between affine/nonaffine, right? It would be better to have the appearance embedding option expressed as a literal that toggles between 'off', 'affine', and 'mlp' or something

[AdamRashid96]

Yeah I agree the wording is confusing and having two different toggles is unnecessary.