pixal3d_mrp_mlx/pixal3d_mlx/cond.py
m3ultra bd0f3f1941 Proj conditioning: camera back-projection, grid_sample, DINOv3 (12/12 vs upstream)
The pixel-aligned conditioning is the ONLY thing separating this port from the
trellis2_mlx operator already in MODELBEAST — upstream's main branch is the
TRELLIS.2 backbone, so everything else here is TRELLIS.2 with a different head.
This lands that head.

  proj.py  ProjGrid, project_points, bilinear_sample, distance_from_fov — MLX
  dino.py  DINOv3 ViT-L/16 left in torch on MPS (run once per image, outside the
           25-step loop; transformers gives exact parity for free)
  cond.py  encode_image_proj equivalent -> {'global','proj'} + zero uncond

The extractor has no sparse conv, so upstream RUNS on CPU torch here and is a real
oracle. All 12 checks diff against it, not against a transcription:

  bilinear_sample vs grid_sample     max diff 2.4e-07   corr 1.00000000
  project_points pixels/depth/mask   exact
  ProjGrid forward (ss, 16^3)        max diff 1.9e-05   corr 1.00000000
  extractor global tokens            max diff 0.0e+00   corr 1.00000000
  extractor proj features            max diff 4.8e-06   corr 1.00000000

Three details that a plain transcription gets wrong and eyeballing cannot catch:
grid_sample's align_corners=False maps a normalised coord to ((c+1)*size-1)/2, not
(c+1)/2*(size-1) — half a texel, invisible until you compare; padding_mode='border'
clamps the SOURCE INDEX before corners are taken, not the corners after, which
changes the weights on every silhouette edge (tested with deliberately out-of-range
grid coords); and the camera looks down -Z, so a sign slip still yields a plausible
grid that samples the mirror image.

Also corrects a shape assumption from the earlier smoke test: 'global' is CLS + 4
register tokens = [B,5,1024], NOT the 1370 image tokens. The patch tokens go to the
proj branch. That asymmetry IS the architecture.

Note the parameterless final layer_norm in extract_features — not model.norm, which
has weights. Same trap as the ss_flow bug: no checkpoint trace, 200x output error.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-03 13:52:41 +10:00

69 lines
2.9 KiB
Python

"""Image -> conditioning dicts, the MLX side of upstream's `encode_image_proj`.
Produces exactly the two-key contract the DiT blocks expect:
cond = {'global': [B, 1+regs, D], 'proj': [B, R^3, C]}
uncond = zeros of the same shapes (classifier-free guidance negative)
`global` is cross-attended; `proj` is projected and ADDED, one token per voxel. The
token counts differ (5 vs R^3) and that asymmetry IS the architecture — see proj.py.
"""
from __future__ import annotations
from typing import Dict, Tuple
import mlx.core as mx
import numpy as np
from PIL import Image
from .dino import DinoV3Encoder
from .proj import ProjGrid, distance_from_fov
# The four extractor configurations upstream builds in inference.py. Only `ss` is wired
# so far; the other three additionally need the NAF upsampler, which doubles their
# proj_channels to embed_dim*2 by concatenating a high-res branch.
CONFIGS = {
"ss": dict(image_size=512, grid_resolution=16, use_naf_upsample=False),
"shape_512": dict(image_size=512, grid_resolution=32, use_naf_upsample=True, naf_target_size=512),
"shape_1024": dict(image_size=1024, grid_resolution=64, use_naf_upsample=True, naf_target_size=512),
"tex_1024": dict(image_size=1024, grid_resolution=64, use_naf_upsample=True, naf_target_size=1024),
}
def load_image(path: str, image_size: int) -> np.ndarray:
"""Path -> [1,3,S,S] float32 in [0,1], LANCZOS-resized like upstream."""
img = Image.open(path).convert("RGB").resize((image_size, image_size), Image.LANCZOS)
arr = np.asarray(img, dtype=np.float32) / 255.0
return arr.transpose(2, 0, 1)[None]
class ProjConditioner:
"""One extractor stage: DINOv3 + a ProjGrid at that stage's voxel resolution."""
def __init__(self, stage: str = "ss", device: str | None = None):
cfg = CONFIGS[stage]
if cfg.get("use_naf_upsample"):
raise NotImplementedError(
f"stage '{stage}' needs the NAF upsampler (proj_channels = embed_dim*2); "
"only 'ss' is wired so far"
)
self.stage = stage
self.image_size = cfg["image_size"]
self.encoder = DinoV3Encoder(image_size=self.image_size, device=device)
self.proj_grid = ProjGrid(grid_resolution=cfg["grid_resolution"],
image_resolution=self.image_size)
def __call__(self, image_chw01: np.ndarray, camera_angle_x: float,
distance: float | None = None, mesh_scale: float = 1.0
) -> Tuple[Dict[str, mx.array], Dict[str, mx.array]]:
if distance is None:
distance = distance_from_fov(camera_angle_x, mesh_scale, self.image_size)
z_global, z_patch = self.encoder(image_chw01)
z_proj = self.proj_grid(z_patch, camera_angle_x, distance, mesh_scale)
cond = {"global": z_global, "proj": z_proj}
uncond = {"global": mx.zeros_like(z_global), "proj": mx.zeros_like(z_proj)}
return cond, uncond