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# Hunyuan 3D is licensed under the TENCENT HUNYUAN NON-COMMERCIAL LICENSE AGREEMENT
# except for the third-party components listed below.
# Hunyuan 3D does not impose any additional limitations beyond what is outlined
# in the repsective licenses of these third-party components.
# Users must comply with all terms and conditions of original licenses of these third-party
# components and must ensure that the usage of the third party components adheres to
# all relevant laws and regulations.
# For avoidance of doubts, Hunyuan 3D means the large language models and
# their software and algorithms, including trained model weights, parameters (including
# optimizer states), machine-learning model code, inference-enabling code, training-enabling code,
# fine-tuning enabling code and other elements of the foregoing made publicly available
# by Tencent in accordance with TENCENT HUNYUAN COMMUNITY LICENSE AGREEMENT.
from typing import Union, Tuple, List
import numpy as np
import torch
from skimage import measure
class Latent2MeshOutput:
def __init__(self, mesh_v=None, mesh_f=None):
self.mesh_v = mesh_v
self.mesh_f = mesh_f
def center_vertices(vertices):
"""Translate the vertices so that bounding box is centered at zero."""
vert_min = vertices.min(dim=0)[0]
vert_max = vertices.max(dim=0)[0]
vert_center = 0.5 * (vert_min + vert_max)
return vertices - vert_center
class SurfaceExtractor:
def _compute_box_stat(self, bounds: Union[Tuple[float], List[float], float], octree_resolution: int):
"""
Compute grid size, bounding box minimum coordinates, and bounding box size based on input
bounds and resolution.
Args:
bounds (Union[Tuple[float], List[float], float]): Bounding box coordinates or a single
float representing half side length.
If float, bounds are assumed symmetric around zero in all axes.
Expected format if list/tuple: [xmin, ymin, zmin, xmax, ymax, zmax].
octree_resolution (int): Resolution of the octree grid.
Returns:
grid_size (List[int]): Grid size along each axis (x, y, z), each equal to octree_resolution + 1.
bbox_min (np.ndarray): Minimum coordinates of the bounding box (xmin, ymin, zmin).
bbox_size (np.ndarray): Size of the bounding box along each axis (xmax - xmin, etc.).
"""
if isinstance(bounds, float):
bounds = [-bounds, -bounds, -bounds, bounds, bounds, bounds]
bbox_min, bbox_max = np.array(bounds[0:3]), np.array(bounds[3:6])
bbox_size = bbox_max - bbox_min
grid_size = [int(octree_resolution) + 1, int(octree_resolution) + 1, int(octree_resolution) + 1]
return grid_size, bbox_min, bbox_size
def run(self, *args, **kwargs):
"""
Abstract method to extract surface mesh from grid logits.
This method should be implemented by subclasses.
Raises:
NotImplementedError: Always, since this is an abstract method.
"""
return NotImplementedError
def __call__(self, grid_logits, **kwargs):
"""
Process a batch of grid logits to extract surface meshes.
Args:
grid_logits (torch.Tensor): Batch of grid logits with shape (batch_size, ...).
**kwargs: Additional keyword arguments passed to the `run` method.
Returns:
List[Optional[Latent2MeshOutput]]: List of mesh outputs for each grid in the batch.
If extraction fails for a grid, None is appended at that position.
"""
outputs = []
for i in range(grid_logits.shape[0]):
try:
vertices, faces = self.run(grid_logits[i], **kwargs)
vertices = vertices.astype(np.float32)
faces = np.ascontiguousarray(faces)
outputs.append(Latent2MeshOutput(mesh_v=vertices, mesh_f=faces))
except Exception:
import traceback
traceback.print_exc()
outputs.append(None)
return outputs
class MCSurfaceExtractor(SurfaceExtractor):
def run(self, grid_logit, *, mc_level, bounds, octree_resolution, **kwargs):
"""
Extract surface mesh using the Marching Cubes algorithm.
Args:
grid_logit (torch.Tensor): 3D grid logits tensor representing the scalar field.
mc_level (float): The level (iso-value) at which to extract the surface.
bounds (Union[Tuple[float], List[float], float]): Bounding box coordinates or half side length.
octree_resolution (int): Resolution of the octree grid.
**kwargs: Additional keyword arguments (ignored).
Returns:
Tuple[np.ndarray, np.ndarray]: Tuple containing:
- vertices (np.ndarray): Extracted mesh vertices, scaled and translated to bounding
box coordinates.
- faces (np.ndarray): Extracted mesh faces (triangles).
"""
vertices, faces, normals, _ = measure.marching_cubes(grid_logit.cpu().numpy(),
mc_level,
method="lewiner")
grid_size, bbox_min, bbox_size = self._compute_box_stat(bounds, octree_resolution)
vertices = vertices / grid_size * bbox_size + bbox_min
return vertices, faces
class DMCSurfaceExtractor(SurfaceExtractor):
def run(self, grid_logit, *, octree_resolution, **kwargs):
"""
Extract surface mesh using Differentiable Marching Cubes (DMC) algorithm.
Args:
grid_logit (torch.Tensor): 3D grid logits tensor representing the scalar field.
octree_resolution (int): Resolution of the octree grid.
**kwargs: Additional keyword arguments (ignored).
Returns:
Tuple[np.ndarray, np.ndarray]: Tuple containing:
- vertices (np.ndarray): Extracted mesh vertices, centered and converted to numpy.
- faces (np.ndarray): Extracted mesh faces (triangles), with reversed vertex order.
Raises:
ImportError: If the 'diso' package is not installed.
"""
device = grid_logit.device
if not hasattr(self, 'dmc'):
try:
from diso import DiffDMC
self.dmc = DiffDMC(dtype=torch.float32).to(device)
except:
raise ImportError("Please install diso via `pip install diso`, or set mc_algo to 'mc'")
sdf = -grid_logit / octree_resolution
sdf = sdf.to(torch.float32).contiguous()
verts, faces = self.dmc(sdf, deform=None, return_quads=False, normalize=True)
verts = center_vertices(verts)
vertices = verts.detach().cpu().numpy()
faces = faces.detach().cpu().numpy()[:, ::-1]
return vertices, faces
SurfaceExtractors = {
'mc': MCSurfaceExtractor,
'dmc': DMCSurfaceExtractor,
}