pytorch3d定义的mesh结构在pytorch3d.structures.meshes源码中可以看到。
首先，meshes数据可能包含多个 mesh结构，每个mesh可能又不同的顶点数和面数。pytorch3d的meshes结构在load obj 或plt文件中的数据后，给出了三种不同的数据格式，分别是：verts_list, verts_packed, verts_padded。
- def verts_list(self): 与输入相同，未处理
- def verts_packed(self): 为方便用于深度学习，pytorch3d有针对mesh结构的batch dimension，为保持每个数据长度一致，它将每个mesh填充找到最多点数的mesh，该点数为max（V_n），并将其它mesh点数填充到max（V_n）
def verts_packed(self):
"""
Get the packed representation of the vertices.
Returns:
tensor of vertices of shape (sum(V_n), 3).
"""
self._compute_packed()
return self._verts_packed
- def verts_padded(self):packed是将点数压缩存储的一种形式，它没有batch dimension，但有额外的信息来存储每个mesh的相应点。
def verts_padded(self):
"""
Get the padded representation of the vertices.
Returns:
tensor of vertices of shape (N, max(V_n), 3).
"""
self._compute_padded()
return self._verts_padded
faces与verts情况类似，可查看链接。
def _compute_padded(self, refresh: bool = False):
"""
Computes the padded version of meshes from verts_list and faces_list.
"""
if not (
refresh or any(v is None for v in [self._verts_padded, self._faces_padded])
):
return
verts_list = self.verts_list()
faces_list = self.faces_list()
assert (
faces_list is not None and verts_list is not None
), "faces_list and verts_list arguments are required"
if self.isempty():
self._faces_padded = torch.zeros(
(self._N, 0, 3), dtype=torch.int64, device=self.device
)
self._verts_padded = torch.zeros(
(self._N, 0, 3), dtype=torch.float32, device=self.device
)
else:
self._faces_padded = struct_utils.list_to_padded(
faces_list, (self._F, 3), pad_value=-1.0, equisized=self.equisized
)
self._verts_padded = struct_utils.list_to_padded(
verts_list, (self._V, 3), pad_value=0.0, equisized=self.equisized
)
# TODO(nikhilar) Improve performance of _compute_packed.
def _compute_packed(self, refresh: bool = False):
"""
Computes the packed version of the meshes from verts_list and faces_list
and sets the values of auxiliary tensors.
Args:
refresh: Set to True to force recomputation of packed representations.
Default: False.
"""
if not (
refresh
or any(
v is None
for v in [
self._verts_packed,
self._verts_packed_to_mesh_idx,
self._mesh_to_verts_packed_first_idx,
self._faces_packed,
self._faces_packed_to_mesh_idx,
self._mesh_to_faces_packed_first_idx,
]
)
):
return
官方文档中的解释
pytorch3d.structures.meshes — PyTorch3D documentationhttps://pytorch3d.readthedocs.io/en/latest/_modules/pytorch3d/structures/meshes.html
