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Point clouds to volumes
Summary:
Conversion from point clouds to volumes
```
Benchmark Avg Time(μs) Peak Time(μs) Iterations
--------------------------------------------------------------------------------
ADD_POINTS_TO_VOLUMES_10_trilinear_[25, 25, 25]_1000 43219 44067 12
ADD_POINTS_TO_VOLUMES_10_trilinear_[25, 25, 25]_10000 43274 45313 12
ADD_POINTS_TO_VOLUMES_10_trilinear_[25, 25, 25]_100000 46281 47100 11
ADD_POINTS_TO_VOLUMES_10_trilinear_[101, 111, 121]_1000 51224 51912 10
ADD_POINTS_TO_VOLUMES_10_trilinear_[101, 111, 121]_10000 52092 54487 10
ADD_POINTS_TO_VOLUMES_10_trilinear_[101, 111, 121]_100000 59262 60514 9
ADD_POINTS_TO_VOLUMES_10_nearest_[25, 25, 25]_1000 15998 17237 32
ADD_POINTS_TO_VOLUMES_10_nearest_[25, 25, 25]_10000 15964 16994 32
ADD_POINTS_TO_VOLUMES_10_nearest_[25, 25, 25]_100000 16881 19286 30
ADD_POINTS_TO_VOLUMES_10_nearest_[101, 111, 121]_1000 19150 25277 27
ADD_POINTS_TO_VOLUMES_10_nearest_[101, 111, 121]_10000 18746 19999 27
ADD_POINTS_TO_VOLUMES_10_nearest_[101, 111, 121]_100000 22321 24568 23
ADD_POINTS_TO_VOLUMES_100_trilinear_[25, 25, 25]_1000 49693 50288 11
ADD_POINTS_TO_VOLUMES_100_trilinear_[25, 25, 25]_10000 51429 52449 10
ADD_POINTS_TO_VOLUMES_100_trilinear_[25, 25, 25]_100000 237076 237377 3
ADD_POINTS_TO_VOLUMES_100_trilinear_[101, 111, 121]_1000 81875 82597 7
ADD_POINTS_TO_VOLUMES_100_trilinear_[101, 111, 121]_10000 106671 107045 5
ADD_POINTS_TO_VOLUMES_100_trilinear_[101, 111, 121]_100000 483740 484607 2
ADD_POINTS_TO_VOLUMES_100_nearest_[25, 25, 25]_1000 16667 18143 31
ADD_POINTS_TO_VOLUMES_100_nearest_[25, 25, 25]_10000 17682 18922 29
ADD_POINTS_TO_VOLUMES_100_nearest_[25, 25, 25]_100000 65463 67116 8
ADD_POINTS_TO_VOLUMES_100_nearest_[101, 111, 121]_1000 48058 48826 11
ADD_POINTS_TO_VOLUMES_100_nearest_[101, 111, 121]_10000 53529 53998 10
ADD_POINTS_TO_VOLUMES_100_nearest_[101, 111, 121]_100000 123684 123901 5
--------------------------------------------------------------------------------
```
Output with `DEBUG=True`
{F338561209}
Reviewed By: nikhilaravi
Differential Revision: D22017500
fbshipit-source-id: ed3e8ed13940c593841d93211623dd533974012f
This commit is contained in:
David Novotny
committed by
Facebook GitHub Bot
Facebook GitHub Bot
parent
03ee1dbf82
commit
aa9bcaf04c
@@ -14,6 +14,10 @@ from .points_normals import (
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estimate_pointcloud_local_coord_frames,
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estimate_pointcloud_normals,
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)
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from .points_to_volumes import (
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add_pointclouds_to_volumes,
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add_points_features_to_volume_densities_features,
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)
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from .sample_points_from_meshes import sample_points_from_meshes
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from .subdivide_meshes import SubdivideMeshes
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from .utils import (
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491
pytorch3d/ops/points_to_volumes.py
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491
pytorch3d/ops/points_to_volumes.py
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@@ -0,0 +1,491 @@
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# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
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from typing import TYPE_CHECKING, Optional, Tuple
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import torch
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if TYPE_CHECKING:
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from ..structures import Pointclouds, Volumes
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def add_pointclouds_to_volumes(
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pointclouds: "Pointclouds",
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initial_volumes: "Volumes",
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mode: str = "trilinear",
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min_weight: float = 1e-4,
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) -> "Volumes":
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"""
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Add a batch of point clouds represented with a `Pointclouds` structure
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`pointclouds` to a batch of existing volumes represented with a
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`Volumes` structure `initial_volumes`.
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More specifically, the method casts a set of weighted votes (the weights are
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determined based on `mode="trilinear"|"nearest"`) into the pre-initialized
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`features` and `densities` fields of `initial_volumes`.
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The method returns an updated `Volumes` object that contains a copy
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of `initial_volumes` with its `features` and `densities` updated with the
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result of the pointcloud addition.
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Example:
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```
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# init a random point cloud
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pointclouds = Pointclouds(
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points=torch.randn(4, 100, 3), features=torch.rand(4, 100, 5)
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)
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# init an empty volume centered around [0.5, 0.5, 0.5] in world coordinates
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# with a voxel size of 1.0.
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initial_volumes = Volumes(
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features = torch.zeros(4, 5, 25, 25, 25),
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densities = torch.zeros(4, 1, 25, 25, 25),
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volume_translation = [-0.5, -0.5, -0.5],
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voxel_size = 1.0,
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)
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# add the pointcloud to the 'initial_volumes' buffer using
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# trilinear splatting
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updated_volumes = add_pointclouds_to_volumes(
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pointclouds=pointclouds,
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initial_volumes=initial_volumes,
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mode="trilinear",
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)
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```
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Args:
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pointclouds: Batch of 3D pointclouds represented with a `Pointclouds`
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structure. Note that `pointclouds.features` have to be defined.
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initial_volumes: Batch of initial `Volumes` with pre-initialized 1-dimensional
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densities which contain non-negative numbers corresponding to the
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opaqueness of each voxel (the higher, the less transparent).
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mode: The mode of the conversion of individual points into the volume.
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Set either to `nearest` or `trilinear`:
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`nearest`: Each 3D point is first rounded to the volumetric
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lattice. Each voxel is then labeled with the average
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over features that fall into the given voxel.
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The gradients of nearest neighbor conversion w.r.t. the
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3D locations of the points in `pointclouds` are *not* defined.
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`trilinear`: Each 3D point casts 8 weighted votes to the 8-neighborhood
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of its floating point coordinate. The weights are
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determined using a trilinear interpolation scheme.
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Trilinear splatting is fully differentiable w.r.t. all input arguments.
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min_weight: A scalar controlling the lowest possible total per-voxel
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weight used to normalize the features accumulated in a voxel.
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Only active for `mode==trilinear`.
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Returns:
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updated_volumes: Output `Volumes` structure containing the conversion result.
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"""
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if len(initial_volumes) != len(pointclouds):
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raise ValueError(
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"'initial_volumes' and 'pointclouds' have to have the same batch size."
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)
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# obtain the features and densities
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pcl_feats = pointclouds.features_padded()
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pcl_3d = pointclouds.points_padded()
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if pcl_feats is None:
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raise ValueError("'pointclouds' have to have their 'features' defined.")
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# obtain the conversion mask
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n_per_pcl = pointclouds.num_points_per_cloud().type_as(pcl_feats)
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mask = torch.arange(n_per_pcl.max(), dtype=pcl_feats.dtype, device=pcl_feats.device)
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mask = (mask[None, :] < n_per_pcl[:, None]).type_as(mask)
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# convert to the coord frame of the volume
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pcl_3d_local = initial_volumes.world_to_local_coords(pcl_3d)
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features_new, densities_new = add_points_features_to_volume_densities_features(
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points_3d=pcl_3d_local,
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points_features=pcl_feats,
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volume_features=initial_volumes.features(),
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volume_densities=initial_volumes.densities(),
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min_weight=min_weight,
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grid_sizes=initial_volumes.get_grid_sizes(),
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mask=mask,
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mode=mode,
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)
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return initial_volumes.update_padded(
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new_densities=densities_new, new_features=features_new
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)
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def add_points_features_to_volume_densities_features(
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points_3d: torch.Tensor,
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points_features: torch.Tensor,
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volume_densities: torch.Tensor,
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volume_features: Optional[torch.Tensor],
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mode: str = "trilinear",
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min_weight: float = 1e-4,
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mask: Optional[torch.Tensor] = None,
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grid_sizes: Optional[torch.LongTensor] = None,
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) -> Tuple[torch.Tensor, torch.Tensor]:
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"""
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Convert a batch of point clouds represented with tensors of per-point
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3d coordinates and their features to a batch of volumes represented
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with tensors of densities and features.
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Args:
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points_3d: Batch of 3D point cloud coordinates of shape
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`(minibatch, N, 3)` where N is the number of points
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in each point cloud. Coordinates have to be specified in the
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local volume coordinates (ranging in [-1, 1]).
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points_features: Features of shape `(minibatch, N, feature_dim)` corresponding
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to the points of the input point clouds `pointcloud`.
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volume_densities: Batch of input feature volume densities of shape
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`(minibatch, 1, D, H, W)`. Each voxel should
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contain a non-negative number corresponding to its
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opaqueness (the higher, the less transparent).
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volume_features: Batch of input feature volumes of shape
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`(minibatch, feature_dim, D, H, W)`
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If set to `None`, the `volume_features` will be automatically
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instantiatied with a correct size and filled with 0s.
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mode: The mode of the conversion of individual points into the volume.
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Set either to `nearest` or `trilinear`:
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`nearest`: Each 3D point is first rounded to the volumetric
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lattice. Each voxel is then labeled with the average
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over features that fall into the given voxel.
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The gradients of nearest neighbor rounding w.r.t. the
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input point locations `points_3d` are *not* defined.
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`trilinear`: Each 3D point casts 8 weighted votes to the 8-neighborhood
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of its floating point coordinate. The weights are
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determined using a trilinear interpolation scheme.
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Trilinear splatting is fully differentiable w.r.t. all input arguments.
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mask: A binary mask of shape `(minibatch, N)` determining which 3D points
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are going to be converted to the resulting volume.
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Set to `None` if all points are valid.
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min_weight: A scalar controlling the lowest possible total per-voxel
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weight used to normalize the features accumulated in a voxel.
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Only active for `mode==trilinear`.
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Returns:
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volume_features: Output volume of shape `(minibatch, feature_dim, D, H, W)`
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volume_densities: Occupancy volume of shape `(minibatch, 1, D, H, W)`
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containing the total amount of votes cast to each of the voxels.
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"""
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# number of points in the point cloud, its dim and batch size
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ba, n_points, feature_dim = points_features.shape
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ba_volume, density_dim = volume_densities.shape[:2]
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if density_dim != 1:
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raise ValueError("Only one-dimensional densities are allowed.")
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# init the volumetric grid sizes if uninitialized
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if grid_sizes is None:
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grid_sizes = torch.LongTensor(list(volume_densities.shape[2:])).to(
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volume_densities
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)
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# flatten densities and features
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v_shape = volume_densities.shape[2:]
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volume_densities_flatten = volume_densities.view(ba, -1, 1)
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n_voxels = volume_densities_flatten.shape[1]
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if volume_features is None:
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# initialize features if not passed in
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volume_features_flatten = volume_densities.new_zeros(ba, feature_dim, n_voxels)
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else:
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# otherwise just flatten
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volume_features_flatten = volume_features.view(ba, feature_dim, n_voxels)
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if mode == "trilinear": # do the splatting (trilinear interp)
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volume_features, volume_densities = splat_points_to_volumes(
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points_3d,
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points_features,
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volume_densities_flatten,
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volume_features_flatten,
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grid_sizes,
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mask=mask,
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min_weight=min_weight,
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)
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elif mode == "nearest": # nearest neighbor interp
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volume_features, volume_densities = round_points_to_volumes(
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points_3d,
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points_features,
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volume_densities_flatten,
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volume_features_flatten,
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grid_sizes,
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mask=mask,
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)
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else:
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raise ValueError('No such interpolation mode "%s"' % mode)
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# reshape into the volume shape
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volume_features = volume_features.view(ba, feature_dim, *v_shape)
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volume_densities = volume_densities.view(ba, 1, *v_shape)
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return volume_features, volume_densities
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def _check_points_to_volumes_inputs(
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points_3d: torch.Tensor,
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points_features: torch.Tensor,
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volume_densities: torch.Tensor,
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volume_features: torch.Tensor,
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grid_sizes: torch.LongTensor,
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mask: Optional[torch.Tensor] = None,
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):
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max_grid_size = grid_sizes.max(dim=0).values
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if torch.prod(max_grid_size) > volume_densities.shape[1]:
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raise ValueError(
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"One of the grid sizes corresponds to a larger number"
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+ " of elements than the number of elements in volume_densities."
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)
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_, n_voxels, density_dim = volume_densities.shape
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if density_dim != 1:
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raise ValueError("Only one-dimensional densities are allowed.")
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ba, n_points, feature_dim = points_features.shape
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if volume_features.shape[1] != feature_dim:
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raise ValueError(
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"volume_features have a different number of channels"
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+ " than points_features."
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)
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if volume_features.shape[2] != n_voxels:
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raise ValueError(
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"volume_features have a different number of elements"
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+ " than volume_densities."
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)
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def splat_points_to_volumes(
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points_3d: torch.Tensor,
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points_features: torch.Tensor,
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volume_densities: torch.Tensor,
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volume_features: torch.Tensor,
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grid_sizes: torch.LongTensor,
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min_weight: float = 1e-4,
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mask: Optional[torch.Tensor] = None,
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) -> Tuple[torch.Tensor, torch.Tensor]:
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"""
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Convert a batch of point clouds to a batch of volumes using trilinear
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splatting into a volume.
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Args:
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points_3d: Batch of 3D point cloud coordinates of shape
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`(minibatch, N, 3)` where N is the number of points
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in each point cloud. Coordinates have to be specified in the
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local volume coordinates (ranging in [-1, 1]).
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points_features: Features of shape `(minibatch, N, feature_dim)`
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corresponding to the points of the input point cloud `points_3d`.
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volume_features: Batch of input *flattened* feature volumes
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of shape `(minibatch, feature_dim, N_voxels)`
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volume_densities: Batch of input *flattened* feature volume densities
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of shape `(minibatch, 1, N_voxels)`. Each voxel should
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contain a non-negative number corresponding to its
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opaqueness (the higher, the less transparent).
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grid_sizes: `LongTensor` of shape (minibatch, 3) representing the
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spatial resolutions of each of the the non-flattened `volumes` tensors.
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Note that the following has to hold:
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`torch.prod(grid_sizes, dim=1)==N_voxels`
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mask: A binary mask of shape `(minibatch, N)` determining which 3D points
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are going to be converted to the resulting volume.
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Set to `None` if all points are valid.
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Returns:
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volume_features: Output volume of shape `(minibatch, D, N_voxels)`.
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volume_densities: Occupancy volume of shape `(minibatch, 1, N_voxels)`
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containing the total amount of votes cast to each of the voxels.
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"""
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_check_points_to_volumes_inputs(
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points_3d,
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points_features,
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volume_densities,
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volume_features,
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grid_sizes,
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mask=mask,
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)
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_, n_voxels, density_dim = volume_densities.shape
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ba, n_points, feature_dim = points_features.shape
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# minibatch x n_points x feature_dim -> minibatch x feature_dim x n_points
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points_features = points_features.permute(0, 2, 1).contiguous()
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# XYZ = the upper-left volume index of the 8-neigborhood of every point
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# grid_sizes is of the form (minibatch, depth-height-width)
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grid_sizes_xyz = grid_sizes[:, [2, 1, 0]]
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# Convert from points_3d in the range [-1, 1] to
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# indices in the volume grid in the range [0, grid_sizes_xyz-1]
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points_3d_indices = ((points_3d + 1) * 0.5) * (
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grid_sizes_xyz[:, None].type_as(points_3d) - 1
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)
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XYZ = points_3d_indices.floor().long()
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rXYZ = points_3d_indices - XYZ.type_as(points_3d) # remainder of floor
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# split into separate coordinate vectors
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X, Y, Z = XYZ.split(1, dim=2)
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# rX = remainder after floor = 1-"the weight of each vote into
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# the X coordinate of the 8-neighborhood"
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rX, rY, rZ = rXYZ.split(1, dim=2)
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# get random indices for the purpose of adding out-of-bounds values
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rand_idx = X.new_zeros(X.shape).random_(0, n_voxels)
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# iterate over the x, y, z indices of the 8-neighborhood (xdiff, ydiff, zdiff)
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for xdiff in (0, 1):
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X_ = X + xdiff
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wX = (1 - xdiff) + (2 * xdiff - 1) * rX
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for ydiff in (0, 1):
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Y_ = Y + ydiff
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wY = (1 - ydiff) + (2 * ydiff - 1) * rY
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for zdiff in (0, 1):
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Z_ = Z + zdiff
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wZ = (1 - zdiff) + (2 * zdiff - 1) * rZ
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# weight of each vote into the given cell of 8-neighborhood
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w = wX * wY * wZ
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# valid - binary indicators of votes that fall into the volume
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valid = (
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(0 <= X_)
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* (X_ < grid_sizes_xyz[:, None, 0:1])
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* (0 <= Y_)
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* (Y_ < grid_sizes_xyz[:, None, 1:2])
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* (0 <= Z_)
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* (Z_ < grid_sizes_xyz[:, None, 2:3])
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).long()
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# linearized indices into the volume
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idx = (Z_ * grid_sizes[:, None, 1:2] + Y_) * grid_sizes[
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:, None, 2:3
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] + X_
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# out-of-bounds features added to a random voxel idx with weight=0.
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idx_valid = idx * valid + rand_idx * (1 - valid)
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w_valid = w * valid.type_as(w)
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if mask is not None:
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w_valid = w_valid * mask.type_as(w)[:, :, None]
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|
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# scatter add casts the votes into the weight accumulator
|
||||
# and the feature accumulator
|
||||
volume_densities.scatter_add_(1, idx_valid, w_valid)
|
||||
|
||||
# reshape idx_valid -> (minibatch, feature_dim, n_points)
|
||||
idx_valid = idx_valid.view(ba, 1, n_points).expand_as(points_features)
|
||||
w_valid = w_valid.view(ba, 1, n_points)
|
||||
|
||||
# volume_features of shape (minibatch, feature_dim, n_voxels)
|
||||
volume_features.scatter_add_(2, idx_valid, w_valid * points_features)
|
||||
|
||||
# divide each feature by the total weight of the votes
|
||||
volume_features = volume_features / volume_densities.view(ba, 1, n_voxels).clamp(
|
||||
min_weight
|
||||
)
|
||||
|
||||
return volume_features, volume_densities
|
||||
|
||||
|
||||
def round_points_to_volumes(
|
||||
points_3d: torch.Tensor,
|
||||
points_features: torch.Tensor,
|
||||
volume_densities: torch.Tensor,
|
||||
volume_features: torch.Tensor,
|
||||
grid_sizes: torch.LongTensor,
|
||||
mask: Optional[torch.Tensor] = None,
|
||||
) -> Tuple[torch.Tensor, torch.Tensor]:
|
||||
"""
|
||||
Convert a batch of point clouds to a batch of volumes using rounding to the
|
||||
nearest integer coordinate of the volume. Features that fall into the same
|
||||
voxel are averaged.
|
||||
|
||||
Args:
|
||||
points_3d: Batch of 3D point cloud coordinates of shape
|
||||
`(minibatch, N, 3)` where N is the number of points
|
||||
in each point cloud. Coordinates have to be specified in the
|
||||
local volume coordinates (ranging in [-1, 1]).
|
||||
points_features: Features of shape `(minibatch, N, feature_dim)`
|
||||
corresponding to the points of the input point cloud `points_3d`.
|
||||
volume_features: Batch of input *flattened* feature volumes
|
||||
of shape `(minibatch, feature_dim, N_voxels)`
|
||||
volume_densities: Batch of input *flattened* feature volume densities
|
||||
of shape `(minibatch, 1, N_voxels)`. Each voxel should
|
||||
contain a non-negative number corresponding to its
|
||||
opaqueness (the higher, the less transparent).
|
||||
grid_sizes: `LongTensor` of shape (minibatch, 3) representing the
|
||||
spatial resolutions of each of the the non-flattened `volumes` tensors.
|
||||
Note that the following has to hold:
|
||||
`torch.prod(grid_sizes, dim=1)==N_voxels`
|
||||
mask: A binary mask of shape `(minibatch, N)` determining which 3D points
|
||||
are going to be converted to the resulting volume.
|
||||
Set to `None` if all points are valid.
|
||||
Returns:
|
||||
volume_features: Output volume of shape `(minibatch, D, N_voxels)`.
|
||||
volume_densities: Occupancy volume of shape `(minibatch, 1, N_voxels)`
|
||||
containing the total amount of votes cast to each of the voxels.
|
||||
"""
|
||||
|
||||
_check_points_to_volumes_inputs(
|
||||
points_3d,
|
||||
points_features,
|
||||
volume_densities,
|
||||
volume_features,
|
||||
grid_sizes,
|
||||
mask=mask,
|
||||
)
|
||||
|
||||
_, n_voxels, density_dim = volume_densities.shape
|
||||
ba, n_points, feature_dim = points_features.shape
|
||||
|
||||
# minibatch x n_points x feature_dim-> minibatch x feature_dim x n_points
|
||||
points_features = points_features.permute(0, 2, 1).contiguous()
|
||||
|
||||
# round the coordinates to nearest integer
|
||||
# grid_sizes is of the form (minibatch, depth-height-width)
|
||||
grid_sizes_xyz = grid_sizes[:, [2, 1, 0]]
|
||||
XYZ = ((points_3d.detach() + 1) * 0.5) * (
|
||||
grid_sizes_xyz[:, None].type_as(points_3d) - 1
|
||||
)
|
||||
XYZ = torch.round(XYZ).long()
|
||||
|
||||
# split into separate coordinate vectors
|
||||
X, Y, Z = XYZ.split(1, dim=2)
|
||||
|
||||
# get random indices for the purpose of adding out-of-bounds values
|
||||
rand_idx = X.new_zeros(X.shape).random_(0, n_voxels)
|
||||
|
||||
# valid - binary indicators of votes that fall into the volume
|
||||
grid_sizes = grid_sizes.type_as(XYZ)
|
||||
valid = (
|
||||
(0 <= X)
|
||||
* (X < grid_sizes_xyz[:, None, 0:1])
|
||||
* (0 <= Y)
|
||||
* (Y < grid_sizes_xyz[:, None, 1:2])
|
||||
* (0 <= Z)
|
||||
* (Z < grid_sizes_xyz[:, None, 2:3])
|
||||
).long()
|
||||
|
||||
# get random indices for the purpose of adding out-of-bounds values
|
||||
rand_idx = valid.new_zeros(X.shape).random_(0, n_voxels)
|
||||
|
||||
# linearized indices into the volume
|
||||
idx = (Z * grid_sizes[:, None, 1:2] + Y) * grid_sizes[:, None, 2:3] + X
|
||||
|
||||
# out-of-bounds features added to a random voxel idx with weight=0.
|
||||
idx_valid = idx * valid + rand_idx * (1 - valid)
|
||||
w_valid = valid.type_as(volume_features)
|
||||
|
||||
# scatter add casts the votes into the weight accumulator
|
||||
# and the feature accumulator
|
||||
volume_densities.scatter_add_(1, idx_valid, w_valid)
|
||||
|
||||
# reshape idx_valid -> (minibatch, feature_dim, n_points)
|
||||
idx_valid = idx_valid.view(ba, 1, n_points).expand_as(points_features)
|
||||
w_valid = w_valid.view(ba, 1, n_points)
|
||||
|
||||
# volume_features of shape (minibatch, feature_dim, n_voxels)
|
||||
volume_features.scatter_add_(2, idx_valid, w_valid * points_features)
|
||||
|
||||
# divide each feature by the total weight of the votes
|
||||
volume_features = volume_features / volume_densities.view(ba, 1, n_voxels).clamp(
|
||||
1.0
|
||||
)
|
||||
|
||||
return volume_features, volume_densities
|
||||
Reference in New Issue
Block a user