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# Copyright (c) OpenMMLab. All rights reserved. | |
import torch | |
from torch import nn as nn | |
from torch.autograd import Function | |
import annotator.uniformer.mmcv as mmcv | |
from ..utils import ext_loader | |
ext_module = ext_loader.load_ext( | |
'_ext', ['roiaware_pool3d_forward', 'roiaware_pool3d_backward']) | |
class RoIAwarePool3d(nn.Module): | |
"""Encode the geometry-specific features of each 3D proposal. | |
Please refer to `PartA2 <https://arxiv.org/pdf/1907.03670.pdf>`_ for more | |
details. | |
Args: | |
out_size (int or tuple): The size of output features. n or | |
[n1, n2, n3]. | |
max_pts_per_voxel (int, optional): The maximum number of points per | |
voxel. Default: 128. | |
mode (str, optional): Pooling method of RoIAware, 'max' or 'avg'. | |
Default: 'max'. | |
""" | |
def __init__(self, out_size, max_pts_per_voxel=128, mode='max'): | |
super().__init__() | |
self.out_size = out_size | |
self.max_pts_per_voxel = max_pts_per_voxel | |
assert mode in ['max', 'avg'] | |
pool_mapping = {'max': 0, 'avg': 1} | |
self.mode = pool_mapping[mode] | |
def forward(self, rois, pts, pts_feature): | |
""" | |
Args: | |
rois (torch.Tensor): [N, 7], in LiDAR coordinate, | |
(x, y, z) is the bottom center of rois. | |
pts (torch.Tensor): [npoints, 3], coordinates of input points. | |
pts_feature (torch.Tensor): [npoints, C], features of input points. | |
Returns: | |
pooled_features (torch.Tensor): [N, out_x, out_y, out_z, C] | |
""" | |
return RoIAwarePool3dFunction.apply(rois, pts, pts_feature, | |
self.out_size, | |
self.max_pts_per_voxel, self.mode) | |
class RoIAwarePool3dFunction(Function): | |
def forward(ctx, rois, pts, pts_feature, out_size, max_pts_per_voxel, | |
mode): | |
""" | |
Args: | |
rois (torch.Tensor): [N, 7], in LiDAR coordinate, | |
(x, y, z) is the bottom center of rois. | |
pts (torch.Tensor): [npoints, 3], coordinates of input points. | |
pts_feature (torch.Tensor): [npoints, C], features of input points. | |
out_size (int or tuple): The size of output features. n or | |
[n1, n2, n3]. | |
max_pts_per_voxel (int): The maximum number of points per voxel. | |
Default: 128. | |
mode (int): Pooling method of RoIAware, 0 (max pool) or 1 (average | |
pool). | |
Returns: | |
pooled_features (torch.Tensor): [N, out_x, out_y, out_z, C], output | |
pooled features. | |
""" | |
if isinstance(out_size, int): | |
out_x = out_y = out_z = out_size | |
else: | |
assert len(out_size) == 3 | |
assert mmcv.is_tuple_of(out_size, int) | |
out_x, out_y, out_z = out_size | |
num_rois = rois.shape[0] | |
num_channels = pts_feature.shape[-1] | |
num_pts = pts.shape[0] | |
pooled_features = pts_feature.new_zeros( | |
(num_rois, out_x, out_y, out_z, num_channels)) | |
argmax = pts_feature.new_zeros( | |
(num_rois, out_x, out_y, out_z, num_channels), dtype=torch.int) | |
pts_idx_of_voxels = pts_feature.new_zeros( | |
(num_rois, out_x, out_y, out_z, max_pts_per_voxel), | |
dtype=torch.int) | |
ext_module.roiaware_pool3d_forward(rois, pts, pts_feature, argmax, | |
pts_idx_of_voxels, pooled_features, | |
mode) | |
ctx.roiaware_pool3d_for_backward = (pts_idx_of_voxels, argmax, mode, | |
num_pts, num_channels) | |
return pooled_features | |
def backward(ctx, grad_out): | |
ret = ctx.roiaware_pool3d_for_backward | |
pts_idx_of_voxels, argmax, mode, num_pts, num_channels = ret | |
grad_in = grad_out.new_zeros((num_pts, num_channels)) | |
ext_module.roiaware_pool3d_backward(pts_idx_of_voxels, argmax, | |
grad_out.contiguous(), grad_in, | |
mode) | |
return None, None, grad_in, None, None, None | |