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# Copyright (c) OpenMMLab. All rights reserved. | |
import torch | |
from torch.autograd import Function | |
from ..utils import ext_loader | |
ext_module = ext_loader.load_ext('_ext', ['ball_query_forward']) | |
class BallQuery(Function): | |
"""Find nearby points in spherical space.""" | |
def forward(ctx, min_radius: float, max_radius: float, sample_num: int, | |
xyz: torch.Tensor, center_xyz: torch.Tensor) -> torch.Tensor: | |
""" | |
Args: | |
min_radius (float): minimum radius of the balls. | |
max_radius (float): maximum radius of the balls. | |
sample_num (int): maximum number of features in the balls. | |
xyz (Tensor): (B, N, 3) xyz coordinates of the features. | |
center_xyz (Tensor): (B, npoint, 3) centers of the ball query. | |
Returns: | |
Tensor: (B, npoint, nsample) tensor with the indices of | |
the features that form the query balls. | |
""" | |
assert center_xyz.is_contiguous() | |
assert xyz.is_contiguous() | |
assert min_radius < max_radius | |
B, N, _ = xyz.size() | |
npoint = center_xyz.size(1) | |
idx = xyz.new_zeros(B, npoint, sample_num, dtype=torch.int) | |
ext_module.ball_query_forward( | |
center_xyz, | |
xyz, | |
idx, | |
b=B, | |
n=N, | |
m=npoint, | |
min_radius=min_radius, | |
max_radius=max_radius, | |
nsample=sample_num) | |
if torch.__version__ != 'parrots': | |
ctx.mark_non_differentiable(idx) | |
return idx | |
def backward(ctx, a=None): | |
return None, None, None, None | |
ball_query = BallQuery.apply | |