pytorch3d/pytorch3d/common/workaround.py
Alexey Sidnev bcee361d04 Replace torch.det() with manual implementation for 3x3 matrix
Summary:
# Background
There is an unstable error during training (it can happen after several minutes or after several hours).
The error is connected to `torch.det()` function in  `_check_valid_rotation_matrix()`.

if I remove the function `torch.det()` in `_check_valid_rotation_matrix()` or remove the whole functions `_check_valid_rotation_matrix()` the error is disappeared (D29555876).

# Solution
Replace `torch.det()` with manual implementation for 3x3 matrix.

Reviewed By: patricklabatut

Differential Revision: D29655924

fbshipit-source-id: 41bde1119274a705ab849751ece28873d2c45155
2021-07-19 05:02:51 -07:00

32 lines
870 B
Python

# Copyright (c) Facebook, Inc. and its affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.
import torch
def _safe_det_3x3(t: torch.Tensor):
"""
Fast determinant calculation for a batch of 3x3 matrices.
Note, result of this function might not be the same as `torch.det()`.
The differences might be in the last significant digit.
Args:
t: Tensor of shape (N, 3, 3).
Returns:
Tensor of shape (N) with determinants.
"""
det = (
t[..., 0, 0] * (t[..., 1, 1] * t[..., 2, 2] - t[..., 1, 2] * t[..., 2, 1])
- t[..., 0, 1] * (t[..., 1, 0] * t[..., 2, 2] - t[..., 2, 0] * t[..., 1, 2])
+ t[..., 0, 2] * (t[..., 1, 0] * t[..., 2, 1] - t[..., 2, 0] * t[..., 1, 1])
)
return det