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# Modified from https://github.com/facebookresearch/detectron2/tree/master/projects/PointRend # noqa
from os import path as osp
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.nn.modules.utils import _pair
from torch.onnx.operators import shape_as_tensor
def bilinear_grid_sample(im, grid, align_corners=False):
"""Given an input and a flow-field grid, computes the output using input
values and pixel locations from grid. Supported only bilinear interpolation
method to sample the input pixels.
Args:
im (torch.Tensor): Input feature map, shape (N, C, H, W)
grid (torch.Tensor): Point coordinates, shape (N, Hg, Wg, 2)
align_corners {bool}: If set to True, the extrema (-1 and 1) are
considered as referring to the center points of the inputโ€™s
corner pixels. If set to False, they are instead considered as
referring to the corner points of the inputโ€™s corner pixels,
making the sampling more resolution agnostic.
Returns:
torch.Tensor: A tensor with sampled points, shape (N, C, Hg, Wg)
"""
n, c, h, w = im.shape
gn, gh, gw, _ = grid.shape
assert n == gn
x = grid[:, :, :, 0]
y = grid[:, :, :, 1]
if align_corners:
x = ((x + 1) / 2) * (w - 1)
y = ((y + 1) / 2) * (h - 1)
else:
x = ((x + 1) * w - 1) / 2
y = ((y + 1) * h - 1) / 2
x = x.view(n, -1)
y = y.view(n, -1)
x0 = torch.floor(x).long()
y0 = torch.floor(y).long()
x1 = x0 + 1
y1 = y0 + 1
wa = ((x1 - x) * (y1 - y)).unsqueeze(1)
wb = ((x1 - x) * (y - y0)).unsqueeze(1)
wc = ((x - x0) * (y1 - y)).unsqueeze(1)
wd = ((x - x0) * (y - y0)).unsqueeze(1)
# Apply default for grid_sample function zero padding
im_padded = F.pad(im, pad=[1, 1, 1, 1], mode='constant', value=0)
padded_h = h + 2
padded_w = w + 2
# save points positions after padding
x0, x1, y0, y1 = x0 + 1, x1 + 1, y0 + 1, y1 + 1
# Clip coordinates to padded image size
x0 = torch.where(x0 < 0, torch.tensor(0), x0)
x0 = torch.where(x0 > padded_w - 1, torch.tensor(padded_w - 1), x0)
x1 = torch.where(x1 < 0, torch.tensor(0), x1)
x1 = torch.where(x1 > padded_w - 1, torch.tensor(padded_w - 1), x1)
y0 = torch.where(y0 < 0, torch.tensor(0), y0)
y0 = torch.where(y0 > padded_h - 1, torch.tensor(padded_h - 1), y0)
y1 = torch.where(y1 < 0, torch.tensor(0), y1)
y1 = torch.where(y1 > padded_h - 1, torch.tensor(padded_h - 1), y1)
im_padded = im_padded.view(n, c, -1)
x0_y0 = (x0 + y0 * padded_w).unsqueeze(1).expand(-1, c, -1)
x0_y1 = (x0 + y1 * padded_w).unsqueeze(1).expand(-1, c, -1)
x1_y0 = (x1 + y0 * padded_w).unsqueeze(1).expand(-1, c, -1)
x1_y1 = (x1 + y1 * padded_w).unsqueeze(1).expand(-1, c, -1)
Ia = torch.gather(im_padded, 2, x0_y0)
Ib = torch.gather(im_padded, 2, x0_y1)
Ic = torch.gather(im_padded, 2, x1_y0)
Id = torch.gather(im_padded, 2, x1_y1)
return (Ia * wa + Ib * wb + Ic * wc + Id * wd).reshape(n, c, gh, gw)
def is_in_onnx_export_without_custom_ops():
from annotator.mmpkg.mmcv.ops import get_onnxruntime_op_path
ort_custom_op_path = get_onnxruntime_op_path()
return torch.onnx.is_in_onnx_export(
) and not osp.exists(ort_custom_op_path)
def normalize(grid):
"""Normalize input grid from [-1, 1] to [0, 1]
Args:
grid (Tensor): The grid to be normalize, range [-1, 1].
Returns:
Tensor: Normalized grid, range [0, 1].
"""
return (grid + 1.0) / 2.0
def denormalize(grid):
"""Denormalize input grid from range [0, 1] to [-1, 1]
Args:
grid (Tensor): The grid to be denormalize, range [0, 1].
Returns:
Tensor: Denormalized grid, range [-1, 1].
"""
return grid * 2.0 - 1.0
def generate_grid(num_grid, size, device):
"""Generate regular square grid of points in [0, 1] x [0, 1] coordinate
space.
Args:
num_grid (int): The number of grids to sample, one for each region.
size (tuple(int, int)): The side size of the regular grid.
device (torch.device): Desired device of returned tensor.
Returns:
(torch.Tensor): A tensor of shape (num_grid, size[0]*size[1], 2) that
contains coordinates for the regular grids.
"""
affine_trans = torch.tensor([[[1., 0., 0.], [0., 1., 0.]]], device=device)
grid = F.affine_grid(
affine_trans, torch.Size((1, 1, *size)), align_corners=False)
grid = normalize(grid)
return grid.view(1, -1, 2).expand(num_grid, -1, -1)
def rel_roi_point_to_abs_img_point(rois, rel_roi_points):
"""Convert roi based relative point coordinates to image based absolute
point coordinates.
Args:
rois (Tensor): RoIs or BBoxes, shape (N, 4) or (N, 5)
rel_roi_points (Tensor): Point coordinates inside RoI, relative to
RoI, location, range (0, 1), shape (N, P, 2)
Returns:
Tensor: Image based absolute point coordinates, shape (N, P, 2)
"""
with torch.no_grad():
assert rel_roi_points.size(0) == rois.size(0)
assert rois.dim() == 2
assert rel_roi_points.dim() == 3
assert rel_roi_points.size(2) == 2
# remove batch idx
if rois.size(1) == 5:
rois = rois[:, 1:]
abs_img_points = rel_roi_points.clone()
# To avoid an error during exporting to onnx use independent
# variables instead inplace computation
xs = abs_img_points[:, :, 0] * (rois[:, None, 2] - rois[:, None, 0])
ys = abs_img_points[:, :, 1] * (rois[:, None, 3] - rois[:, None, 1])
xs += rois[:, None, 0]
ys += rois[:, None, 1]
abs_img_points = torch.stack([xs, ys], dim=2)
return abs_img_points
def get_shape_from_feature_map(x):
"""Get spatial resolution of input feature map considering exporting to
onnx mode.
Args:
x (torch.Tensor): Input tensor, shape (N, C, H, W)
Returns:
torch.Tensor: Spatial resolution (width, height), shape (1, 1, 2)
"""
if torch.onnx.is_in_onnx_export():
img_shape = shape_as_tensor(x)[2:].flip(0).view(1, 1, 2).to(
x.device).float()
else:
img_shape = torch.tensor(x.shape[2:]).flip(0).view(1, 1, 2).to(
x.device).float()
return img_shape
def abs_img_point_to_rel_img_point(abs_img_points, img, spatial_scale=1.):
"""Convert image based absolute point coordinates to image based relative
coordinates for sampling.
Args:
abs_img_points (Tensor): Image based absolute point coordinates,
shape (N, P, 2)
img (tuple/Tensor): (height, width) of image or feature map.
spatial_scale (float): Scale points by this factor. Default: 1.
Returns:
Tensor: Image based relative point coordinates for sampling,
shape (N, P, 2)
"""
assert (isinstance(img, tuple) and len(img) == 2) or \
(isinstance(img, torch.Tensor) and len(img.shape) == 4)
if isinstance(img, tuple):
h, w = img
scale = torch.tensor([w, h],
dtype=torch.float,
device=abs_img_points.device)
scale = scale.view(1, 1, 2)
else:
scale = get_shape_from_feature_map(img)
return abs_img_points / scale * spatial_scale
def rel_roi_point_to_rel_img_point(rois,
rel_roi_points,
img,
spatial_scale=1.):
"""Convert roi based relative point coordinates to image based absolute
point coordinates.
Args:
rois (Tensor): RoIs or BBoxes, shape (N, 4) or (N, 5)
rel_roi_points (Tensor): Point coordinates inside RoI, relative to
RoI, location, range (0, 1), shape (N, P, 2)
img (tuple/Tensor): (height, width) of image or feature map.
spatial_scale (float): Scale points by this factor. Default: 1.
Returns:
Tensor: Image based relative point coordinates for sampling,
shape (N, P, 2)
"""
abs_img_point = rel_roi_point_to_abs_img_point(rois, rel_roi_points)
rel_img_point = abs_img_point_to_rel_img_point(abs_img_point, img,
spatial_scale)
return rel_img_point
def point_sample(input, points, align_corners=False, **kwargs):
"""A wrapper around :func:`grid_sample` to support 3D point_coords tensors
Unlike :func:`torch.nn.functional.grid_sample` it assumes point_coords to
lie inside ``[0, 1] x [0, 1]`` square.
Args:
input (Tensor): Feature map, shape (N, C, H, W).
points (Tensor): Image based absolute point coordinates (normalized),
range [0, 1] x [0, 1], shape (N, P, 2) or (N, Hgrid, Wgrid, 2).
align_corners (bool): Whether align_corners. Default: False
Returns:
Tensor: Features of `point` on `input`, shape (N, C, P) or
(N, C, Hgrid, Wgrid).
"""
add_dim = False
if points.dim() == 3:
add_dim = True
points = points.unsqueeze(2)
if is_in_onnx_export_without_custom_ops():
# If custom ops for onnx runtime not compiled use python
# implementation of grid_sample function to make onnx graph
# with supported nodes
output = bilinear_grid_sample(
input, denormalize(points), align_corners=align_corners)
else:
output = F.grid_sample(
input, denormalize(points), align_corners=align_corners, **kwargs)
if add_dim:
output = output.squeeze(3)
return output
class SimpleRoIAlign(nn.Module):
def __init__(self, output_size, spatial_scale, aligned=True):
"""Simple RoI align in PointRend, faster than standard RoIAlign.
Args:
output_size (tuple[int]): h, w
spatial_scale (float): scale the input boxes by this number
aligned (bool): if False, use the legacy implementation in
MMDetection, align_corners=True will be used in F.grid_sample.
If True, align the results more perfectly.
"""
super(SimpleRoIAlign, self).__init__()
self.output_size = _pair(output_size)
self.spatial_scale = float(spatial_scale)
# to be consistent with other RoI ops
self.use_torchvision = False
self.aligned = aligned
def forward(self, features, rois):
num_imgs = features.size(0)
num_rois = rois.size(0)
rel_roi_points = generate_grid(
num_rois, self.output_size, device=rois.device)
if torch.onnx.is_in_onnx_export():
rel_img_points = rel_roi_point_to_rel_img_point(
rois, rel_roi_points, features, self.spatial_scale)
rel_img_points = rel_img_points.reshape(num_imgs, -1,
*rel_img_points.shape[1:])
point_feats = point_sample(
features, rel_img_points, align_corners=not self.aligned)
point_feats = point_feats.transpose(1, 2)
else:
point_feats = []
for batch_ind in range(num_imgs):
# unravel batch dim
feat = features[batch_ind].unsqueeze(0)
inds = (rois[:, 0].long() == batch_ind)
if inds.any():
rel_img_points = rel_roi_point_to_rel_img_point(
rois[inds], rel_roi_points[inds], feat,
self.spatial_scale).unsqueeze(0)
point_feat = point_sample(
feat, rel_img_points, align_corners=not self.aligned)
point_feat = point_feat.squeeze(0).transpose(0, 1)
point_feats.append(point_feat)
point_feats = torch.cat(point_feats, dim=0)
channels = features.size(1)
roi_feats = point_feats.reshape(num_rois, channels, *self.output_size)
return roi_feats
def __repr__(self):
format_str = self.__class__.__name__
format_str += '(output_size={}, spatial_scale={}'.format(
self.output_size, self.spatial_scale)
return format_str