HRNet/hrnet.py

import logging

import torch
import torch.nn as nn
import torch.nn.functional as F


BatchNorm2d = nn.BatchNorm2d
BN_MOMENTUM = 0.01
logger = logging.getLogger(__name__)


def conv3x3(in_planes, out_planes, stride=1):
    """3x3 convolution with padding"""
    return nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride, padding=1, bias=False)


class BasicBlock(nn.Module):
    expansion = 1

    def __init__(self, inplanes, planes, stride=1, downsample=None):
        super(BasicBlock, self).__init__()
        self.conv1 = conv3x3(inplanes, planes, stride)
        self.bn1 = BatchNorm2d(planes, momentum=BN_MOMENTUM)
        self.relu = nn.ReLU(inplace=True)
        self.conv2 = conv3x3(planes, planes)
        self.bn2 = BatchNorm2d(planes, momentum=BN_MOMENTUM)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        residual = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)

        if self.downsample is not None:
            residual = self.downsample(x)

        out += residual
        out = self.relu(out)

        return out


class Bottleneck(nn.Module):
    expansion = 4

    def __init__(self, inplanes, planes, stride=1, downsample=None):
        super(Bottleneck, self).__init__()
        self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
        self.bn1 = BatchNorm2d(planes, momentum=BN_MOMENTUM)
        self.conv2 = nn.Conv2d(planes, planes, kernel_size=3, stride=stride, padding=1, bias=False)
        self.bn2 = BatchNorm2d(planes, momentum=BN_MOMENTUM)
        self.conv3 = nn.Conv2d(planes, planes * self.expansion, kernel_size=1, bias=False)
        self.bn3 = BatchNorm2d(planes * self.expansion, momentum=BN_MOMENTUM)
        self.relu = nn.ReLU(inplace=True)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        residual = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)
        out = self.relu(out)

        out = self.conv3(out)
        out = self.bn3(out)

        if self.downsample is not None:
            residual = self.downsample(x)

        out += residual
        out = self.relu(out)

        return out


class HighResolutionModule(nn.Module):
    def __init__(
        self, num_branches, blocks, num_blocks, num_inchannels, num_channels, fuse_method, multi_scale_output=True
    ):
        super(HighResolutionModule, self).__init__()
        # self._check_branches(
        #     num_branches, blocks, num_blocks, num_inchannels, num_channels)

        self.num_inchannels = num_inchannels
        self.fuse_method = fuse_method
        self.num_branches = num_branches

        self.multi_scale_output = multi_scale_output

        self.branches = self._make_branches(num_branches, blocks, num_blocks, num_channels)
        self.fuse_layers = self._make_fuse_layers()
        self.relu = nn.ReLU(inplace=True)

    # def _check_branches(self, num_branches, blocks, num_blocks,
    #                     num_inchannels, num_channels):
    #     if num_branches != len(num_blocks):
    #         error_msg = 'NUM_BRANCHES({}) <> NUM_BLOCKS({})'.format(
    #             num_branches, len(num_blocks))
    #         logger.error(error_msg)
    #         raise ValueError(error_msg)

    #     if num_branches != len(num_channels):
    #         error_msg = 'NUM_BRANCHES({}) <> NUM_CHANNELS({})'.format(
    #             num_branches, len(num_channels))
    #         logger.error(error_msg)
    #         raise ValueError(error_msg)

    #     if num_branches != len(num_inchannels):
    #         error_msg = 'NUM_BRANCHES({}) <> NUM_INCHANNELS({})'.format(
    #             num_branches, len(num_inchannels))
    #         logger.error(error_msg)
    #         raise ValueError(error_msg)

    def _make_one_branch(self, branch_index, block, num_blocks, num_channels, stride=1):
        downsample = None
        if stride != 1 or self.num_inchannels[branch_index] != num_channels[branch_index] * block.expansion:
            downsample = nn.Sequential(
                nn.Conv2d(
                    self.num_inchannels[branch_index],
                    num_channels[branch_index] * block.expansion,
                    kernel_size=1,
                    stride=stride,
                    bias=False,
                ),
                BatchNorm2d(num_channels[branch_index] * block.expansion, momentum=BN_MOMENTUM),
            )

        layers = []
        layers.append(block(self.num_inchannels[branch_index], num_channels[branch_index], stride, downsample))
        self.num_inchannels[branch_index] = num_channels[branch_index] * block.expansion
        for i in range(1, num_blocks[branch_index]):
            layers.append(block(self.num_inchannels[branch_index], num_channels[branch_index]))

        return nn.Sequential(*layers)

    def _make_branches(self, num_branches, block, num_blocks, num_channels):
        branches = []

        for i in range(num_branches):
            branches.append(self._make_one_branch(i, block, num_blocks, num_channels))

        return nn.ModuleList(branches)

    def _make_fuse_layers(self):
        if self.num_branches == 1:
            return None

        num_branches = self.num_branches
        num_inchannels = self.num_inchannels
        fuse_layers = []
        for i in range(num_branches if self.multi_scale_output else 1):
            fuse_layer = []
            for j in range(num_branches):
                if j > i:
                    fuse_layer.append(
                        nn.Sequential(
                            nn.Conv2d(num_inchannels[j], num_inchannels[i], 1, 1, 0, bias=False),
                            BatchNorm2d(num_inchannels[i], momentum=BN_MOMENTUM),
                        )
                    )
                    # nn.Upsample(scale_factor=2**(j-i), mode='nearest')))
                elif j == i:
                    fuse_layer.append(None)
                else:
                    conv3x3s = []
                    for k in range(i - j):
                        if k == i - j - 1:
                            num_outchannels_conv3x3 = num_inchannels[i]
                            conv3x3s.append(
                                nn.Sequential(
                                    nn.Conv2d(num_inchannels[j], num_outchannels_conv3x3, 3, 2, 1, bias=False),
                                    BatchNorm2d(num_outchannels_conv3x3, momentum=BN_MOMENTUM),
                                )
                            )
                        else:
                            num_outchannels_conv3x3 = num_inchannels[j]
                            conv3x3s.append(
                                nn.Sequential(
                                    nn.Conv2d(num_inchannels[j], num_outchannels_conv3x3, 3, 2, 1, bias=False),
                                    BatchNorm2d(num_outchannels_conv3x3, momentum=BN_MOMENTUM),
                                    nn.ReLU(inplace=True),
                                )
                            )
                    fuse_layer.append(nn.Sequential(*conv3x3s))
            fuse_layers.append(nn.ModuleList(fuse_layer))

        return nn.ModuleList(fuse_layers)

    def get_num_inchannels(self):
        return self.num_inchannels

    def forward(self, x):
        if self.num_branches == 1:
            return [self.branches[0](x[0])]

        for i in range(self.num_branches):
            x[i] = self.branches[i](x[i])

        x_fuse = []
        for i in range(len(self.fuse_layers)):
            y = x[0] if i == 0 else self.fuse_layers[i][0](x[0])
            for j in range(1, self.num_branches):
                if i == j:
                    y = y + x[j]
                elif j > i:
                    y = y + F.interpolate(
                        self.fuse_layers[i][j](x[j]), size=[x[i].shape[2], x[i].shape[3]], mode="bilinear"
                    )
                else:
                    y = y + self.fuse_layers[i][j](x[j])
            x_fuse.append(self.relu(y))

        return x_fuse


blocks_dict = {"BASIC": BasicBlock, "BOTTLENECK": Bottleneck}


class HighResolutionNet(nn.Module):
    def __init__(
        self,
    ):
        self.inplanes = 64
        super(HighResolutionNet, self).__init__()

        # stem net
        self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=2, padding=1, bias=False)
        self.bn1 = BatchNorm2d(64, momentum=BN_MOMENTUM)
        self.conv2 = nn.Conv2d(64, 64, kernel_size=3, stride=2, padding=1, bias=False)
        self.bn2 = BatchNorm2d(64, momentum=BN_MOMENTUM)
        self.relu = nn.ReLU(inplace=True)
        self.sf = nn.Softmax(dim=1)
        self.layer1 = self._make_layer(Bottleneck, 64, 64, 4)

        num_channels = [18, 36]
        block = blocks_dict["BASIC"]
        num_channels = [num_channels[i] * block.expansion for i in range(len(num_channels))]
        self.transition1 = self._make_transition_layer([256], num_channels)
        config_list = [1, 2, [4, 4], [18, 36], "BASIC", "SUM"]
        self.stage2, pre_stage_channels = self._make_stage(config_list, num_channels)

        num_channels = [18, 36, 72]
        block = blocks_dict["BASIC"]
        num_channels = [num_channels[i] * block.expansion for i in range(len(num_channels))]
        self.transition2 = self._make_transition_layer(pre_stage_channels, num_channels)
        config_list = [4, 3, [4, 4, 4], [18, 36, 72], "BASIC", "SUM"]
        self.stage3, pre_stage_channels = self._make_stage(config_list, num_channels)

        num_channels = [18, 36, 72, 144]
        block = blocks_dict["BASIC"]
        num_channels = [num_channels[i] * block.expansion for i in range(len(num_channels))]
        self.transition3 = self._make_transition_layer(pre_stage_channels, num_channels)
        config_list = [3, 4, [4, 4, 4, 4], [18, 36, 72, 144], "BASIC", "SUM"]
        self.stage4, pre_stage_channels = self._make_stage(config_list, num_channels, multi_scale_output=True)

        final_inp_channels = sum(pre_stage_channels)

        self.head = nn.Sequential(
            nn.Conv2d(
                in_channels=final_inp_channels, out_channels=final_inp_channels, kernel_size=1, stride=1, padding=0
            ),
            BatchNorm2d(final_inp_channels, momentum=BN_MOMENTUM),
            nn.ReLU(inplace=True),
            nn.Conv2d(in_channels=final_inp_channels, out_channels=98, kernel_size=1, stride=1, padding=0),
        )

    def _make_transition_layer(self, num_channels_pre_layer, num_channels_cur_layer):
        num_branches_cur = len(num_channels_cur_layer)
        num_branches_pre = len(num_channels_pre_layer)

        transition_layers = []
        for i in range(num_branches_cur):
            if i < num_branches_pre:
                if num_channels_cur_layer[i] != num_channels_pre_layer[i]:
                    transition_layers.append(
                        nn.Sequential(
                            nn.Conv2d(num_channels_pre_layer[i], num_channels_cur_layer[i], 3, 1, 1, bias=False),
                            BatchNorm2d(num_channels_cur_layer[i], momentum=BN_MOMENTUM),
                            nn.ReLU(inplace=True),
                        )
                    )
                else:
                    transition_layers.append(None)
            else:
                conv3x3s = []
                for j in range(i + 1 - num_branches_pre):
                    inchannels = num_channels_pre_layer[-1]
                    outchannels = num_channels_cur_layer[i] if j == i - num_branches_pre else inchannels
                    conv3x3s.append(
                        nn.Sequential(
                            nn.Conv2d(inchannels, outchannels, 3, 2, 1, bias=False),
                            BatchNorm2d(outchannels, momentum=BN_MOMENTUM),
                            nn.ReLU(inplace=True),
                        )
                    )
                transition_layers.append(nn.Sequential(*conv3x3s))

        return nn.ModuleList(transition_layers)

    def _make_layer(self, block, inplanes, planes, blocks, stride=1):
        downsample = None
        if stride != 1 or inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                nn.Conv2d(inplanes, planes * block.expansion, kernel_size=1, stride=stride, bias=False),
                BatchNorm2d(planes * block.expansion, momentum=BN_MOMENTUM),
            )

        layers = []
        layers.append(block(inplanes, planes, stride, downsample))
        inplanes = planes * block.expansion
        for i in range(1, blocks):
            layers.append(block(inplanes, planes))

        return nn.Sequential(*layers)

    def _make_stage(self, config_list, num_inchannels, multi_scale_output=True):
        num_modules = config_list[0]
        num_branches = config_list[1]
        num_blocks = config_list[2]
        num_channels = config_list[3]
        block = blocks_dict[config_list[4]]
        fuse_method = config_list[5]

        modules = []
        for i in range(num_modules):
            # multi_scale_output is only used last module
            if not multi_scale_output and i == num_modules - 1:
                reset_multi_scale_output = False
            else:
                reset_multi_scale_output = True
            modules.append(
                HighResolutionModule(
                    num_branches, block, num_blocks, num_inchannels, num_channels, fuse_method, reset_multi_scale_output
                )
            )
            num_inchannels = modules[-1].get_num_inchannels()

        return nn.Sequential(*modules), num_inchannels

    def forward(self, x):
        # h, w = x.size(2), x.size(3)
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.conv2(x)
        x = self.bn2(x)
        x = self.relu(x)
        x = self.layer1(x)

        x_list = []
        for i in range(2):
            if self.transition1[i] is not None:
                x_list.append(self.transition1[i](x))
            else:
                x_list.append(x)
        y_list = self.stage2(x_list)

        x_list = []
        for i in range(3):
            if self.transition2[i] is not None:
                x_list.append(self.transition2[i](y_list[-1]))
            else:
                x_list.append(y_list[i])
        y_list = self.stage3(x_list)

        x_list = []
        for i in range(4):
            if self.transition3[i] is not None:
                x_list.append(self.transition3[i](y_list[-1]))
            else:
                x_list.append(y_list[i])
        x = self.stage4(x_list)

        # Head Part
        height, width = x[0].size(2), x[0].size(3)
        x1 = F.interpolate(x[1], size=(height, width), mode="bilinear", align_corners=False)
        x2 = F.interpolate(x[2], size=(height, width), mode="bilinear", align_corners=False)
        x3 = F.interpolate(x[3], size=(height, width), mode="bilinear", align_corners=False)
        x = torch.cat([x[0], x1, x2, x3], 1)
        x = self.head(x)

        return x