Source code for flowvision.models.hrnet

"""
Modified from https://github.com/rwightman/pytorch-image-models/blob/master/timm/models/hrnet.py
"""
from typing import Callable, List, Optional

import oneflow as flow
import oneflow.nn as nn
import oneflow.nn.functional as F

from .registry import ModelCreator
from .utils import load_state_dict_from_url

_BN_MOMENTUM = 0.1

model_urls = {
    "hrnet_w18_small": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w18_small_v1.zip",
    "hrnet_w18_small_v2": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w18_small_v2.zip",
    "hrnet_w18": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w18.zip",
    "hrnet_w30": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w30.zip",
    "hrnet_w32": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w32.zip",
    "hrnet_w40": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w40.zip",
    "hrnet_w44": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w44.zip",
    "hrnet_w48": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w48.zip",
    "hrnet_w64": "https://oneflow-public.oss-cn-beijing.aliyuncs.com/model_zoo/flowvision/classification/HRNet/hrnet_w64.zip",
}


cfg_cls = dict(
    hrnet_w18_small=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(1,),
            NUM_CHANNELS=(32,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2),
            NUM_CHANNELS=(16, 32),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2, 2),
            NUM_CHANNELS=(16, 32, 64),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2, 2, 2),
            NUM_CHANNELS=(16, 32, 64, 128),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w18_small_v2=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(2,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2),
            NUM_CHANNELS=(18, 36),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2, 2),
            NUM_CHANNELS=(18, 36, 72),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=2,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(2, 2, 2, 2),
            NUM_CHANNELS=(18, 36, 72, 144),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w18=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(18, 36),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(18, 36, 72),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(18, 36, 72, 144),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w30=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(30, 60),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(30, 60, 120),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(30, 60, 120, 240),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w32=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(32, 64),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(32, 64, 128),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(32, 64, 128, 256),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w40=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(40, 80),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(40, 80, 160),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(40, 80, 160, 320),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w44=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(44, 88),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(44, 88, 176),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(44, 88, 176, 352),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w48=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(48, 96),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(48, 96, 192),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(48, 96, 192, 384),
            FUSE_METHOD="SUM",
        ),
    ),
    hrnet_w64=dict(
        STEM_WIDTH=64,
        STAGE1=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=1,
            BLOCK="BOTTLENECK",
            NUM_BLOCKS=(4,),
            NUM_CHANNELS=(64,),
            FUSE_METHOD="SUM",
        ),
        STAGE2=dict(
            NUM_MODULES=1,
            NUM_BRANCHES=2,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4),
            NUM_CHANNELS=(64, 128),
            FUSE_METHOD="SUM",
        ),
        STAGE3=dict(
            NUM_MODULES=4,
            NUM_BRANCHES=3,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4),
            NUM_CHANNELS=(64, 128, 256),
            FUSE_METHOD="SUM",
        ),
        STAGE4=dict(
            NUM_MODULES=3,
            NUM_BRANCHES=4,
            BLOCK="BASIC",
            NUM_BLOCKS=(4, 4, 4, 4),
            NUM_CHANNELS=(64, 128, 256, 512),
            FUSE_METHOD="SUM",
        ),
    ),
)


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


def conv1x1(in_planes: int, out_planes: int, stride: int = 1) -> nn.Conv2d:
    """1x1 convolution"""
    return nn.Conv2d(in_planes, out_planes, kernel_size=1, stride=stride, bias=False)


class BasicBlock(nn.Module):
    expansion: int = 1

    def __init__(
        self,
        inplanes: int,
        planes: int,
        stride: int = 1,
        downsample: Optional[nn.Module] = None,
        groups: int = 1,
        base_width: int = 64,
        dilation: int = 1,
        norm_layer: Optional[Callable[..., nn.Module]] = None,
    ) -> None:
        super(BasicBlock, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        if groups != 1 or base_width != 64:
            raise ValueError("BasicBlock only supports groups=1 and base_width=64")
        if dilation > 1:
            raise NotImplementedError("Dilation > 1 not supported in BasicBlock")
        # Both self.conv1 and self.downsample layers downsample the input when stride != 1
        self.conv1 = conv3x3(inplanes, planes, stride)
        self.bn1 = norm_layer(planes)
        self.relu = nn.ReLU()
        self.conv2 = conv3x3(planes, planes)
        self.bn2 = norm_layer(planes)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        identity = 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:
            identity = self.downsample(x)

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

        return out


class Bottleneck(nn.Module):
    expansion: int = 4

    def __init__(
        self,
        inplanes: int,
        planes: int,
        stride: int = 1,
        downsample: Optional[nn.Module] = None,
        groups: int = 1,
        base_width: int = 64,
        dilation: int = 1,
        norm_layer: Optional[Callable[..., nn.Module]] = None,
    ) -> None:
        super(Bottleneck, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        width = int(planes * (base_width / 64.0)) * groups
        # Both self.conv2 and self.downsample layers downsample the input when stride != 1
        self.conv1 = conv1x1(inplanes, width)
        self.bn1 = norm_layer(width)
        self.conv2 = conv3x3(width, width, stride, groups, dilation)
        self.bn2 = norm_layer(width)
        self.conv3 = conv1x1(width, planes * self.expansion)
        self.bn3 = norm_layer(planes * self.expansion)
        self.relu = nn.ReLU()
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        identity = 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:
            identity = self.downsample(x)

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

        return out


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

        self.num_in_chs = num_in_chs
        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.fuse_act = nn.ReLU(False)

    def _check_branches(
        self, num_branches, blocks, num_blocks, num_in_chs, num_channels
    ):
        error_msg = ""
        if num_branches != len(num_blocks):
            error_msg = "NUM_BRANCHES({}) <> NUM_BLOCKS({})".format(
                num_branches, len(num_blocks)
            )
        elif num_branches != len(num_channels):
            error_msg = "NUM_BRANCHES({}) <> NUM_CHANNELS({})".format(
                num_branches, len(num_channels)
            )
        elif num_branches != len(num_in_chs):
            error_msg = "NUM_BRANCHES({}) <> num_in_chs({})".format(
                num_branches, len(num_in_chs)
            )
        if 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_in_chs[branch_index]
            != num_channels[branch_index] * block.expansion
        ):
            downsample = nn.Sequential(
                nn.Conv2d(
                    self.num_in_chs[branch_index],
                    num_channels[branch_index] * block.expansion,
                    kernel_size=1,
                    stride=stride,
                    bias=False,
                ),
                nn.BatchNorm2d(
                    num_channels[branch_index] * block.expansion, momentum=_BN_MOMENTUM
                ),
            )

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

        num_branches = self.num_branches
        num_in_chs = self.num_in_chs
        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_in_chs[j], num_in_chs[i], 1, 1, 0, bias=False
                            ),
                            nn.BatchNorm2d(num_in_chs[i], momentum=_BN_MOMENTUM),
                            nn.Upsample(scale_factor=2 ** (j - i), mode="nearest"),
                        )
                    )
                elif j == i:
                    fuse_layer.append(nn.Identity())
                else:
                    conv3x3s = []
                    for k in range(i - j):
                        if k == i - j - 1:
                            num_outchannels_conv3x3 = num_in_chs[i]
                            conv3x3s.append(
                                nn.Sequential(
                                    nn.Conv2d(
                                        num_in_chs[j],
                                        num_outchannels_conv3x3,
                                        3,
                                        2,
                                        1,
                                        bias=False,
                                    ),
                                    nn.BatchNorm2d(
                                        num_outchannels_conv3x3, momentum=_BN_MOMENTUM
                                    ),
                                )
                            )
                        else:
                            num_outchannels_conv3x3 = num_in_chs[j]
                            conv3x3s.append(
                                nn.Sequential(
                                    nn.Conv2d(
                                        num_in_chs[j],
                                        num_outchannels_conv3x3,
                                        3,
                                        2,
                                        1,
                                        bias=False,
                                    ),
                                    nn.BatchNorm2d(
                                        num_outchannels_conv3x3, momentum=_BN_MOMENTUM
                                    ),
                                    nn.ReLU(False),
                                )
                            )
                    fuse_layer.append(nn.Sequential(*conv3x3s))
            fuse_layers.append(nn.ModuleList(fuse_layer))

        return nn.ModuleList(fuse_layers)

    def get_num_in_chs(self):
        return self.num_in_chs

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

        for i, branch in enumerate(self.branches):
            x[i] = branch(x[i])

        x_fuse = []
        for i, fuse_outer in enumerate(self.fuse_layers):
            y = x[0] if i == 0 else fuse_outer[0](x[0])
            for j in range(1, self.num_branches):
                if i == j:
                    y = y + x[j]
                else:
                    y = y + fuse_outer[j](x[j])
            x_fuse.append(self.fuse_act(y))

        return x_fuse


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


class HighResolutionNet(nn.Module):
    def __init__(
        self,
        cfg,
        in_chans=3,
        num_classes=1000,
        global_pool="avg",
        drop_rate=0.0,
        head="classification",
    ):
        super(HighResolutionNet, self).__init__()
        self.num_classes = num_classes
        self.drop_rate = drop_rate

        stem_width = cfg["STEM_WIDTH"]
        self.conv1 = nn.Conv2d(
            in_chans, stem_width, kernel_size=3, stride=2, padding=1, bias=False
        )
        self.bn1 = nn.BatchNorm2d(stem_width, momentum=_BN_MOMENTUM)
        self.act1 = nn.ReLU(inplace=True)
        self.conv2 = nn.Conv2d(
            stem_width, 64, kernel_size=3, stride=2, padding=1, bias=False
        )
        self.bn2 = nn.BatchNorm2d(64, momentum=_BN_MOMENTUM)
        self.act2 = nn.ReLU(inplace=True)

        self.stage1_cfg = cfg["STAGE1"]
        num_channels = self.stage1_cfg["NUM_CHANNELS"][0]
        block = blocks_dict[self.stage1_cfg["BLOCK"]]
        num_blocks = self.stage1_cfg["NUM_BLOCKS"][0]
        self.layer1 = self._make_layer(block, 64, num_channels, num_blocks)
        stage1_out_channel = block.expansion * num_channels

        self.stage2_cfg = cfg["STAGE2"]
        num_channels = self.stage2_cfg["NUM_CHANNELS"]
        block = blocks_dict[self.stage2_cfg["BLOCK"]]
        num_channels = [
            num_channels[i] * block.expansion for i in range(len(num_channels))
        ]
        self.transition1 = self._make_transition_layer(
            [stage1_out_channel], num_channels
        )
        self.stage2, pre_stage_channels = self._make_stage(
            self.stage2_cfg, num_channels
        )

        self.stage3_cfg = cfg["STAGE3"]
        num_channels = self.stage3_cfg["NUM_CHANNELS"]
        block = blocks_dict[self.stage3_cfg["BLOCK"]]
        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)
        self.stage3, pre_stage_channels = self._make_stage(
            self.stage3_cfg, num_channels
        )

        self.stage4_cfg = cfg["STAGE4"]
        num_channels = self.stage4_cfg["NUM_CHANNELS"]
        block = blocks_dict[self.stage4_cfg["BLOCK"]]
        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)
        self.stage4, pre_stage_channels = self._make_stage(
            self.stage4_cfg, num_channels, multi_scale_output=True
        )

        self.head = head
        self.head_channels = None  # set if _make_head called
        if head == "classification":
            # Classification Head
            self.num_features = 2048
            (
                self.incre_modules,
                self.downsamp_modules,
                self.final_layer,
            ) = self._make_head(pre_stage_channels)
            self.global_pool = nn.Sequential(nn.AdaptiveAvgPool2d(1), nn.Flatten(1))
            self.classifier = nn.Linear(self.num_features, self.num_classes, bias=True)
        elif head == "incre":
            self.num_features = 2048
            self.incre_modules, _, _ = self._make_head(pre_stage_channels, True)
        else:
            self.incre_modules = None
            self.num_features = 256

        curr_stride = 2
        # module names aren't actually valid here, hook or FeatureNet based extraction would not work
        self.feature_info = [dict(num_chs=64, reduction=curr_stride, module="stem")]
        for i, c in enumerate(
            self.head_channels if self.head_channels else num_channels
        ):
            curr_stride *= 2
            c = c * 4 if self.head_channels else c  # head block expansion factor of 4
            self.feature_info += [
                dict(num_chs=c, reduction=curr_stride, module=f"stage{i + 1}")
            ]

        self.init_weights()

    def _make_head(self, pre_stage_channels, incre_only=False):
        head_block = Bottleneck
        self.head_channels = [32, 64, 128, 256]

        # Increasing the #channels on each resolution
        # from C, 2C, 4C, 8C to 128, 256, 512, 1024
        incre_modules = []
        for i, channels in enumerate(pre_stage_channels):
            incre_modules.append(
                self._make_layer(
                    head_block, channels, self.head_channels[i], 1, stride=1
                )
            )
        incre_modules = nn.ModuleList(incre_modules)
        if incre_only:
            return incre_modules, None, None

        # downsampling modules
        downsamp_modules = []
        for i in range(len(pre_stage_channels) - 1):
            in_channels = self.head_channels[i] * head_block.expansion
            out_channels = self.head_channels[i + 1] * head_block.expansion
            downsamp_module = nn.Sequential(
                nn.Conv2d(
                    in_channels=in_channels,
                    out_channels=out_channels,
                    kernel_size=3,
                    stride=2,
                    padding=1,
                ),
                nn.BatchNorm2d(out_channels, momentum=_BN_MOMENTUM),
                nn.ReLU(inplace=True),
            )
            downsamp_modules.append(downsamp_module)
        downsamp_modules = nn.ModuleList(downsamp_modules)

        final_layer = nn.Sequential(
            nn.Conv2d(
                in_channels=self.head_channels[3] * head_block.expansion,
                out_channels=self.num_features,
                kernel_size=1,
                stride=1,
                padding=0,
            ),
            nn.BatchNorm2d(self.num_features, momentum=_BN_MOMENTUM),
            nn.ReLU(inplace=True),
        )

        return incre_modules, downsamp_modules, final_layer

    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,
                            ),
                            nn.BatchNorm2d(
                                num_channels_cur_layer[i], momentum=_BN_MOMENTUM
                            ),
                            nn.ReLU(inplace=True),
                        )
                    )
                else:
                    transition_layers.append(nn.Identity())
            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),
                            nn.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,
                ),
                nn.BatchNorm2d(planes * block.expansion, momentum=_BN_MOMENTUM),
            )

        layers = [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, layer_config, num_in_chs, multi_scale_output=True):
        num_modules = layer_config["NUM_MODULES"]
        num_branches = layer_config["NUM_BRANCHES"]
        num_blocks = layer_config["NUM_BLOCKS"]
        num_channels = layer_config["NUM_CHANNELS"]
        block = blocks_dict[layer_config["BLOCK"]]
        fuse_method = layer_config["FUSE_METHOD"]

        modules = []
        for i in range(num_modules):
            # multi_scale_output is only used last module
            reset_multi_scale_output = multi_scale_output or i < num_modules - 1
            modules.append(
                HighResolutionModule(
                    num_branches,
                    block,
                    num_blocks,
                    num_in_chs,
                    num_channels,
                    fuse_method,
                    reset_multi_scale_output,
                )
            )
            num_in_chs = modules[-1].get_num_in_chs()

        return nn.Sequential(*modules), num_in_chs

    def init_weights(self):
        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode="fan_out", nonlinearity="relu")
            elif isinstance(m, nn.BatchNorm2d):
                nn.init.constant_(m.weight, 1)
                nn.init.constant_(m.bias, 0)

    def group_matcher(self, coarse=False):
        matcher = dict(
            stem=r"^conv[12]|bn[12]",
            blocks=r"^(?:layer|stage|transition)(\d+)"
            if coarse
            else [
                (r"^layer(\d+)\.(\d+)", None),
                (r"^stage(\d+)\.(\d+)", None),
                (r"^transition(\d+)", (99999,)),
            ],
        )
        return matcher

    def set_grad_checkpointing(self, enable=True):
        assert not enable, "gradient checkpointing not supported"

    def get_classifier(self):
        return self.classifier

    def reset_classifier(self, num_classes, global_pool="avg"):
        self.num_classes = num_classes
        self.global_pool = nn.Sequential(nn.AdaptiveAvgPool2d(1), nn.Flatten(1))
        self.classifier = nn.Linear(self.num_features, self.num_classes, bias=True)

    def stages(self, x) -> List[flow.Tensor]:
        x = self.layer1(x)

        xl = [t(x) for i, t in enumerate(self.transition1)]
        yl = self.stage2(xl)

        xl = [
            t(yl[-1]) if not isinstance(t, nn.Identity) else yl[i]
            for i, t in enumerate(self.transition2)
        ]
        yl = self.stage3(xl)

        xl = [
            t(yl[-1]) if not isinstance(t, nn.Identity) else yl[i]
            for i, t in enumerate(self.transition3)
        ]
        yl = self.stage4(xl)
        return yl

    def forward_features(self, x):
        # Stem
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.act1(x)
        x = self.conv2(x)
        x = self.bn2(x)
        x = self.act2(x)

        # Stages
        yl = self.stages(x)
        if self.incre_modules is None or self.downsamp_modules is None:
            return yl
        y = self.incre_modules[0](yl[0])
        for i, down in enumerate(self.downsamp_modules):
            y = self.incre_modules[i + 1](yl[i + 1]) + down(y)
        y = self.final_layer(y)
        return y

    def forward_head(self, x, pre_logits: bool = False):
        # Classification Head
        x = self.global_pool(x)
        if self.drop_rate > 0.0:
            x = F.dropout(x, p=self.drop_rate, training=self.training)
        return x if pre_logits else self.classifier(x)

    def forward(self, x):
        y = self.forward_features(x)
        x = self.forward_head(y)
        return x


[docs]@ModelCreator.register_model def hrnet_w18_small(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w18-small 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w18-small 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w18_small = flowvision.models.hrnet_w18_small(pretrained=False, progress=True) """ arch = "hrnet_w18_small" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w18_small_v2(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w18-small-v2 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w18-small-v2 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w18_small_v2 = flowvision.models.hrnet_w18_small_v2(pretrained=False, progress=True) """ arch = "hrnet_w18_small_v2" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w18(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w18 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w18 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w18 = flowvision.models.hrnet_w18(pretrained=False, progress=True) """ arch = "hrnet_w18" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w30(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w30 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w30 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w30 = flowvision.models.hrnet_w30(pretrained=False, progress=True) """ arch = "hrnet_w30" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w32(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w32 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w32 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w32 = flowvision.models.hrnet_w32(pretrained=False, progress=True) """ arch = "hrnet_w32" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w40(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w40 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w40 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w40 = flowvision.models.hrnet_w40(pretrained=False, progress=True) """ arch = "hrnet_w40" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w44(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w44 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w44 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w44 = flowvision.models.hrnet_w44(pretrained=False, progress=True) """ arch = "hrnet_w44" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w48(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w48 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w48 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w48 = flowvision.models.hrnet_w48(pretrained=False, progress=True) """ arch = "hrnet_w48" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model
[docs]@ModelCreator.register_model def hrnet_w64(pretrained: bool = False, progress: bool = True, **kwargs): """ Constructs HRNet-w64 224x224 model pretrained on ImageNet-1k. .. note:: HRNet-w64 224x224 model from `"Deep High-Resolution Representation Learning for Visual Recognition" <https://arxiv.org/pdf/1908.07919>`_. Args: pretrained (bool): Whether to download the pre-trained model on ImageNet. Default: ``False`` progress (bool): If True, displays a progress bar of the download to stderr. Default: ``True`` For example: .. code-block:: python >>> import flowvision >>> hrnet_w64 = flowvision.models.hrnet_w64(pretrained=False, progress=True) """ arch = "hrnet_w64" model = HighResolutionNet(cfg=cfg_cls[arch], **kwargs) if pretrained: state_dict = load_state_dict_from_url(model_urls[arch], progress=progress) model.load_state_dict(state_dict) return model