Add densepose converters

densepose/converters/__init__.py

@@ -0,0 +1,15 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from .hflip import HFlipConverter
+from .to_mask import ToMaskConverter
+from .to_chart_result import ToChartResultConverter, ToChartResultConverterWithConfidences
+from .segm_to_mask import (
+    predictor_output_with_fine_and_coarse_segm_to_mask,
+    predictor_output_with_coarse_segm_to_mask,
+    resample_fine_and_coarse_segm_to_bbox,
+)
+from .chart_output_to_chart_result import (
+    densepose_chart_predictor_output_to_result,
+    densepose_chart_predictor_output_to_result_with_confidences,
+)
+from .chart_output_hflip import densepose_chart_predictor_output_hflip

densepose/converters/base.py

@@ -0,0 +1,93 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any, Tuple, Type
+import torch
+
+
+class BaseConverter:
+    """
+    Converter base class to be reused by various converters.
+    Converter allows one to convert data from various source types to a particular
+    destination type. Each source type needs to register its converter. The
+    registration for each source type is valid for all descendants of that type.
+    """
+
+    @classmethod
+    def register(cls, from_type: Type, converter: Any = None):
+        """
+        Registers a converter for the specified type.
+        Can be used as a decorator (if converter is None), or called as a method.
+
+        Args:
+            from_type (type): type to register the converter for;
+                all instances of this type will use the same converter
+            converter (callable): converter to be registered for the given
+                type; if None, this method is assumed to be a decorator for the converter
+        """
+
+        if converter is not None:
+            cls._do_register(from_type, converter)
+
+        def wrapper(converter: Any) -> Any:
+            cls._do_register(from_type, converter)
+            return converter
+
+        return wrapper
+
+    @classmethod
+    def _do_register(cls, from_type: Type, converter: Any):
+        cls.registry[from_type] = converter  # pyre-ignore[16]
+
+    @classmethod
+    def _lookup_converter(cls, from_type: Type) -> Any:
+        """
+        Perform recursive lookup for the given type
+        to find registered converter. If a converter was found for some base
+        class, it gets registered for this class to save on further lookups.
+
+        Args:
+            from_type: type for which to find a converter
+        Return:
+            callable or None - registered converter or None
+                if no suitable entry was found in the registry
+        """
+        if from_type in cls.registry:  # pyre-ignore[16]
+            return cls.registry[from_type]
+        for base in from_type.__bases__:
+            converter = cls._lookup_converter(base)
+            if converter is not None:
+                cls._do_register(from_type, converter)
+                return converter
+        return None
+
+    @classmethod
+    def convert(cls, instance: Any, *args, **kwargs):
+        """
+        Convert an instance to the destination type using some registered
+        converter. Does recursive lookup for base classes, so there's no need
+        for explicit registration for derived classes.
+
+        Args:
+            instance: source instance to convert to the destination type
+        Return:
+            An instance of the destination type obtained from the source instance
+            Raises KeyError, if no suitable converter found
+        """
+        instance_type = type(instance)
+        converter = cls._lookup_converter(instance_type)
+        if converter is None:
+            if cls.dst_type is None:  # pyre-ignore[16]
+                output_type_str = "itself"
+            else:
+                output_type_str = cls.dst_type
+            raise KeyError(f"Could not find converter from {instance_type} to {output_type_str}")
+        return converter(instance, *args, **kwargs)
+
+
+IntTupleBox = Tuple[int, int, int, int]
+
+
+def make_int_box(box: torch.Tensor) -> IntTupleBox:
+    int_box = [0, 0, 0, 0]
+    int_box[0], int_box[1], int_box[2], int_box[3] = tuple(box.long().tolist())
+    return int_box[0], int_box[1], int_box[2], int_box[3]

densepose/converters/builtin.py

@@ -0,0 +1,31 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from ..structures import DensePoseChartPredictorOutput, DensePoseEmbeddingPredictorOutput
+from . import (
+    HFlipConverter,
+    ToChartResultConverter,
+    ToChartResultConverterWithConfidences,
+    ToMaskConverter,
+    densepose_chart_predictor_output_hflip,
+    densepose_chart_predictor_output_to_result,
+    densepose_chart_predictor_output_to_result_with_confidences,
+    predictor_output_with_coarse_segm_to_mask,
+    predictor_output_with_fine_and_coarse_segm_to_mask,
+)
+
+ToMaskConverter.register(
+    DensePoseChartPredictorOutput, predictor_output_with_fine_and_coarse_segm_to_mask
+)
+ToMaskConverter.register(
+    DensePoseEmbeddingPredictorOutput, predictor_output_with_coarse_segm_to_mask
+)
+
+ToChartResultConverter.register(
+    DensePoseChartPredictorOutput, densepose_chart_predictor_output_to_result
+)
+
+ToChartResultConverterWithConfidences.register(
+    DensePoseChartPredictorOutput, densepose_chart_predictor_output_to_result_with_confidences
+)
+
+HFlipConverter.register(DensePoseChartPredictorOutput, densepose_chart_predictor_output_hflip)

densepose/converters/chart_output_hflip.py

@@ -0,0 +1,71 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+from dataclasses import fields
+import torch
+
+from densepose.structures import DensePoseChartPredictorOutput, DensePoseTransformData
+
+
+def densepose_chart_predictor_output_hflip(
+    densepose_predictor_output: DensePoseChartPredictorOutput,
+    transform_data: DensePoseTransformData,
+) -> DensePoseChartPredictorOutput:
+    """
+    Change  to take into account a Horizontal flip.
+    """
+    if len(densepose_predictor_output) > 0:
+
+        PredictorOutput = type(densepose_predictor_output)
+        output_dict = {}
+
+        for field in fields(densepose_predictor_output):
+            field_value = getattr(densepose_predictor_output, field.name)
+            # flip tensors
+            if isinstance(field_value, torch.Tensor):
+                setattr(densepose_predictor_output, field.name, torch.flip(field_value, [3]))
+
+        densepose_predictor_output = _flip_iuv_semantics_tensor(
+            densepose_predictor_output, transform_data
+        )
+        densepose_predictor_output = _flip_segm_semantics_tensor(
+            densepose_predictor_output, transform_data
+        )
+
+        for field in fields(densepose_predictor_output):
+            output_dict[field.name] = getattr(densepose_predictor_output, field.name)
+
+        return PredictorOutput(**output_dict)
+    else:
+        return densepose_predictor_output
+
+
+def _flip_iuv_semantics_tensor(
+    densepose_predictor_output: DensePoseChartPredictorOutput,
+    dp_transform_data: DensePoseTransformData,
+) -> DensePoseChartPredictorOutput:
+    point_label_symmetries = dp_transform_data.point_label_symmetries
+    uv_symmetries = dp_transform_data.uv_symmetries
+
+    N, C, H, W = densepose_predictor_output.u.shape
+    u_loc = (densepose_predictor_output.u[:, 1:, :, :].clamp(0, 1) * 255).long()
+    v_loc = (densepose_predictor_output.v[:, 1:, :, :].clamp(0, 1) * 255).long()
+    Iindex = torch.arange(C - 1, device=densepose_predictor_output.u.device)[
+        None, :, None, None
+    ].expand(N, C - 1, H, W)
+    densepose_predictor_output.u[:, 1:, :, :] = uv_symmetries["U_transforms"][Iindex, v_loc, u_loc]
+    densepose_predictor_output.v[:, 1:, :, :] = uv_symmetries["V_transforms"][Iindex, v_loc, u_loc]
+
+    for el in ["fine_segm", "u", "v"]:
+        densepose_predictor_output.__dict__[el] = densepose_predictor_output.__dict__[el][
+            :, point_label_symmetries, :, :
+        ]
+    return densepose_predictor_output
+
+
+def _flip_segm_semantics_tensor(
+    densepose_predictor_output: DensePoseChartPredictorOutput, dp_transform_data
+):
+    if densepose_predictor_output.coarse_segm.shape[1] > 2:
+        densepose_predictor_output.coarse_segm = densepose_predictor_output.coarse_segm[
+            :, dp_transform_data.mask_label_symmetries, :, :
+        ]
+    return densepose_predictor_output

densepose/converters/chart_output_to_chart_result.py

@@ -0,0 +1,188 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Dict
+import torch
+from torch.nn import functional as F
+
+from detectron2.structures.boxes import Boxes, BoxMode
+
+from ..structures import (
+    DensePoseChartPredictorOutput,
+    DensePoseChartResult,
+    DensePoseChartResultWithConfidences,
+)
+from . import resample_fine_and_coarse_segm_to_bbox
+from .base import IntTupleBox, make_int_box
+
+
+def resample_uv_tensors_to_bbox(
+    u: torch.Tensor,
+    v: torch.Tensor,
+    labels: torch.Tensor,
+    box_xywh_abs: IntTupleBox,
+) -> torch.Tensor:
+    """
+    Resamples U and V coordinate estimates for the given bounding box
+
+    Args:
+        u (tensor [1, C, H, W] of float): U coordinates
+        v (tensor [1, C, H, W] of float): V coordinates
+        labels (tensor [H, W] of long): labels obtained by resampling segmentation
+            outputs for the given bounding box
+        box_xywh_abs (tuple of 4 int): bounding box that corresponds to predictor outputs
+    Return:
+       Resampled U and V coordinates - a tensor [2, H, W] of float
+    """
+    x, y, w, h = box_xywh_abs
+    w = max(int(w), 1)
+    h = max(int(h), 1)
+    u_bbox = F.interpolate(u, (h, w), mode="bilinear", align_corners=False)
+    v_bbox = F.interpolate(v, (h, w), mode="bilinear", align_corners=False)
+    uv = torch.zeros([2, h, w], dtype=torch.float32, device=u.device)
+    for part_id in range(1, u_bbox.size(1)):
+        uv[0][labels == part_id] = u_bbox[0, part_id][labels == part_id]
+        uv[1][labels == part_id] = v_bbox[0, part_id][labels == part_id]
+    return uv
+
+
+def resample_uv_to_bbox(
+    predictor_output: DensePoseChartPredictorOutput,
+    labels: torch.Tensor,
+    box_xywh_abs: IntTupleBox,
+) -> torch.Tensor:
+    """
+    Resamples U and V coordinate estimates for the given bounding box
+
+    Args:
+        predictor_output (DensePoseChartPredictorOutput): DensePose predictor
+            output to be resampled
+        labels (tensor [H, W] of long): labels obtained by resampling segmentation
+            outputs for the given bounding box
+        box_xywh_abs (tuple of 4 int): bounding box that corresponds to predictor outputs
+    Return:
+       Resampled U and V coordinates - a tensor [2, H, W] of float
+    """
+    return resample_uv_tensors_to_bbox(
+        predictor_output.u,
+        predictor_output.v,
+        labels,
+        box_xywh_abs,
+    )
+
+
+def densepose_chart_predictor_output_to_result(
+    predictor_output: DensePoseChartPredictorOutput, boxes: Boxes
+) -> DensePoseChartResult:
+    """
+    Convert densepose chart predictor outputs to results
+
+    Args:
+        predictor_output (DensePoseChartPredictorOutput): DensePose predictor
+            output to be converted to results, must contain only 1 output
+        boxes (Boxes): bounding box that corresponds to the predictor output,
+            must contain only 1 bounding box
+    Return:
+       DensePose chart-based result (DensePoseChartResult)
+    """
+    assert len(predictor_output) == 1 and len(boxes) == 1, (
+        f"Predictor output to result conversion can operate only single outputs"
+        f", got {len(predictor_output)} predictor outputs and {len(boxes)} boxes"
+    )
+
+    boxes_xyxy_abs = boxes.tensor.clone()
+    boxes_xywh_abs = BoxMode.convert(boxes_xyxy_abs, BoxMode.XYXY_ABS, BoxMode.XYWH_ABS)
+    box_xywh = make_int_box(boxes_xywh_abs[0])
+
+    labels = resample_fine_and_coarse_segm_to_bbox(predictor_output, box_xywh).squeeze(0)
+    uv = resample_uv_to_bbox(predictor_output, labels, box_xywh)
+    return DensePoseChartResult(labels=labels, uv=uv)
+
+
+def resample_confidences_to_bbox(
+    predictor_output: DensePoseChartPredictorOutput,
+    labels: torch.Tensor,
+    box_xywh_abs: IntTupleBox,
+) -> Dict[str, torch.Tensor]:
+    """
+    Resamples confidences for the given bounding box
+
+    Args:
+        predictor_output (DensePoseChartPredictorOutput): DensePose predictor
+            output to be resampled
+        labels (tensor [H, W] of long): labels obtained by resampling segmentation
+            outputs for the given bounding box
+        box_xywh_abs (tuple of 4 int): bounding box that corresponds to predictor outputs
+    Return:
+       Resampled confidences - a dict of [H, W] tensors of float
+    """
+
+    x, y, w, h = box_xywh_abs
+    w = max(int(w), 1)
+    h = max(int(h), 1)
+
+    confidence_names = [
+        "sigma_1",
+        "sigma_2",
+        "kappa_u",
+        "kappa_v",
+        "fine_segm_confidence",
+        "coarse_segm_confidence",
+    ]
+    confidence_results = {key: None for key in confidence_names}
+    confidence_names = [
+        key for key in confidence_names if getattr(predictor_output, key) is not None
+    ]
+    confidence_base = torch.zeros([h, w], dtype=torch.float32, device=predictor_output.u.device)
+
+    # assign data from channels that correspond to the labels
+    for key in confidence_names:
+        resampled_confidence = F.interpolate(
+            getattr(predictor_output, key),
+            (h, w),
+            mode="bilinear",
+            align_corners=False,
+        )
+        result = confidence_base.clone()
+        for part_id in range(1, predictor_output.u.size(1)):
+            if resampled_confidence.size(1) != predictor_output.u.size(1):
+                # confidence is not part-based, don't try to fill it part by part
+                continue
+            result[labels == part_id] = resampled_confidence[0, part_id][labels == part_id]
+
+        if resampled_confidence.size(1) != predictor_output.u.size(1):
+            # confidence is not part-based, fill the data with the first channel
+            # (targeted for segmentation confidences that have only 1 channel)
+            result = resampled_confidence[0, 0]
+
+        confidence_results[key] = result
+
+    return confidence_results  # pyre-ignore[7]
+
+
+def densepose_chart_predictor_output_to_result_with_confidences(
+    predictor_output: DensePoseChartPredictorOutput, boxes: Boxes
+) -> DensePoseChartResultWithConfidences:
+    """
+    Convert densepose chart predictor outputs to results
+
+    Args:
+        predictor_output (DensePoseChartPredictorOutput): DensePose predictor
+            output with confidences to be converted to results, must contain only 1 output
+        boxes (Boxes): bounding box that corresponds to the predictor output,
+            must contain only 1 bounding box
+    Return:
+       DensePose chart-based result with confidences (DensePoseChartResultWithConfidences)
+    """
+    assert len(predictor_output) == 1 and len(boxes) == 1, (
+        f"Predictor output to result conversion can operate only single outputs"
+        f", got {len(predictor_output)} predictor outputs and {len(boxes)} boxes"
+    )
+
+    boxes_xyxy_abs = boxes.tensor.clone()
+    boxes_xywh_abs = BoxMode.convert(boxes_xyxy_abs, BoxMode.XYXY_ABS, BoxMode.XYWH_ABS)
+    box_xywh = make_int_box(boxes_xywh_abs[0])
+
+    labels = resample_fine_and_coarse_segm_to_bbox(predictor_output, box_xywh).squeeze(0)
+    uv = resample_uv_to_bbox(predictor_output, labels, box_xywh)
+    confidences = resample_confidences_to_bbox(predictor_output, labels, box_xywh)
+    return DensePoseChartResultWithConfidences(labels=labels, uv=uv, **confidences)

densepose/converters/hflip.py

@@ -0,0 +1,34 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any
+
+from .base import BaseConverter
+
+
+class HFlipConverter(BaseConverter):
+    """
+    Converts various DensePose predictor outputs to DensePose results.
+    Each DensePose predictor output type has to register its convertion strategy.
+    """
+
+    registry = {}
+    dst_type = None
+
+    @classmethod
+    # pyre-fixme[14]: `convert` overrides method defined in `BaseConverter`
+    #  inconsistently.
+    def convert(cls, predictor_outputs: Any, transform_data: Any, *args, **kwargs):
+        """
+        Performs an horizontal flip on DensePose predictor outputs.
+        Does recursive lookup for base classes, so there's no need
+        for explicit registration for derived classes.
+
+        Args:
+            predictor_outputs: DensePose predictor output to be converted to BitMasks
+            transform_data: Anything useful for the flip
+        Return:
+            An instance of the same type as predictor_outputs
+        """
+        return super(HFlipConverter, cls).convert(
+            predictor_outputs, transform_data, *args, **kwargs
+        )

densepose/converters/segm_to_mask.py

@@ -0,0 +1,150 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any
+import torch
+from torch.nn import functional as F
+
+from detectron2.structures import BitMasks, Boxes, BoxMode
+
+from .base import IntTupleBox, make_int_box
+from .to_mask import ImageSizeType
+
+
+def resample_coarse_segm_tensor_to_bbox(coarse_segm: torch.Tensor, box_xywh_abs: IntTupleBox):
+    """
+    Resample coarse segmentation tensor to the given
+    bounding box and derive labels for each pixel of the bounding box
+
+    Args:
+        coarse_segm: float tensor of shape [1, K, Hout, Wout]
+        box_xywh_abs (tuple of 4 int): bounding box given by its upper-left
+            corner coordinates, width (W) and height (H)
+    Return:
+        Labels for each pixel of the bounding box, a long tensor of size [1, H, W]
+    """
+    x, y, w, h = box_xywh_abs
+    w = max(int(w), 1)
+    h = max(int(h), 1)
+    labels = F.interpolate(coarse_segm, (h, w), mode="bilinear", align_corners=False).argmax(dim=1)
+    return labels
+
+
+def resample_fine_and_coarse_segm_tensors_to_bbox(
+    fine_segm: torch.Tensor, coarse_segm: torch.Tensor, box_xywh_abs: IntTupleBox
+):
+    """
+    Resample fine and coarse segmentation tensors to the given
+    bounding box and derive labels for each pixel of the bounding box
+
+    Args:
+        fine_segm: float tensor of shape [1, C, Hout, Wout]
+        coarse_segm: float tensor of shape [1, K, Hout, Wout]
+        box_xywh_abs (tuple of 4 int): bounding box given by its upper-left
+            corner coordinates, width (W) and height (H)
+    Return:
+        Labels for each pixel of the bounding box, a long tensor of size [1, H, W]
+    """
+    x, y, w, h = box_xywh_abs
+    w = max(int(w), 1)
+    h = max(int(h), 1)
+    # coarse segmentation
+    coarse_segm_bbox = F.interpolate(
+        coarse_segm,
+        (h, w),
+        mode="bilinear",
+        align_corners=False,
+    ).argmax(dim=1)
+    # combined coarse and fine segmentation
+    labels = (
+        F.interpolate(fine_segm, (h, w), mode="bilinear", align_corners=False).argmax(dim=1)
+        * (coarse_segm_bbox > 0).long()
+    )
+    return labels
+
+
+def resample_fine_and_coarse_segm_to_bbox(predictor_output: Any, box_xywh_abs: IntTupleBox):
+    """
+    Resample fine and coarse segmentation outputs from a predictor to the given
+    bounding box and derive labels for each pixel of the bounding box
+
+    Args:
+        predictor_output: DensePose predictor output that contains segmentation
+            results to be resampled
+        box_xywh_abs (tuple of 4 int): bounding box given by its upper-left
+            corner coordinates, width (W) and height (H)
+    Return:
+        Labels for each pixel of the bounding box, a long tensor of size [1, H, W]
+    """
+    return resample_fine_and_coarse_segm_tensors_to_bbox(
+        predictor_output.fine_segm,
+        predictor_output.coarse_segm,
+        box_xywh_abs,
+    )
+
+
+def predictor_output_with_coarse_segm_to_mask(
+    predictor_output: Any, boxes: Boxes, image_size_hw: ImageSizeType
+) -> BitMasks:
+    """
+    Convert predictor output with coarse and fine segmentation to a mask.
+    Assumes that predictor output has the following attributes:
+     - coarse_segm (tensor of size [N, D, H, W]): coarse segmentation
+         unnormalized scores for N instances; D is the number of coarse
+         segmentation labels, H and W is the resolution of the estimate
+
+    Args:
+        predictor_output: DensePose predictor output to be converted to mask
+        boxes (Boxes): bounding boxes that correspond to the DensePose
+            predictor outputs
+        image_size_hw (tuple [int, int]): image height Himg and width Wimg
+    Return:
+        BitMasks that contain a bool tensor of size [N, Himg, Wimg] with
+        a mask of the size of the image for each instance
+    """
+    H, W = image_size_hw
+    boxes_xyxy_abs = boxes.tensor.clone()
+    boxes_xywh_abs = BoxMode.convert(boxes_xyxy_abs, BoxMode.XYXY_ABS, BoxMode.XYWH_ABS)
+    N = len(boxes_xywh_abs)
+    masks = torch.zeros((N, H, W), dtype=torch.bool, device=boxes.tensor.device)
+    for i in range(len(boxes_xywh_abs)):
+        box_xywh = make_int_box(boxes_xywh_abs[i])
+        box_mask = resample_coarse_segm_tensor_to_bbox(predictor_output[i].coarse_segm, box_xywh)
+        x, y, w, h = box_xywh
+        masks[i, y : y + h, x : x + w] = box_mask
+
+    return BitMasks(masks)
+
+
+def predictor_output_with_fine_and_coarse_segm_to_mask(
+    predictor_output: Any, boxes: Boxes, image_size_hw: ImageSizeType
+) -> BitMasks:
+    """
+    Convert predictor output with coarse and fine segmentation to a mask.
+    Assumes that predictor output has the following attributes:
+     - coarse_segm (tensor of size [N, D, H, W]): coarse segmentation
+         unnormalized scores for N instances; D is the number of coarse
+         segmentation labels, H and W is the resolution of the estimate
+     - fine_segm (tensor of size [N, C, H, W]): fine segmentation
+         unnormalized scores for N instances; C is the number of fine
+         segmentation labels, H and W is the resolution of the estimate
+
+    Args:
+        predictor_output: DensePose predictor output to be converted to mask
+        boxes (Boxes): bounding boxes that correspond to the DensePose
+            predictor outputs
+        image_size_hw (tuple [int, int]): image height Himg and width Wimg
+    Return:
+        BitMasks that contain a bool tensor of size [N, Himg, Wimg] with
+        a mask of the size of the image for each instance
+    """
+    H, W = image_size_hw
+    boxes_xyxy_abs = boxes.tensor.clone()
+    boxes_xywh_abs = BoxMode.convert(boxes_xyxy_abs, BoxMode.XYXY_ABS, BoxMode.XYWH_ABS)
+    N = len(boxes_xywh_abs)
+    masks = torch.zeros((N, H, W), dtype=torch.bool, device=boxes.tensor.device)
+    for i in range(len(boxes_xywh_abs)):
+        box_xywh = make_int_box(boxes_xywh_abs[i])
+        labels_i = resample_fine_and_coarse_segm_to_bbox(predictor_output[i], box_xywh)
+        x, y, w, h = box_xywh
+        masks[i, y : y + h, x : x + w] = labels_i > 0
+    return BitMasks(masks)

densepose/converters/to_chart_result.py

@@ -0,0 +1,70 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any
+
+from detectron2.structures import Boxes
+
+from ..structures import DensePoseChartResult, DensePoseChartResultWithConfidences
+from .base import BaseConverter
+
+
+class ToChartResultConverter(BaseConverter):
+    """
+    Converts various DensePose predictor outputs to DensePose results.
+    Each DensePose predictor output type has to register its convertion strategy.
+    """
+
+    registry = {}
+    dst_type = DensePoseChartResult
+
+    @classmethod
+    # pyre-fixme[14]: `convert` overrides method defined in `BaseConverter`
+    #  inconsistently.
+    def convert(cls, predictor_outputs: Any, boxes: Boxes, *args, **kwargs) -> DensePoseChartResult:
+        """
+        Convert DensePose predictor outputs to DensePoseResult using some registered
+        converter. Does recursive lookup for base classes, so there's no need
+        for explicit registration for derived classes.
+
+        Args:
+            densepose_predictor_outputs: DensePose predictor output to be
+                converted to BitMasks
+            boxes (Boxes): bounding boxes that correspond to the DensePose
+                predictor outputs
+        Return:
+            An instance of DensePoseResult. If no suitable converter was found, raises KeyError
+        """
+        return super(ToChartResultConverter, cls).convert(predictor_outputs, boxes, *args, **kwargs)
+
+
+class ToChartResultConverterWithConfidences(BaseConverter):
+    """
+    Converts various DensePose predictor outputs to DensePose results.
+    Each DensePose predictor output type has to register its convertion strategy.
+    """
+
+    registry = {}
+    dst_type = DensePoseChartResultWithConfidences
+
+    @classmethod
+    # pyre-fixme[14]: `convert` overrides method defined in `BaseConverter`
+    #  inconsistently.
+    def convert(
+        cls, predictor_outputs: Any, boxes: Boxes, *args, **kwargs
+    ) -> DensePoseChartResultWithConfidences:
+        """
+        Convert DensePose predictor outputs to DensePoseResult with confidences
+        using some registered converter. Does recursive lookup for base classes,
+        so there's no need for explicit registration for derived classes.
+
+        Args:
+            densepose_predictor_outputs: DensePose predictor output with confidences
+                to be converted to BitMasks
+            boxes (Boxes): bounding boxes that correspond to the DensePose
+                predictor outputs
+        Return:
+            An instance of DensePoseResult. If no suitable converter was found, raises KeyError
+        """
+        return super(ToChartResultConverterWithConfidences, cls).convert(
+            predictor_outputs, boxes, *args, **kwargs
+        )

densepose/converters/to_mask.py

@@ -0,0 +1,49 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any, Tuple
+
+from detectron2.structures import BitMasks, Boxes
+
+from .base import BaseConverter
+
+ImageSizeType = Tuple[int, int]
+
+
+class ToMaskConverter(BaseConverter):
+    """
+    Converts various DensePose predictor outputs to masks
+    in bit mask format (see `BitMasks`). Each DensePose predictor output type
+    has to register its convertion strategy.
+    """
+
+    registry = {}
+    dst_type = BitMasks
+
+    @classmethod
+    # pyre-fixme[14]: `convert` overrides method defined in `BaseConverter`
+    #  inconsistently.
+    def convert(
+        cls,
+        densepose_predictor_outputs: Any,
+        boxes: Boxes,
+        image_size_hw: ImageSizeType,
+        *args,
+        **kwargs
+    ) -> BitMasks:
+        """
+        Convert DensePose predictor outputs to BitMasks using some registered
+        converter. Does recursive lookup for base classes, so there's no need
+        for explicit registration for derived classes.
+
+        Args:
+            densepose_predictor_outputs: DensePose predictor output to be
+                converted to BitMasks
+            boxes (Boxes): bounding boxes that correspond to the DensePose
+                predictor outputs
+            image_size_hw (tuple [int, int]): image height and width
+        Return:
+            An instance of `BitMasks`. If no suitable converter was found, raises KeyError
+        """
+        return super(ToMaskConverter, cls).convert(
+            densepose_predictor_outputs, boxes, image_size_hw, *args, **kwargs
+        )