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#!/usr/bin/env python3
# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
import torch
from .box_head.box_head import build_roi_box_head
from .mask_head.mask_head import build_roi_mask_head
class CombinedROIHeads(torch.nn.ModuleDict):
"""
Combines a set of individual heads (for box prediction or masks) into a single
head.
"""
def __init__(self, cfg, heads):
super(CombinedROIHeads, self).__init__(heads)
self.cfg = cfg.clone()
if cfg.MODEL.MASK_ON and cfg.MODEL.ROI_MASK_HEAD.SHARE_BOX_FEATURE_EXTRACTOR:
self.mask.feature_extractor = self.box.feature_extractor
def forward(self, features, proposals, targets=None):
losses = {}
# TODO rename x to roi_box_features, if it doesn't increase memory consumption
x, detections, loss_box = self.box(features, proposals, targets)
losses.update(loss_box)
if self.cfg.MODEL.MASK_ON or self.cfg.SEQUENCE.SEQ_ON:
mask_features = features
# optimization: during training, if we share the feature extractor between
# the box and the mask heads,
# then we can reuse the features already computed
if (
self.training
and self.cfg.MODEL.ROI_MASK_HEAD.SHARE_BOX_FEATURE_EXTRACTOR
):
mask_features = x
# During training, self.box() will return
# the unaltered proposals as "detections"
# this makes the API consistent during training and testing
x, detections, loss_mask = self.mask(mask_features, detections, targets)
if loss_mask is not None:
losses.update(loss_mask)
return x, detections, losses
def build_roi_heads(cfg):
# individually create the heads, that will be combined together
# afterwards
roi_heads = []
if not cfg.MODEL.RPN_ONLY:
roi_heads.append(("box", build_roi_box_head(cfg)))
if cfg.MODEL.MASK_ON or cfg.SEQUENCE.SEQ_ON:
roi_heads.append(("mask", build_roi_mask_head(cfg)))
# combine individual heads in a single module
if roi_heads:
roi_heads = CombinedROIHeads(cfg, roi_heads)
return roi_heads