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# Copyright (c) Facebook, Inc. and its affiliates. | |
import itertools | |
import json | |
import logging | |
import numpy as np | |
import os | |
from collections import OrderedDict | |
from typing import Optional, Union | |
import pycocotools.mask as mask_util | |
import torch | |
from PIL import Image | |
from detectron2.data import DatasetCatalog, MetadataCatalog | |
from detectron2.utils.comm import all_gather, is_main_process, synchronize | |
from detectron2.utils.file_io import PathManager | |
from .evaluator import DatasetEvaluator | |
_CV2_IMPORTED = True | |
try: | |
import cv2 # noqa | |
except ImportError: | |
# OpenCV is an optional dependency at the moment | |
_CV2_IMPORTED = False | |
def load_image_into_numpy_array( | |
filename: str, | |
copy: bool = False, | |
dtype: Optional[Union[np.dtype, str]] = None, | |
) -> np.ndarray: | |
with PathManager.open(filename, "rb") as f: | |
array = np.array(Image.open(f), copy=copy, dtype=dtype) | |
return array | |
class SemSegEvaluator(DatasetEvaluator): | |
""" | |
Evaluate semantic segmentation metrics. | |
""" | |
def __init__( | |
self, | |
dataset_name, | |
distributed=True, | |
output_dir=None, | |
*, | |
sem_seg_loading_fn=load_image_into_numpy_array, | |
num_classes=None, | |
ignore_label=None, | |
): | |
""" | |
Args: | |
dataset_name (str): name of the dataset to be evaluated. | |
distributed (bool): if True, will collect results from all ranks for evaluation. | |
Otherwise, will evaluate the results in the current process. | |
output_dir (str): an output directory to dump results. | |
sem_seg_loading_fn: function to read sem seg file and load into numpy array. | |
Default provided, but projects can customize. | |
num_classes, ignore_label: deprecated argument | |
""" | |
self._logger = logging.getLogger(__name__) | |
if num_classes is not None: | |
self._logger.warn( | |
"SemSegEvaluator(num_classes) is deprecated! It should be obtained from metadata." | |
) | |
if ignore_label is not None: | |
self._logger.warn( | |
"SemSegEvaluator(ignore_label) is deprecated! It should be obtained from metadata." | |
) | |
self._dataset_name = dataset_name | |
self._distributed = distributed | |
self._output_dir = output_dir | |
self._cpu_device = torch.device("cpu") | |
self.input_file_to_gt_file = { | |
dataset_record["file_name"]: dataset_record["sem_seg_file_name"] | |
for dataset_record in DatasetCatalog.get(dataset_name) | |
} | |
meta = MetadataCatalog.get(dataset_name) | |
# Dict that maps contiguous training ids to COCO category ids | |
try: | |
c2d = meta.stuff_dataset_id_to_contiguous_id | |
self._contiguous_id_to_dataset_id = {v: k for k, v in c2d.items()} | |
except AttributeError: | |
self._contiguous_id_to_dataset_id = None | |
self._class_names = meta.stuff_classes | |
self.sem_seg_loading_fn = sem_seg_loading_fn | |
self._num_classes = len(meta.stuff_classes) | |
if num_classes is not None: | |
assert self._num_classes == num_classes, f"{self._num_classes} != {num_classes}" | |
self._ignore_label = ignore_label if ignore_label is not None else meta.ignore_label | |
# This is because cv2.erode did not work for int datatype. Only works for uint8. | |
self._compute_boundary_iou = True | |
if not _CV2_IMPORTED: | |
self._compute_boundary_iou = False | |
self._logger.warn( | |
"""Boundary IoU calculation requires OpenCV. B-IoU metrics are | |
not going to be computed because OpenCV is not available to import.""" | |
) | |
if self._num_classes >= np.iinfo(np.uint8).max: | |
self._compute_boundary_iou = False | |
self._logger.warn( | |
f"""SemSegEvaluator(num_classes) is more than supported value for Boundary IoU | |
calculation! B-IoU metrics are not going to be computed. Max allowed value | |
(exclusive) for num_classes for calculating Boundary IoU is. | |
{np.iinfo(np.uint8).max} The number of classes of dataset {self._dataset_name} is | |
{self._num_classes}""" | |
) | |
def reset(self): | |
self._conf_matrix = np.zeros((self._num_classes + 1, self._num_classes + 1), dtype=np.int64) | |
self._b_conf_matrix = np.zeros( | |
(self._num_classes + 1, self._num_classes + 1), dtype=np.int64 | |
) | |
self._predictions = [] | |
def process(self, inputs, outputs): | |
""" | |
Args: | |
inputs: the inputs to a model. | |
It is a list of dicts. Each dict corresponds to an image and | |
contains keys like "height", "width", "file_name". | |
outputs: the outputs of a model. It is either list of semantic segmentation predictions | |
(Tensor [H, W]) or list of dicts with key "sem_seg" that contains semantic | |
segmentation prediction in the same format. | |
""" | |
for input, output in zip(inputs, outputs): | |
output = output["sem_seg"].argmax(dim=0).to(self._cpu_device) | |
pred = np.array(output, dtype=int) | |
gt_filename = self.input_file_to_gt_file[input["file_name"]] | |
gt = self.sem_seg_loading_fn(gt_filename, dtype=int) | |
gt[gt == self._ignore_label] = self._num_classes | |
self._conf_matrix += np.bincount( | |
(self._num_classes + 1) * pred.reshape(-1) + gt.reshape(-1), | |
minlength=self._conf_matrix.size, | |
).reshape(self._conf_matrix.shape) | |
if self._compute_boundary_iou: | |
b_gt = self._mask_to_boundary(gt.astype(np.uint8)) | |
b_pred = self._mask_to_boundary(pred.astype(np.uint8)) | |
self._b_conf_matrix += np.bincount( | |
(self._num_classes + 1) * b_pred.reshape(-1) + b_gt.reshape(-1), | |
minlength=self._conf_matrix.size, | |
).reshape(self._conf_matrix.shape) | |
self._predictions.extend(self.encode_json_sem_seg(pred, input["file_name"])) | |
def evaluate(self): | |
""" | |
Evaluates standard semantic segmentation metrics (http://cocodataset.org/#stuff-eval): | |
* Mean intersection-over-union averaged across classes (mIoU) | |
* Frequency Weighted IoU (fwIoU) | |
* Mean pixel accuracy averaged across classes (mACC) | |
* Pixel Accuracy (pACC) | |
""" | |
if self._distributed: | |
synchronize() | |
conf_matrix_list = all_gather(self._conf_matrix) | |
b_conf_matrix_list = all_gather(self._b_conf_matrix) | |
self._predictions = all_gather(self._predictions) | |
self._predictions = list(itertools.chain(*self._predictions)) | |
if not is_main_process(): | |
return | |
self._conf_matrix = np.zeros_like(self._conf_matrix) | |
for conf_matrix in conf_matrix_list: | |
self._conf_matrix += conf_matrix | |
self._b_conf_matrix = np.zeros_like(self._b_conf_matrix) | |
for b_conf_matrix in b_conf_matrix_list: | |
self._b_conf_matrix += b_conf_matrix | |
if self._output_dir: | |
PathManager.mkdirs(self._output_dir) | |
file_path = os.path.join(self._output_dir, "sem_seg_predictions.json") | |
with PathManager.open(file_path, "w") as f: | |
f.write(json.dumps(self._predictions)) | |
acc = np.full(self._num_classes, np.nan, dtype=float) | |
iou = np.full(self._num_classes, np.nan, dtype=float) | |
tp = self._conf_matrix.diagonal()[:-1].astype(float) | |
pos_gt = np.sum(self._conf_matrix[:-1, :-1], axis=0).astype(float) | |
class_weights = pos_gt / np.sum(pos_gt) | |
pos_pred = np.sum(self._conf_matrix[:-1, :-1], axis=1).astype(float) | |
acc_valid = pos_gt > 0 | |
acc[acc_valid] = tp[acc_valid] / pos_gt[acc_valid] | |
union = pos_gt + pos_pred - tp | |
iou_valid = np.logical_and(acc_valid, union > 0) | |
iou[iou_valid] = tp[iou_valid] / union[iou_valid] | |
macc = np.sum(acc[acc_valid]) / np.sum(acc_valid) | |
miou = np.sum(iou[iou_valid]) / np.sum(iou_valid) | |
fiou = np.sum(iou[iou_valid] * class_weights[iou_valid]) | |
pacc = np.sum(tp) / np.sum(pos_gt) | |
if self._compute_boundary_iou: | |
b_iou = np.full(self._num_classes, np.nan, dtype=float) | |
b_tp = self._b_conf_matrix.diagonal()[:-1].astype(float) | |
b_pos_gt = np.sum(self._b_conf_matrix[:-1, :-1], axis=0).astype(float) | |
b_pos_pred = np.sum(self._b_conf_matrix[:-1, :-1], axis=1).astype(float) | |
b_union = b_pos_gt + b_pos_pred - b_tp | |
b_iou_valid = b_union > 0 | |
b_iou[b_iou_valid] = b_tp[b_iou_valid] / b_union[b_iou_valid] | |
res = {} | |
res["mIoU"] = 100 * miou | |
res["fwIoU"] = 100 * fiou | |
for i, name in enumerate(self._class_names): | |
res[f"IoU-{name}"] = 100 * iou[i] | |
if self._compute_boundary_iou: | |
res[f"BoundaryIoU-{name}"] = 100 * b_iou[i] | |
res[f"min(IoU, B-Iou)-{name}"] = 100 * min(iou[i], b_iou[i]) | |
res["mACC"] = 100 * macc | |
res["pACC"] = 100 * pacc | |
for i, name in enumerate(self._class_names): | |
res[f"ACC-{name}"] = 100 * acc[i] | |
if self._output_dir: | |
file_path = os.path.join(self._output_dir, "sem_seg_evaluation.pth") | |
with PathManager.open(file_path, "wb") as f: | |
torch.save(res, f) | |
results = OrderedDict({"sem_seg": res}) | |
self._logger.info(results) | |
return results | |
def encode_json_sem_seg(self, sem_seg, input_file_name): | |
""" | |
Convert semantic segmentation to COCO stuff format with segments encoded as RLEs. | |
See http://cocodataset.org/#format-results | |
""" | |
json_list = [] | |
for label in np.unique(sem_seg): | |
if self._contiguous_id_to_dataset_id is not None: | |
assert ( | |
label in self._contiguous_id_to_dataset_id | |
), "Label {} is not in the metadata info for {}".format(label, self._dataset_name) | |
dataset_id = self._contiguous_id_to_dataset_id[label] | |
else: | |
dataset_id = int(label) | |
mask = (sem_seg == label).astype(np.uint8) | |
mask_rle = mask_util.encode(np.array(mask[:, :, None], order="F"))[0] | |
mask_rle["counts"] = mask_rle["counts"].decode("utf-8") | |
json_list.append( | |
{"file_name": input_file_name, "category_id": dataset_id, "segmentation": mask_rle} | |
) | |
return json_list | |
def _mask_to_boundary(self, mask: np.ndarray, dilation_ratio=0.02): | |
assert mask.ndim == 2, "mask_to_boundary expects a 2-dimensional image" | |
h, w = mask.shape | |
diag_len = np.sqrt(h**2 + w**2) | |
dilation = max(1, int(round(dilation_ratio * diag_len))) | |
kernel = np.ones((3, 3), dtype=np.uint8) | |
padded_mask = cv2.copyMakeBorder(mask, 1, 1, 1, 1, cv2.BORDER_CONSTANT, value=0) | |
eroded_mask_with_padding = cv2.erode(padded_mask, kernel, iterations=dilation) | |
eroded_mask = eroded_mask_with_padding[1:-1, 1:-1] | |
boundary = mask - eroded_mask | |
return boundary | |