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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 custom_pycocotools.mask as mask_util
import torch
from PIL import Image
from custom_detectron2.data import DatasetCatalog, MetadataCatalog
from custom_detectron2.utils.comm import all_gather, is_main_process, synchronize
from custom_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=np.int)
gt_filename = self.input_file_to_gt_file[input["file_name"]]
gt = self.sem_seg_loading_fn(gt_filename, dtype=np.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=np.float)
iou = np.full(self._num_classes, np.nan, dtype=np.float)
tp = self._conf_matrix.diagonal()[:-1].astype(np.float)
pos_gt = np.sum(self._conf_matrix[:-1, :-1], axis=0).astype(np.float)
class_weights = pos_gt / np.sum(pos_gt)
pos_pred = np.sum(self._conf_matrix[:-1, :-1], axis=1).astype(np.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=np.float)
b_tp = self._b_conf_matrix.diagonal()[:-1].astype(np.float)
b_pos_gt = np.sum(self._b_conf_matrix[:-1, :-1], axis=0).astype(np.float)
b_pos_pred = np.sum(self._b_conf_matrix[:-1, :-1], axis=1).astype(np.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