Exemple #1
0
def convert_to_coco_json(dataset_name, output_file, allow_cached=True):
    """
    Converts dataset into COCO format and saves it to a json file.
    dataset_name must be registered in DatasetCatalog and in detectron2's standard format.

    Args:
        dataset_name:
            reference from the config file to the catalogs
            must be registered in DatasetCatalog and in detectron2's standard format
        output_file: path of json file that will be saved to
        allow_cached: if json file is already present then skip conversion
    """

    # TODO: The dataset or the conversion script *may* change,
    # a checksum would be useful for validating the cached data

    PathManager.mkdirs(os.path.dirname(output_file))
    with file_lock(output_file):
        if PathManager.exists(output_file) and allow_cached:
            logger.warning(
                f"Using previously cached COCO format annotations at '{output_file}'. "
                "You need to clear the cache file if your dataset has been modified."
            )
        else:
            logger.info(
                f"Converting annotations of dataset '{dataset_name}' to COCO format ...)"
            )
            coco_dict = convert_to_coco_dict(dataset_name)

            logger.info(
                f"Caching COCO format annotations at '{output_file}' ...")
            tmp_file = output_file + ".tmp"
            with PathManager.open(tmp_file, "w") as f:
                json.dump(coco_dict, f)
            shutil.move(tmp_file, output_file)
    def evaluate(self, img_ids=None):
        """
        Args:
            img_ids: a list of image IDs to evaluate on. Default to None for the whole dataset
        """
        if self._distributed:
            comm.synchronize()
            predictions = comm.gather(self._predictions, dst=0)
            predictions = list(itertools.chain(*predictions))

            if not comm.is_main_process():
                return {}
        else:
            predictions = self._predictions

        if len(predictions) == 0:
            self._logger.warning("[COCOEvaluator] Did not receive valid predictions.")
            return {}

        if self._output_dir:
            PathManager.mkdirs(self._output_dir)
            file_path = os.path.join(self._output_dir, "instances_predictions.pth")
            with PathManager.open(file_path, "wb") as f:
                torch.save(predictions, f)

        self._results = OrderedDict()
        if "proposals" in predictions[0]:
            self._eval_box_proposals(predictions)
        if "instances" in predictions[0]:
            self._eval_predictions(predictions, img_ids=img_ids)
        # Copy so the caller can do whatever with results
        return copy.deepcopy(self._results)
def default_setup(cfg, args):
    """
    Perform some basic common setups at the beginning of a job, including:

    1. Set up the detectron2 logger
    2. Log basic information about environment, cmdline arguments, and config
    3. Backup the config to the output directory

    Args:
        cfg (CfgNode or omegaconf.DictConfig): the full config to be used
        args (argparse.NameSpace): the command line arguments to be logged
    """
    output_dir = _try_get_key(cfg, "OUTPUT_DIR", "output_dir",
                              "train.output_dir")
    if comm.is_main_process() and output_dir:
        PathManager.mkdirs(output_dir)

    rank = comm.get_rank()
    setup_logger(output_dir, distributed_rank=rank, name="fvcore")
    logger = setup_logger(output_dir, distributed_rank=rank)

    logger.info("Rank of current process: {}. World size: {}".format(
        rank, comm.get_world_size()))
    logger.info("Environment info:\n" + collect_env_info())

    logger.info("Command line arguments: " + str(args))
    if hasattr(args, "config_file") and args.config_file != "":
        logger.info("Contents of args.config_file={}:\n{}".format(
            args.config_file,
            _highlight(
                PathManager.open(args.config_file, "r").read(),
                args.config_file),
        ))

    if comm.is_main_process() and output_dir:
        # Note: some of our scripts may expect the existence of
        # config.yaml in output directory
        path = os.path.join(output_dir, "config.yaml")
        if isinstance(cfg, CfgNode):
            logger.info("Running with full config:\n{}".format(
                _highlight(cfg.dump(), ".yaml")))
            with PathManager.open(path, "w") as f:
                f.write(cfg.dump())
        else:
            LazyConfig.save(cfg, path)
        logger.info("Full config saved to {}".format(path))

    # make sure each worker has a different, yet deterministic seed if specified
    seed = _try_get_key(cfg, "SEED", "train.seed", default=-1)
    seed_all_rng(None if seed < 0 else seed + rank)

    # cudnn benchmark has large overhead. It shouldn't be used considering the small size of
    # typical validation set.
    if not (hasattr(args, "eval_only") and args.eval_only):
        torch.backends.cudnn.benchmark = _try_get_key(cfg,
                                                      "CUDNN_BENCHMARK",
                                                      "train.cudnn_benchmark",
                                                      default=False)
Exemple #4
0
    def load(filename: str, keys: Union[None, str, Tuple[str, ...]] = None):
        """
        Load a config file.

        Args:
            filename: absolute path or relative path w.r.t. the current working directory
            keys: keys to load and return. If not given, return all keys
                (whose values are config objects) in a dict.
        """
        has_keys = keys is not None
        filename = filename.replace("/./", "/")  # redundant
        if os.path.splitext(filename)[1] not in [".py", ".yaml", ".yml"]:
            raise ValueError(f"Config file {filename} has to be a python or yaml file.")
        if filename.endswith(".py"):
            _validate_py_syntax(filename)

            with _patch_import():
                # Record the filename
                module_namespace = {
                    "__file__": filename,
                    "__package__": _random_package_name(filename),
                }
                with PathManager.open(filename) as f:
                    content = f.read()
                # Compile first with filename to:
                # 1. make filename appears in stacktrace
                # 2. make load_rel able to find its parent's (possibly remote) location
                exec(compile(content, filename, "exec"), module_namespace)

            ret = module_namespace
        else:
            with PathManager.open(filename) as f:
                obj = yaml.unsafe_load(f)
            ret = OmegaConf.create(obj, flags={"allow_objects": True})

        if has_keys:
            if isinstance(keys, str):
                return _cast_to_config(ret[keys])
            else:
                return tuple(_cast_to_config(ret[a]) for a in keys)
        else:
            if filename.endswith(".py"):
                # when not specified, only load those that are config objects
                ret = DictConfig(
                    {
                        name: _cast_to_config(value)
                        for name, value in ret.items()
                        if isinstance(value, (DictConfig, ListConfig, dict))
                        and not name.startswith("_")
                    },
                    flags={"allow_objects": True},
                )
            return ret
    def _eval_predictions(self, predictions, img_ids=None):
        """
        Evaluate predictions. Fill self._results with the metrics of the tasks.
        """
        self._logger.info("Preparing results for COCO format ...")
        coco_results = list(itertools.chain(*[x["instances"] for x in predictions]))
        tasks = self._tasks or self._tasks_from_predictions(coco_results)

        # unmap the category ids for COCO
        if hasattr(self._metadata, "thing_dataset_id_to_contiguous_id"):
            dataset_id_to_contiguous_id = self._metadata.thing_dataset_id_to_contiguous_id
            all_contiguous_ids = list(dataset_id_to_contiguous_id.values())
            num_classes = len(all_contiguous_ids)
            assert min(all_contiguous_ids) == 0 and max(all_contiguous_ids) == num_classes - 1

            reverse_id_mapping = {v: k for k, v in dataset_id_to_contiguous_id.items()}
            for result in coco_results:
                category_id = result["category_id"]
                assert category_id < num_classes, (
                    f"A prediction has class={category_id}, "
                    f"but the dataset only has {num_classes} classes and "
                    f"predicted class id should be in [0, {num_classes - 1}]."
                )
                result["category_id"] = reverse_id_mapping[category_id]

        if self._output_dir:
            file_path = os.path.join(self._output_dir, "coco_instances_results.json")
            self._logger.info("Saving results to {}".format(file_path))
            with PathManager.open(file_path, "w") as f:
                f.write(json.dumps(coco_results))
                f.flush()

        if not self._do_evaluation:
            self._logger.info("Annotations are not available for evaluation.")
            return

        self._logger.info(
            "Evaluating predictions with {} COCO API...".format(
                "unofficial" if self._use_fast_impl else "official"
            )
        )
        for task in sorted(tasks):
            assert task in {"bbox", "segm", "keypoints"}, f"Got unknown task: {task}!"
            coco_eval = (
                _evaluate_predictions_on_coco(
                    self._coco_api,
                    coco_results,
                    task,
                    kpt_oks_sigmas=self._kpt_oks_sigmas,
                    use_fast_impl=self._use_fast_impl,
                    img_ids=img_ids,
                )
                if len(coco_results) > 0
                else None  # cocoapi does not handle empty results very well
            )

            res = self._derive_coco_results(
                coco_eval, task, class_names=self._metadata.get("thing_classes")
            )
            self._results[task] = res
Exemple #6
0
def _validate_py_syntax(filename):
    # see also https://github.com/open-mmlab/mmcv/blob/master/mmcv/utils/config.py
    with PathManager.open(filename, "r") as f:
        content = f.read()
    try:
        ast.parse(content)
    except SyntaxError as e:
        raise SyntaxError(f"Config file {filename} has syntax error!") from e
    def _load_file(self, filename):
        if filename.endswith(".pkl"):
            with PathManager.open(filename, "rb") as f:
                data = pickle.load(f, encoding="latin1")
            if "model" in data and "__author__" in data:
                # file is in Detectron2 model zoo format
                self.logger.info("Reading a file from '{}'".format(
                    data["__author__"]))
                return data
            else:
                # assume file is from Caffe2 / Detectron1 model zoo
                if "blobs" in data:
                    # Detection models have "blobs", but ImageNet models don't
                    data = data["blobs"]
                data = {
                    k: v
                    for k, v in data.items() if not k.endswith("_momentum")
                }
                return {
                    "model": data,
                    "__author__": "Caffe2",
                    "matching_heuristics": True
                }
        elif filename.endswith(".pyth"):
            # assume file is from pycls; no one else seems to use the ".pyth" extension
            with PathManager.open(filename, "rb") as f:
                data = torch.load(f)
            assert (
                "model_state" in data
            ), f"Cannot load .pyth file {filename}; pycls checkpoints must contain 'model_state'."
            model_state = {
                k: v
                for k, v in data["model_state"].items()
                if not k.endswith("num_batches_tracked")
            }
            return {
                "model": model_state,
                "__author__": "pycls",
                "matching_heuristics": True
            }

        loaded = super()._load_file(filename)  # load native pth checkpoint
        if "model" not in loaded:
            loaded = {"model": loaded}
        return loaded
Exemple #8
0
def load_proposals_into_dataset(dataset_dicts, proposal_file):
    """
    Load precomputed object proposals into the dataset.

    The proposal file should be a pickled dict with the following keys:

    - "ids": list[int] or list[str], the image ids
    - "boxes": list[np.ndarray], each is an Nx4 array of boxes corresponding to the image id
    - "objectness_logits": list[np.ndarray], each is an N sized array of objectness scores
      corresponding to the boxes.
    - "bbox_mode": the BoxMode of the boxes array. Defaults to ``BoxMode.XYXY_ABS``.

    Args:
        dataset_dicts (list[dict]): annotations in Detectron2 Dataset format.
        proposal_file (str): file path of pre-computed proposals, in pkl format.

    Returns:
        list[dict]: the same format as dataset_dicts, but added proposal field.
    """
    logger = logging.getLogger(__name__)
    logger.info("Loading proposals from: {}".format(proposal_file))

    with PathManager.open(proposal_file, "rb") as f:
        proposals = pickle.load(f, encoding="latin1")

    # Rename the key names in D1 proposal files
    rename_keys = {"indexes": "ids", "scores": "objectness_logits"}
    for key in rename_keys:
        if key in proposals:
            proposals[rename_keys[key]] = proposals.pop(key)

    # Fetch the indexes of all proposals that are in the dataset
    # Convert image_id to str since they could be int.
    img_ids = set({str(record["image_id"]) for record in dataset_dicts})
    id_to_index = {
        str(id): i
        for i, id in enumerate(proposals["ids"]) if str(id) in img_ids
    }

    # Assuming default bbox_mode of precomputed proposals are 'XYXY_ABS'
    bbox_mode = BoxMode(proposals["bbox_mode"]
                        ) if "bbox_mode" in proposals else BoxMode.XYXY_ABS

    for record in dataset_dicts:
        # Get the index of the proposal
        i = id_to_index[str(record["image_id"])]

        boxes = proposals["boxes"][i]
        objectness_logits = proposals["objectness_logits"][i]
        # Sort the proposals in descending order of the scores
        inds = objectness_logits.argsort()[::-1]
        record["proposal_boxes"] = boxes[inds]
        record["proposal_objectness_logits"] = objectness_logits[inds]
        record["proposal_bbox_mode"] = bbox_mode

    return dataset_dicts
Exemple #9
0
    def save(cfg, filename: str):
        """
        Save a config object to a yaml file.
        Note that when the config dictionary contains complex objects (e.g. lambda),
        it can't be saved to yaml. In that case we will print an error and
        attempt to save to a pkl file instead.

        Args:
            cfg: an omegaconf config object
            filename: yaml file name to save the config file
        """
        logger = logging.getLogger(__name__)
        try:
            cfg = deepcopy(cfg)
        except Exception:
            pass
        else:
            # if it's deep-copyable, then...
            def _replace_type_by_name(x):
                if "_target_" in x and callable(x._target_):
                    try:
                        x._target_ = _convert_target_to_string(x._target_)
                    except AttributeError:
                        pass

            # not necessary, but makes yaml looks nicer
            _visit_dict_config(cfg, _replace_type_by_name)

        try:
            with PathManager.open(filename, "w") as f:
                dict = OmegaConf.to_container(cfg, resolve=False)
                dumped = yaml.dump(dict, default_flow_style=None, allow_unicode=True, width=9999)
                f.write(dumped)
        except Exception:
            logger.exception("Unable to serialize the config to yaml. Error:")
            new_filename = filename + ".pkl"
            try:
                # retry by pickle
                with PathManager.open(new_filename, "wb") as f:
                    cloudpickle.dump(cfg, f)
                logger.warning(f"Config saved using cloudpickle at {new_filename} ...")
            except Exception:
                pass
Exemple #10
0
 def after_step(self):
     if self._profiler is None:
         return
     self._profiler.__exit__(None, None, None)
     PathManager.mkdirs(self._output_dir)
     out_file = os.path.join(
         self._output_dir,
         "profiler-trace-iter{}.json".format(self.trainer.iter))
     if "://" not in out_file:
         self._profiler.export_chrome_trace(out_file)
     else:
         # Support non-posix filesystems
         with tempfile.TemporaryDirectory(
                 prefix="detectron2_profiler") as d:
             tmp_file = os.path.join(d, "tmp.json")
             self._profiler.export_chrome_trace(tmp_file)
             with open(tmp_file) as f:
                 content = f.read()
         with PathManager.open(out_file, "w") as f:
             f.write(content)
Exemple #11
0
    def merge_from_file(self,
                        cfg_filename: str,
                        allow_unsafe: bool = True) -> None:
        """
        Load content from the given config file and merge it into self.

        Args:
            cfg_filename: config filename
            allow_unsafe: allow unsafe yaml syntax
        """
        assert PathManager.isfile(
            cfg_filename), f"Config file '{cfg_filename}' does not exist!"
        loaded_cfg = self.load_yaml_with_base(cfg_filename,
                                              allow_unsafe=allow_unsafe)
        loaded_cfg = type(self)(loaded_cfg)

        # defaults.py needs to import CfgNode
        from .defaults import _C

        latest_ver = _C.VERSION
        assert (
            latest_ver == self.VERSION
        ), "CfgNode.merge_from_file is only allowed on a config object of latest version!"

        logger = logging.getLogger(__name__)

        loaded_ver = loaded_cfg.get("VERSION", None)
        if loaded_ver is None:
            from .compat import guess_version

            loaded_ver = guess_version(loaded_cfg, cfg_filename)
        assert loaded_ver <= self.VERSION, "Cannot merge a v{} config into a v{} config.".format(
            loaded_ver, self.VERSION)

        if loaded_ver == self.VERSION:
            self.merge_from_other_cfg(loaded_cfg)
        else:
            # compat.py needs to import CfgNode
            from .compat import upgrade_config, downgrade_config

            logger.warning(
                "Loading an old v{} config file '{}' by automatically upgrading to v{}. "
                "See docs/CHANGELOG.md for instructions to update your files.".
                format(loaded_ver, cfg_filename, self.VERSION))
            # To convert, first obtain a full config at an old version
            old_self = downgrade_config(self, to_version=loaded_ver)
            old_self.merge_from_other_cfg(loaded_cfg)
            new_config = upgrade_config(old_self)
            self.clear()
            self.update(new_config)
Exemple #12
0
 def find_relative_file(original_file, relative_import_path, level):
     cur_file = os.path.dirname(original_file)
     for _ in range(level - 1):
         cur_file = os.path.dirname(cur_file)
     cur_name = relative_import_path.lstrip(".")
     for part in cur_name.split("."):
         cur_file = os.path.join(cur_file, part)
     # NOTE: directory import is not handled. Because then it's unclear
     # if such import should produce python module or DictConfig. This can
     # be discussed further if needed.
     if not cur_file.endswith(".py"):
         cur_file += ".py"
     if not PathManager.isfile(cur_file):
         raise ImportError(
             f"Cannot import name {relative_import_path} from "
             f"{original_file}: {cur_file} has to exist."
         )
     return cur_file
def read_image(file_name, format=None):
    """
    Read an image into the given format.
    Will apply rotation and flipping if the image has such exif information.

    Args:
        file_name (str): image file path
        format (str): one of the supported image modes in PIL, or "BGR" or "YUV-BT.601".

    Returns:
        image (np.ndarray):
            an HWC image in the given format, which is 0-255, uint8 for
            supported image modes in PIL or "BGR"; float (0-1 for Y) for YUV-BT.601.
    """
    with PathManager.open(file_name, "rb") as f:
        image = Image.open(f)

        # work around this bug: https://github.com/python-pillow/Pillow/issues/3973
        image = _apply_exif_orientation(image)
        return convert_PIL_to_numpy(image, format)
Exemple #14
0
 def new_import(name, globals=None, locals=None, fromlist=(), level=0):
     if (
         # Only deal with relative imports inside config files
         level != 0
         and globals is not None
         and (globals.get("__package__", "") or "").startswith(_CFG_PACKAGE_NAME)
     ):
         cur_file = find_relative_file(globals["__file__"], name, level)
         _validate_py_syntax(cur_file)
         spec = importlib.machinery.ModuleSpec(
             _random_package_name(cur_file), None, origin=cur_file
         )
         module = importlib.util.module_from_spec(spec)
         module.__file__ = cur_file
         with PathManager.open(cur_file) as f:
             content = f.read()
         exec(compile(content, cur_file, "exec"), module.__dict__)
         for name in fromlist:  # turn imported dict into DictConfig automatically
             val = _cast_to_config(module.__dict__[name])
             module.__dict__[name] = val
         return module
     return old_import(name, globals, locals, fromlist=fromlist, level=level)
    def _eval_box_proposals(self, predictions):
        """
        Evaluate the box proposals in predictions.
        Fill self._results with the metrics for "box_proposals" task.
        """
        if self._output_dir:
            # Saving generated box proposals to file.
            # Predicted box_proposals are in XYXY_ABS mode.
            bbox_mode = BoxMode.XYXY_ABS.value
            ids, boxes, objectness_logits = [], [], []
            for prediction in predictions:
                ids.append(prediction["image_id"])
                boxes.append(prediction["proposals"].proposal_boxes.tensor.numpy())
                objectness_logits.append(prediction["proposals"].objectness_logits.numpy())

            proposal_data = {
                "boxes": boxes,
                "objectness_logits": objectness_logits,
                "ids": ids,
                "bbox_mode": bbox_mode,
            }
            with PathManager.open(os.path.join(self._output_dir, "box_proposals.pkl"), "wb") as f:
                pickle.dump(proposal_data, f)

        if not self._do_evaluation:
            self._logger.info("Annotations are not available for evaluation.")
            return

        self._logger.info("Evaluating bbox proposals ...")
        res = {}
        areas = {"all": "", "small": "s", "medium": "m", "large": "l"}
        for limit in [100, 1000]:
            for area, suffix in areas.items():
                stats = _evaluate_box_proposals(predictions, self._coco_api, area=area, limit=limit)
                key = "AR{}@{:d}".format(suffix, limit)
                res[key] = float(stats["ar"].item() * 100)
        self._logger.info("Proposal metrics: \n" + create_small_table(res))
        self._results["box_proposals"] = res
Exemple #16
0
def load_sem_seg(gt_root, image_root, gt_ext="png", image_ext="jpg"):
    """
    Load semantic segmentation datasets. All files under "gt_root" with "gt_ext" extension are
    treated as ground truth annotations and all files under "image_root" with "image_ext" extension
    as input images. Ground truth and input images are matched using file paths relative to
    "gt_root" and "image_root" respectively without taking into account file extensions.
    This works for COCO as well as some other datasets.

    Args:
        gt_root (str): full path to ground truth semantic segmentation files. Semantic segmentation
            annotations are stored as images with integer values in pixels that represent
            corresponding semantic labels.
        image_root (str): the directory where the input images are.
        gt_ext (str): file extension for ground truth annotations.
        image_ext (str): file extension for input images.

    Returns:
        list[dict]:
            a list of dicts in detectron2 standard format without instance-level
            annotation.

    Notes:
        1. This function does not read the image and ground truth files.
           The results do not have the "image" and "sem_seg" fields.
    """

    # We match input images with ground truth based on their relative filepaths (without file
    # extensions) starting from 'image_root' and 'gt_root' respectively.
    def file2id(folder_path, file_path):
        # extract relative path starting from `folder_path`
        image_id = os.path.normpath(
            os.path.relpath(file_path, start=folder_path))
        # remove file extension
        image_id = os.path.splitext(image_id)[0]
        return image_id

    input_files = sorted(
        (os.path.join(image_root, f)
         for f in PathManager.ls(image_root) if f.endswith(image_ext)),
        key=lambda file_path: file2id(image_root, file_path),
    )
    gt_files = sorted(
        (os.path.join(gt_root, f)
         for f in PathManager.ls(gt_root) if f.endswith(gt_ext)),
        key=lambda file_path: file2id(gt_root, file_path),
    )

    assert len(gt_files) > 0, "No annotations found in {}.".format(gt_root)

    # Use the intersection, so that val2017_100 annotations can run smoothly with val2017 images
    if len(input_files) != len(gt_files):
        logger.warn(
            "Directory {} and {} has {} and {} files, respectively.".format(
                image_root, gt_root, len(input_files), len(gt_files)))
        input_basenames = [
            os.path.basename(f)[:-len(image_ext)] for f in input_files
        ]
        gt_basenames = [os.path.basename(f)[:-len(gt_ext)] for f in gt_files]
        intersect = list(set(input_basenames) & set(gt_basenames))
        # sort, otherwise each worker may obtain a list[dict] in different order
        intersect = sorted(intersect)
        logger.warn("Will use their intersection of {} files.".format(
            len(intersect)))
        input_files = [
            os.path.join(image_root, f + image_ext) for f in intersect
        ]
        gt_files = [os.path.join(gt_root, f + gt_ext) for f in intersect]

    logger.info("Loaded {} images with semantic segmentation from {}".format(
        len(input_files), image_root))

    dataset_dicts = []
    for (img_path, gt_path) in zip(input_files, gt_files):
        record = {}
        record["file_name"] = img_path
        record["sem_seg_file_name"] = gt_path
        dataset_dicts.append(record)

    return dataset_dicts
Exemple #17
0
 def _open_cfg(cls, filename):
     return PathManager.open(filename, "r")
Exemple #18
0
def load_coco_json(json_file,
                   image_root,
                   dataset_name=None,
                   extra_annotation_keys=None):
    """
    Load a json file with COCO's instances annotation format.
    Currently supports instance detection, instance segmentation,
    and person keypoints annotations.

    Args:
        json_file (str): full path to the json file in COCO instances annotation format.
        image_root (str or path-like): the directory where the images in this json file exists.
        dataset_name (str or None): the name of the dataset (e.g., coco_2017_train).
            When provided, this function will also do the following:

            * Put "thing_classes" into the metadata associated with this dataset.
            * Map the category ids into a contiguous range (needed by standard dataset format),
              and add "thing_dataset_id_to_contiguous_id" to the metadata associated
              with this dataset.

            This option should usually be provided, unless users need to load
            the original json content and apply more processing manually.
        extra_annotation_keys (list[str]): list of per-annotation keys that should also be
            loaded into the dataset dict (besides "iscrowd", "bbox", "keypoints",
            "category_id", "segmentation"). The values for these keys will be returned as-is.
            For example, the densepose annotations are loaded in this way.

    Returns:
        list[dict]: a list of dicts in Detectron2 standard dataset dicts format (See
        `Using Custom Datasets </tutorials/datasets.html>`_ ) when `dataset_name` is not None.
        If `dataset_name` is None, the returned `category_ids` may be
        incontiguous and may not conform to the Detectron2 standard format.

    Notes:
        1. This function does not read the image files.
           The results do not have the "image" field.
    """
    from pycocotools.coco import COCO

    timer = Timer()
    json_file = PathManager.get_local_path(json_file)
    with contextlib.redirect_stdout(io.StringIO()):
        coco_api = COCO(json_file)
    if timer.seconds() > 1:
        logger.info("Loading {} takes {:.2f} seconds.".format(
            json_file, timer.seconds()))

    id_map = None
    if dataset_name is not None:
        meta = MetadataCatalog.get(dataset_name)
        cat_ids = sorted(coco_api.getCatIds())
        cats = coco_api.loadCats(cat_ids)
        # The categories in a custom json file may not be sorted.
        thing_classes = [
            c["name"] for c in sorted(cats, key=lambda x: x["id"])
        ]
        meta.thing_classes = thing_classes

        # In COCO, certain category ids are artificially removed,
        # and by convention they are always ignored.
        # We deal with COCO's id issue and translate
        # the category ids to contiguous ids in [0, 80).

        # It works by looking at the "categories" field in the json, therefore
        # if users' own json also have incontiguous ids, we'll
        # apply this mapping as well but print a warning.
        if not (min(cat_ids) == 1 and max(cat_ids) == len(cat_ids)):
            if "coco" not in dataset_name:
                logger.warning("""
Category ids in annotations are not in [1, #categories]! We'll apply a mapping for you.
""")
        id_map = {v: i for i, v in enumerate(cat_ids)}
        meta.thing_dataset_id_to_contiguous_id = id_map

    # sort indices for reproducible results
    img_ids = sorted(coco_api.imgs.keys())
    # imgs is a list of dicts, each looks something like:
    # {'license': 4,
    #  'url': 'http://farm6.staticflickr.com/5454/9413846304_881d5e5c3b_z.jpg',
    #  'file_name': 'COCO_val2014_000000001268.jpg',
    #  'height': 427,
    #  'width': 640,
    #  'date_captured': '2013-11-17 05:57:24',
    #  'id': 1268}
    imgs = coco_api.loadImgs(img_ids)
    # anns is a list[list[dict]], where each dict is an annotation
    # record for an object. The inner list enumerates the objects in an image
    # and the outer list enumerates over images. Example of anns[0]:
    # [{'segmentation': [[192.81,
    #     247.09,
    #     ...
    #     219.03,
    #     249.06]],
    #   'area': 1035.749,
    #   'iscrowd': 0,
    #   'image_id': 1268,
    #   'bbox': [192.81, 224.8, 74.73, 33.43],
    #   'category_id': 16,
    #   'id': 42986},
    #  ...]
    anns = [coco_api.imgToAnns[img_id] for img_id in img_ids]
    total_num_valid_anns = sum([len(x) for x in anns])
    total_num_anns = len(coco_api.anns)
    if total_num_valid_anns < total_num_anns:
        logger.warning(
            f"{json_file} contains {total_num_anns} annotations, but only "
            f"{total_num_valid_anns} of them match to images in the file.")

    if "minival" not in json_file:
        # The popular valminusminival & minival annotations for COCO2014 contain this bug.
        # However the ratio of buggy annotations there is tiny and does not affect accuracy.
        # Therefore we explicitly white-list them.
        ann_ids = [
            ann["id"] for anns_per_image in anns for ann in anns_per_image
        ]
        assert len(set(ann_ids)) == len(
            ann_ids), "Annotation ids in '{}' are not unique!".format(
                json_file)

    imgs_anns = list(zip(imgs, anns))
    logger.info("Loaded {} images in COCO format from {}".format(
        len(imgs_anns), json_file))

    dataset_dicts = []

    ann_keys = ["iscrowd", "bbox", "keypoints", "category_id"
                ] + (extra_annotation_keys or [])

    num_instances_without_valid_segmentation = 0

    for (img_dict, anno_dict_list) in imgs_anns:
        record = {}
        record["file_name"] = os.path.join(image_root, img_dict["file_name"])
        record["height"] = img_dict["height"]
        record["width"] = img_dict["width"]
        image_id = record["image_id"] = img_dict["id"]

        objs = []
        for anno in anno_dict_list:
            # Check that the image_id in this annotation is the same as
            # the image_id we're looking at.
            # This fails only when the data parsing logic or the annotation file is buggy.

            # The original COCO valminusminival2014 & minival2014 annotation files
            # actually contains bugs that, together with certain ways of using COCO API,
            # can trigger this assertion.
            assert anno["image_id"] == image_id

            assert anno.get(
                "ignore",
                0) == 0, '"ignore" in COCO json file is not supported.'

            obj = {key: anno[key] for key in ann_keys if key in anno}
            if "bbox" in obj and len(obj["bbox"]) == 0:
                raise ValueError(
                    f"One annotation of image {image_id} contains empty 'bbox' value! "
                    "This json does not have valid COCO format.")

            segm = anno.get("segmentation", None)
            if segm:  # either list[list[float]] or dict(RLE)
                if isinstance(segm, dict):
                    if isinstance(segm["counts"], list):
                        # convert to compressed RLE
                        segm = mask_util.frPyObjects(segm, *segm["size"])
                else:
                    # filter out invalid polygons (< 3 points)
                    segm = [
                        poly for poly in segm
                        if len(poly) % 2 == 0 and len(poly) >= 6
                    ]
                    if len(segm) == 0:
                        num_instances_without_valid_segmentation += 1
                        continue  # ignore this instance
                obj["segmentation"] = segm

            keypts = anno.get("keypoints", None)
            if keypts:  # list[int]
                for idx, v in enumerate(keypts):
                    if idx % 3 != 2:
                        # COCO's segmentation coordinates are floating points in [0, H or W],
                        # but keypoint coordinates are integers in [0, H-1 or W-1]
                        # Therefore we assume the coordinates are "pixel indices" and
                        # add 0.5 to convert to floating point coordinates.
                        keypts[idx] = v + 0.5
                obj["keypoints"] = keypts

            obj["bbox_mode"] = BoxMode.XYWH_ABS
            if id_map:
                annotation_category_id = obj["category_id"]
                try:
                    obj["category_id"] = id_map[annotation_category_id]
                except KeyError as e:
                    raise KeyError(
                        f"Encountered category_id={annotation_category_id} "
                        "but this id does not exist in 'categories' of the json file."
                    ) from e
            objs.append(obj)
        record["annotations"] = objs
        dataset_dicts.append(record)

    if num_instances_without_valid_segmentation > 0:
        logger.warning(
            "Filtered out {} instances without valid segmentation. ".format(
                num_instances_without_valid_segmentation) +
            "There might be issues in your dataset generation process.  Please "
            "check https://detectron2.readthedocs.io/en/latest/tutorials/datasets.html carefully"
        )
    return dataset_dicts
    def __init__(
        self,
        dataset_name,
        tasks=None,
        distributed=True,
        output_dir=None,
        *,
        use_fast_impl=True,
        kpt_oks_sigmas=(),
    ):
        """
        Args:
            dataset_name (str): name of the dataset to be evaluated.
                It must have either the following corresponding metadata:

                    "json_file": the path to the COCO format annotation

                Or it must be in detectron2's standard dataset format
                so it can be converted to COCO format automatically.
            tasks (tuple[str]): tasks that can be evaluated under the given
                configuration. A task is one of "bbox", "segm", "keypoints".
                By default, will infer this automatically from predictions.
            distributed (True): if True, will collect results from all ranks and run evaluation
                in the main process.
                Otherwise, will only evaluate the results in the current process.
            output_dir (str): optional, an output directory to dump all
                results predicted on the dataset. The dump contains two files:

                1. "instances_predictions.pth" a file that can be loaded with `torch.load` and
                   contains all the results in the format they are produced by the model.
                2. "coco_instances_results.json" a json file in COCO's result format.
            use_fast_impl (bool): use a fast but **unofficial** implementation to compute AP.
                Although the results should be very close to the official implementation in COCO
                API, it is still recommended to compute results with the official API for use in
                papers. The faster implementation also uses more RAM.
            kpt_oks_sigmas (list[float]): The sigmas used to calculate keypoint OKS.
                See http://cocodataset.org/#keypoints-eval
                When empty, it will use the defaults in COCO.
                Otherwise it should be the same length as ROI_KEYPOINT_HEAD.NUM_KEYPOINTS.
        """
        self._logger = logging.getLogger(__name__)
        self._distributed = distributed
        self._output_dir = output_dir
        self._use_fast_impl = use_fast_impl

        if tasks is not None and isinstance(tasks, CfgNode):
            kpt_oks_sigmas = (
                tasks.TEST.KEYPOINT_OKS_SIGMAS if not kpt_oks_sigmas else kpt_oks_sigmas
            )
            self._logger.warn(
                "COCO Evaluator instantiated using config, this is deprecated behavior."
                " Please pass in explicit arguments instead."
            )
            self._tasks = None  # Infering it from predictions should be better
        else:
            self._tasks = tasks

        self._cpu_device = torch.device("cpu")

        self._metadata = MetadataCatalog.get(dataset_name)
        if not hasattr(self._metadata, "json_file"):
            self._logger.info(
                f"'{dataset_name}' is not registered by `register_coco_instances`."
                " Therefore trying to convert it to COCO format ..."
            )

            cache_path = os.path.join(output_dir, f"{dataset_name}_coco_format.json")
            self._metadata.json_file = cache_path
            convert_to_coco_json(dataset_name, cache_path)

        json_file = PathManager.get_local_path(self._metadata.json_file)
        with contextlib.redirect_stdout(io.StringIO()):
            self._coco_api = COCO(json_file)

        # Test set json files do not contain annotations (evaluation must be
        # performed using the COCO evaluation server).
        self._do_evaluation = "annotations" in self._coco_api.dataset
        if self._do_evaluation:
            self._kpt_oks_sigmas = kpt_oks_sigmas