open-mmlab/mmdetection · error · NotImplementedError

Regression head is not supported yet.

Error message

Regression head is not supported yet.

What it means

RoITrackHead (base class of QuasiDenseTrackHead) only initializes an embed head; passing regress_head raises NotImplementedError since the regression branch is not implemented in mmdet.

Source

Thrown at mmdet/models/tracking_heads/roi_track_head.py:46

    def __init__(self,
                 roi_extractor: Optional[dict] = None,
                 embed_head: Optional[dict] = None,
                 regress_head: Optional[dict] = None,
                 train_cfg: Optional[dict] = None,
                 test_cfg: Optional[dict] = None,
                 init_cfg: Optional[dict] = None,
                 *args,
                 **kwargs):
        super().__init__(init_cfg=init_cfg)
        self.train_cfg = train_cfg
        self.test_cfg = test_cfg

        if embed_head is not None:
            self.init_embed_head(roi_extractor, embed_head)

        if regress_head is not None:
            raise NotImplementedError('Regression head is not supported yet.')

        self.init_assigner_sampler()

    def init_embed_head(self, roi_extractor, embed_head) -> None:
        """Initialize ``embed_head``"""
        self.roi_extractor = MODELS.build(roi_extractor)
        self.embed_head = MODELS.build(embed_head)

    def init_assigner_sampler(self) -> None:
        """Initialize assigner and sampler."""
        self.bbox_assigner = None
        self.bbox_sampler = None
        if self.train_cfg:
            self.bbox_assigner = TASK_UTILS.build(self.train_cfg.assigner)
            self.bbox_sampler = TASK_UTILS.build(
                self.train_cfg.sampler, default_args=dict(context=self))

    @property

View on GitHub (pinned to cfd5d3a985)

Solutions

1. Drop regress_head from the config
2. In custom subclasses that do implement regression, override __init__ to handle regress_head before calling super() with regress_head=None

Example fix

# before
head=dict(type='RoITrackHead', embed_head=..., regress_head=...)
# after
head=dict(type='RoITrackHead', embed_head=...)  # omit regress_head

assert not cfg.get('regress_head'), 'RoITrackHead regress_head unsupported'

When it happens

Trigger: Any track head derived from RoITrackHead constructed with a non-None regress_head in its config.

Common situations: Custom track heads inheriting RoITrackHead while forwarding a regress_head kwarg from the config; or config drift from upstream QDTrack.

Related errors

• Regression head is not supported yet.
• trackeval is not installed,please install it by: pip install
• metric must be a list or a str.
• metric {metric} is not supported.
• _forward function (namely 'tensor' mode) is not supported no

AI-assisted analysis of open-mmlab/mmdetection@cfd5d3a985 (2026-08-27). Data as JSON: /api/errors/eb47b69525c796de. Report an issue: GitHub.