tensorflow/models · error · ValueError

Expected the last dimension of `bbox` has size == 4, but the

Error message

Expected the last dimension of `bbox` has size == 4, but the shape of `bbox` was: %s

What it means

Error "Expected the last dimension of `bbox` has size == 4, but the shape of `bbox` was: %s" thrown in tensorflow/models.

Source

Thrown at official/vision/ops/box_ops.py:899

  Returns:
    A tensor in shape (..., height, width) which stores the bitmasks created
    from the bounding boxes. For example:

    >>> bbox2mask(tf.constant([[1,2,4,4]]),
                  image_height=5,
                  image_width=5,
                  dtype=tf.int32)
    <tf.Tensor: shape=(1, 5, 5), dtype=int32, numpy=
    array([[[0, 0, 0, 0, 0],
            [0, 0, 1, 1, 0],
            [0, 0, 1, 1, 0],
            [0, 0, 1, 1, 0],
            [0, 0, 0, 0, 0]]], dtype=int32)>
  """
  bbox_shape = bbox.get_shape().as_list()
  if bbox_shape[-1] != 4:
    raise ValueError(
        'Expected the last dimension of `bbox` has size == 4, but the shape '
        'of `bbox` was: %s' % bbox_shape)

  # (..., 1)
  ymin = bbox[..., 0:1]
  xmin = bbox[..., 1:2]
  ymax = bbox[..., 2:3]
  xmax = bbox[..., 3:4]
  # (..., 1, width)
  ymin = tf.expand_dims(tf.repeat(ymin, repeats=image_width, axis=-1), axis=-2)
  # (..., height, 1)
  xmin = tf.expand_dims(tf.repeat(xmin, repeats=image_height, axis=-1), axis=-1)
  # (..., 1, width)
  ymax = tf.expand_dims(tf.repeat(ymax, repeats=image_width, axis=-1), axis=-2)
  # (..., height, 1)
  xmax = tf.expand_dims(tf.repeat(xmax, repeats=image_height, axis=-1), axis=-1)

  # (height, 1)

View on GitHub (pinned to e006f5f0d5)

Solutions

1. Pass bbox with last dimension of size 4 ([y1, x1, y2, x2]).
2. Fix the bbox tensor shape before calling this op.

When it happens

Trigger: Thrown at official/vision/ops/box_ops.py:899 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of tensorflow/models@e006f5f0d5 (2026-08-24). Data as JSON: /api/errors/569041b814829481. Report an issue: GitHub.