Issue with OpenCV and too many descriptors in matching

[mhhd2020]

When uploading an A0 sketch map, the following error message appears. Probably due to too many descriptors (cf. https://stackoverflow.com/questions/20432403/error-215-traindesccollectioniidx-python-opencv)

Arguments: {'hostname': 'celery@H0108', 'id': 'a3a9bc42-27a9-4792-a65d-9cce615c278b', 'name': 'sketch_map_tool.tasks.digitize_sketches', 'exc': 'error("OpenCV(4.7.0) /io/opencv/modules/features2d/src/matchers.cpp:860: error: (-215:Assertion failed) trainDescCollection[iIdx].rows < IMGIDX_ONE in function 'knnMatchImpl'\n")', 'traceback': 'Traceback (most recent call last):
  File "/home/matthias/.cache/pypoetry/virtualenvs/sketch-map-tool-SFkv235P-py3.11/lib/python3.11/site-packages/celery/app/trace.py", line 451, in trace_task
    R = retval = fun(*args, **kwargs)
                 ^^^^^^^^^^^^^^^^^^^^
  File "/home/matthias/work/smt/sketch_map_tool/__init__.py", line 46, in __call__
    return self.run(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/matthias/work/smt/sketch_map_tool/tasks.py", line 146, in digitize_sketches
    [process(file_id, name) for file_id, name in zip(file_ids, file_names)]
  File "/home/matthias/work/smt/sketch_map_tool/tasks.py", line 146, in <listcomp>
    [process(file_id, name) for file_id, name in zip(file_ids, file_names)]
     ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/matthias/work/smt/sketch_map_tool/tasks.py", line 132, in process
    r = clip(r, map_frame)
        ^^^^^^^^^^^^^^^^^^
  File "/home/matthias/work/smt/sketch_map_tool/upload_processing/clip.py", line 28, in clip
    matches = list(matcher.match(desc1, desc2, None))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cv2.error: OpenCV(4.7.0) /io/opencv/modules/features2d/src/matchers.cpp:860: error: (-215:Assertion failed) trainDescCollection[iIdx].rows < IMGIDX_ONE in function 'knnMatchImpl'

', 'args': "([14], ['Screenshot_2023-07-05_at_14-35-05_untitled_-_sketch-map-18.pdf_copy_4.png'], array([[[154, 204, 169],
        [199, 232, 217],
        [232, 253, 253],
        ...,
        [118, 118, 118],
        [118, 118, 118],
        [ 55,  55,  55]],

       [[154, 204, 169],
        [217, 246, 247],
        [232, 253, 253],
        ...,
        [255, 255, 255],
        [255, 255, 255],
        [119, 119, 119]],

       [[170, 196, 197],
        [217, 246, 247],
        [232, 253, 253],
        ...,
        [255, 255, 255],
        [255, 255, 255],
        [119, 119, 119]],

       ...,

       [[199, 206, 214],
        [199, 206, 214],
        [201, 208, 216],
        ...,
        [201, 208, 216],
        [201, 208, 216],
        [201, 208, 216]],

       [[199, 206, 214],
        [199, 206, 214],
        [199, 206, 214],
        ...,
        [201, 208, 216],
        [201, 208, 216],
        [201, 208, 216]],

       [[199, 206, 214],
        [201, 208, 216],
        [199, 206, 214],
        ...,
        [201, 208, 216],
        [201, 208, 216],
        [201, 208, 216]]], dtype=uint8), Bbox(lon_min=964668.3060772641, lat_min=6343605.938051963, lon_max=967431.3455614758, lat_max=6345832.086898304))", 'kwargs': '{}', 'description': 'raised unexpected', 'internal': False}

[matthiasschaub]

Is fixed by limiting the keypoints.