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- import imgviz
- import numpy as np
- import skimage
- from labelme.logger import logger
- def _get_contour_length(contour):
- contour_start = contour
- contour_end = np.r_[contour[1:], contour[0:1]]
- return np.linalg.norm(contour_end - contour_start, axis=1).sum()
- def compute_polygon_from_mask(mask):
- contours = skimage.measure.find_contours(np.pad(mask, pad_width=1))
- if len(contours) == 0:
- logger.warning("No contour found, so returning empty polygon.")
- return np.empty((0, 2), dtype=np.float32)
- contour = max(contours, key=_get_contour_length)
- POLYGON_APPROX_TOLERANCE = 0.004
- polygon = skimage.measure.approximate_polygon(
- coords=contour,
- tolerance=np.ptp(contour, axis=0).max() * POLYGON_APPROX_TOLERANCE,
- )
- polygon = np.clip(polygon, (0, 0), (mask.shape[0] - 1, mask.shape[1] - 1))
- polygon = polygon[:-1] # drop last point that is duplicate of first point
- if 0:
- import PIL.Image
- image_pil = PIL.Image.fromarray(imgviz.gray2rgb(imgviz.bool2ubyte(mask)))
- imgviz.draw.line_(image_pil, yx=polygon, fill=(0, 255, 0))
- for point in polygon:
- imgviz.draw.circle_(image_pil, center=point, diameter=10, fill=(0, 255, 0))
- imgviz.io.imsave("contour.jpg", np.asarray(image_pil))
- return polygon[:, ::-1] # yx -> xy
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