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from __future__ import division |
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import numpy as np |
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from annotator.uniformer.mmcv.image import rgb2bgr |
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from annotator.uniformer.mmcv.video import flowread |
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from .image import imshow |
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def flowshow(flow, win_name='', wait_time=0): |
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"""Show optical flow. |
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Args: |
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flow (ndarray or str): The optical flow to be displayed. |
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win_name (str): The window name. |
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wait_time (int): Value of waitKey param. |
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""" |
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flow = flowread(flow) |
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flow_img = flow2rgb(flow) |
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imshow(rgb2bgr(flow_img), win_name, wait_time) |
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def flow2rgb(flow, color_wheel=None, unknown_thr=1e6): |
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"""Convert flow map to RGB image. |
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Args: |
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flow (ndarray): Array of optical flow. |
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color_wheel (ndarray or None): Color wheel used to map flow field to |
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RGB colorspace. Default color wheel will be used if not specified. |
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unknown_thr (str): Values above this threshold will be marked as |
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unknown and thus ignored. |
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Returns: |
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ndarray: RGB image that can be visualized. |
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""" |
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assert flow.ndim == 3 and flow.shape[-1] == 2 |
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if color_wheel is None: |
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color_wheel = make_color_wheel() |
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assert color_wheel.ndim == 2 and color_wheel.shape[1] == 3 |
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num_bins = color_wheel.shape[0] |
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dx = flow[:, :, 0].copy() |
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dy = flow[:, :, 1].copy() |
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ignore_inds = ( |
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np.isnan(dx) | np.isnan(dy) | (np.abs(dx) > unknown_thr) | |
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(np.abs(dy) > unknown_thr)) |
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dx[ignore_inds] = 0 |
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dy[ignore_inds] = 0 |
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rad = np.sqrt(dx**2 + dy**2) |
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if np.any(rad > np.finfo(float).eps): |
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max_rad = np.max(rad) |
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dx /= max_rad |
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dy /= max_rad |
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rad = np.sqrt(dx**2 + dy**2) |
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angle = np.arctan2(-dy, -dx) / np.pi |
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bin_real = (angle + 1) / 2 * (num_bins - 1) |
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bin_left = np.floor(bin_real).astype(int) |
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bin_right = (bin_left + 1) % num_bins |
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w = (bin_real - bin_left.astype(np.float32))[..., None] |
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flow_img = (1 - |
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w) * color_wheel[bin_left, :] + w * color_wheel[bin_right, :] |
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small_ind = rad <= 1 |
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flow_img[small_ind] = 1 - rad[small_ind, None] * (1 - flow_img[small_ind]) |
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flow_img[np.logical_not(small_ind)] *= 0.75 |
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flow_img[ignore_inds, :] = 0 |
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return flow_img |
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def make_color_wheel(bins=None): |
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"""Build a color wheel. |
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Args: |
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bins(list or tuple, optional): Specify the number of bins for each |
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color range, corresponding to six ranges: red -> yellow, |
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yellow -> green, green -> cyan, cyan -> blue, blue -> magenta, |
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magenta -> red. [15, 6, 4, 11, 13, 6] is used for default |
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(see Middlebury). |
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Returns: |
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ndarray: Color wheel of shape (total_bins, 3). |
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""" |
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if bins is None: |
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bins = [15, 6, 4, 11, 13, 6] |
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assert len(bins) == 6 |
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RY, YG, GC, CB, BM, MR = tuple(bins) |
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ry = [1, np.arange(RY) / RY, 0] |
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yg = [1 - np.arange(YG) / YG, 1, 0] |
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gc = [0, 1, np.arange(GC) / GC] |
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cb = [0, 1 - np.arange(CB) / CB, 1] |
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bm = [np.arange(BM) / BM, 0, 1] |
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mr = [1, 0, 1 - np.arange(MR) / MR] |
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num_bins = RY + YG + GC + CB + BM + MR |
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color_wheel = np.zeros((3, num_bins), dtype=np.float32) |
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col = 0 |
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for i, color in enumerate([ry, yg, gc, cb, bm, mr]): |
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for j in range(3): |
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color_wheel[j, col:col + bins[i]] = color[j] |
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col += bins[i] |
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return color_wheel.T |
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