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Open Source Computer Vision Library
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85 lines
3.5 KiB
85 lines
3.5 KiB
#!/usr/bin/env python |
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''' |
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This sample using FlowNet v2 model to calculate optical flow. |
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Original paper: https://arxiv.org/abs/1612.01925. |
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Original repo: https://github.com/lmb-freiburg/flownet2. |
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Download the converted .caffemodel model from https://drive.google.com/open?id=16qvE9VNmU39NttpZwZs81Ga8VYQJDaWZ |
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and .prototxt from https://drive.google.com/open?id=19bo6SWU2p8ZKvjXqMKiCPdK8mghwDy9b. |
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Otherwise download original model from https://lmb.informatik.uni-freiburg.de/resources/binaries/flownet2/flownet2-models.tar.gz, |
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convert .h5 model to .caffemodel and modify original .prototxt using .prototxt from link above. |
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''' |
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import argparse |
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import os.path |
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import numpy as np |
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import cv2 as cv |
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class OpticalFlow(object): |
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def __init__(self, proto, model, height, width): |
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self.net = cv.dnn.readNet(proto, model) |
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self.net.setPreferableBackend(cv.dnn.DNN_BACKEND_OPENCV) |
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self.height = height |
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self.width = width |
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def compute_flow(self, first_img, second_img): |
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inp0 = cv.dnn.blobFromImage(first_img, size=(self.width, self.height)) |
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inp1 = cv.dnn.blobFromImage(second_img, size=(self.width, self.height)) |
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self.net.setInput(inp0, "img0") |
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self.net.setInput(inp1, "img1") |
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flow = self.net.forward() |
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output = self.motion_to_color(flow) |
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return output |
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def motion_to_color(self, flow): |
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arr = np.arange(0, 255, dtype=np.uint8) |
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colormap = cv.applyColorMap(arr, cv.COLORMAP_HSV) |
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colormap = colormap.squeeze(1) |
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flow = flow.squeeze(0) |
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fx, fy = flow[0, ...], flow[1, ...] |
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rad = np.sqrt(fx**2 + fy**2) |
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maxrad = rad.max() if rad.max() != 0 else 1 |
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ncols = arr.size |
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rad = rad[..., np.newaxis] / maxrad |
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a = np.arctan2(-fy / maxrad, -fx / maxrad) / np.pi |
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fk = (a + 1) / 2.0 * (ncols - 1) |
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k0 = fk.astype(np.int) |
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k1 = (k0 + 1) % ncols |
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f = fk[..., np.newaxis] - k0[..., np.newaxis] |
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col0 = colormap[k0] / 255.0 |
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col1 = colormap[k1] / 255.0 |
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col = (1 - f) * col0 + f * col1 |
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col = np.where(rad <= 1, 1 - rad * (1 - col), col * 0.75) |
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output = (255.0 * col).astype(np.uint8) |
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return output |
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if __name__ == '__main__': |
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parser = argparse.ArgumentParser(description='Use this script to calculate optical flow using FlowNetv2', |
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formatter_class=argparse.ArgumentDefaultsHelpFormatter) |
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parser.add_argument('-input', '-i', required=True, help='Path to input video file. Skip this argument to capture frames from a camera.') |
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parser.add_argument('--height', default=320, help='Input height') |
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parser.add_argument('--width', default=448, help='Input width') |
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parser.add_argument('--proto', '-p', default='FlowNet2_deploy.prototxt', help='Path to prototxt.') |
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parser.add_argument('--model', '-m', default='FlowNet2_weights.caffemodel', help='Path to caffemodel.') |
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args, _ = parser.parse_known_args() |
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if not os.path.isfile(args.model) or not os.path.isfile(args.proto): |
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raise OSError("Prototxt or caffemodel not exist") |
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winName = 'Calculation optical flow in OpenCV' |
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cv.namedWindow(winName, cv.WINDOW_NORMAL) |
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cap = cv.VideoCapture(args.input if args.input else 0) |
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hasFrame, first_frame = cap.read() |
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opt_flow = OpticalFlow(args.proto, args.model, args.height, args.width) |
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while cv.waitKey(1) < 0: |
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hasFrame, second_frame = cap.read() |
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if not hasFrame: |
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break |
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flow = opt_flow.compute_flow(first_frame, second_frame) |
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first_frame = second_frame |
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cv.imshow(winName, flow)
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