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| import torch | |
| import numpy as np | |
| def generate_spiral_trajectory(num_frames, radius, forward_ratio=0.2, backward_ratio=0.8): | |
| t = np.linspace(0, 1, num_frames) | |
| r = np.sin(2 * np.pi * t) * radius | |
| # rotation angles at each frame | |
| theta = 2 * np.pi * t * num_frames | |
| # try not to change y (up-down for floor and sky) | |
| x = r * np.cos(theta) | |
| y = r * np.sin(theta) * 0.3 | |
| z = -r | |
| z[z<0]*=forward_ratio | |
| z[z>0]*=backward_ratio | |
| return x, y, z | |
| def look_at(camera_position, target_position): | |
| # look at direction | |
| direction = target_position - camera_position | |
| direction /= np.linalg.norm(direction) | |
| # calculate rotation matrix | |
| up = np.array([0, 1, 0]) | |
| right = np.cross(up, direction) | |
| right /= np.linalg.norm(right) | |
| up = np.cross(direction, right) | |
| rotation_matrix = np.vstack([right, up, direction]) | |
| rotation_matrix = np.linalg.inv(rotation_matrix) | |
| return rotation_matrix | |
| def spiral_camera_poses(num_frames, radius, forward_ratio = 0.2, backward_ratio = 0.8, rotation_times = 0.3, look_at_times = 0.5): | |
| x, y, z = generate_spiral_trajectory(num_frames, radius*rotation_times, forward_ratio, backward_ratio) | |
| target_position = np.array([0,0,radius*look_at_times]) | |
| camera_positions = np.vstack([x, y, z]).T | |
| camera_poses = [] | |
| for pos in camera_positions: | |
| rotation_matrix = look_at(pos, target_position) | |
| transform_matrix = np.eye(4) | |
| transform_matrix[:3, :3] = rotation_matrix | |
| transform_matrix[:3, 3] = pos | |
| camera_poses.append(transform_matrix[None]) | |
| camera_poses.reverse() | |
| camera_poses = np.concatenate(camera_poses,axis=0) | |
| return camera_poses |