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# This file is modified from NeRF++: https://github.com/Kai-46/nerfplusplus | |
import numpy as np | |
try: | |
import open3d as o3d | |
except ImportError: | |
pass | |
def frustums2lineset(frustums): | |
N = len(frustums) | |
merged_points = np.zeros((N*5, 3)) # 5 vertices per frustum | |
merged_lines = np.zeros((N*8, 2)) # 8 lines per frustum | |
merged_colors = np.zeros((N*8, 3)) # each line gets a color | |
for i, (frustum_points, frustum_lines, frustum_colors) in enumerate(frustums): | |
merged_points[i*5:(i+1)*5, :] = frustum_points | |
merged_lines[i*8:(i+1)*8, :] = frustum_lines + i*5 | |
merged_colors[i*8:(i+1)*8, :] = frustum_colors | |
lineset = o3d.geometry.LineSet() | |
lineset.points = o3d.utility.Vector3dVector(merged_points) | |
lineset.lines = o3d.utility.Vector2iVector(merged_lines) | |
lineset.colors = o3d.utility.Vector3dVector(merged_colors) | |
return lineset | |
def get_camera_frustum_opengl_coord(H, W, fx, fy, W2C, frustum_length=0.5, color=np.array([0., 1., 0.])): | |
'''X right, Y up, Z backward to the observer. | |
:param H, W: | |
:param fx, fy: | |
:param W2C: (4, 4) matrix | |
:param frustum_length: scalar: scale the frustum | |
:param color: (3,) list, frustum line color | |
:return: | |
frustum_points: (5, 3) frustum points in world coordinate | |
frustum_lines: (8, 2) 8 lines connect 5 frustum points, specified in line start/end index. | |
frustum_colors: (8, 3) colors for 8 lines. | |
''' | |
hfov = np.rad2deg(np.arctan(W / 2. / fx) * 2.) | |
vfov = np.rad2deg(np.arctan(H / 2. / fy) * 2.) | |
half_w = frustum_length * np.tan(np.deg2rad(hfov / 2.)) | |
half_h = frustum_length * np.tan(np.deg2rad(vfov / 2.)) | |
# build view frustum in camera space in homogenous coordinate (5, 4) | |
frustum_points = np.array([[0., 0., 0., 1.0], # frustum origin | |
[-half_w, half_h, -frustum_length, 1.0], # top-left image corner | |
[half_w, half_h, -frustum_length, 1.0], # top-right image corner | |
[half_w, -half_h, -frustum_length, 1.0], # bottom-right image corner | |
[-half_w, -half_h, -frustum_length, 1.0]]) # bottom-left image corner | |
frustum_lines = np.array([[0, i] for i in range(1, 5)] + [[i, (i+1)] for i in range(1, 4)] + [[4, 1]]) # (8, 2) | |
frustum_colors = np.tile(color.reshape((1, 3)), (frustum_lines.shape[0], 1)) # (8, 3) | |
# transform view frustum from camera space to world space | |
C2W = np.linalg.inv(W2C) | |
frustum_points = np.matmul(C2W, frustum_points.T).T # (5, 4) | |
frustum_points = frustum_points[:, :3] / frustum_points[:, 3:4] # (5, 3) remove homogenous coordinate | |
return frustum_points, frustum_lines, frustum_colors | |
def get_camera_frustum_opencv_coord(H, W, fx, fy, W2C, frustum_length=0.5, color=np.array([0., 1., 0.])): | |
'''X right, Y up, Z backward to the observer. | |
:param H, W: | |
:param fx, fy: | |
:param W2C: (4, 4) matrix | |
:param frustum_length: scalar: scale the frustum | |
:param color: (3,) list, frustum line color | |
:return: | |
frustum_points: (5, 3) frustum points in world coordinate | |
frustum_lines: (8, 2) 8 lines connect 5 frustum points, specified in line start/end index. | |
frustum_colors: (8, 3) colors for 8 lines. | |
''' | |
hfov = np.rad2deg(np.arctan(W / 2. / fx) * 2.) | |
vfov = np.rad2deg(np.arctan(H / 2. / fy) * 2.) | |
half_w = frustum_length * np.tan(np.deg2rad(hfov / 2.)) | |
half_h = frustum_length * np.tan(np.deg2rad(vfov / 2.)) | |
# build view frustum in camera space in homogenous coordinate (5, 4) | |
frustum_points = np.array([[0., 0., 0., 1.0], # frustum origin | |
[-half_w, -half_h, frustum_length, 1.0], # top-left image corner | |
[ half_w, -half_h, frustum_length, 1.0], # top-right image corner | |
[ half_w, half_h, frustum_length, 1.0], # bottom-right image corner | |
[-half_w, +half_h, frustum_length, 1.0]]) # bottom-left image corner | |
frustum_lines = np.array([[0, i] for i in range(1, 5)] + [[i, (i+1)] for i in range(1, 4)] + [[4, 1]]) # (8, 2) | |
frustum_colors = np.tile(color.reshape((1, 3)), (frustum_lines.shape[0], 1)) # (8, 3) | |
# transform view frustum from camera space to world space | |
C2W = np.linalg.inv(W2C) | |
frustum_points = np.matmul(C2W, frustum_points.T).T # (5, 4) | |
frustum_points = frustum_points[:, :3] / frustum_points[:, 3:4] # (5, 3) remove homogenous coordinate | |
return frustum_points, frustum_lines, frustum_colors | |
def draw_camera_frustum_geometry(c2ws, H, W, fx=600.0, fy=600.0, frustum_length=0.5, | |
color=np.array([29.0, 53.0, 87.0])/255.0, draw_now=False, coord='opengl'): | |
''' | |
:param c2ws: (N, 4, 4) np.array | |
:param H: scalar | |
:param W: scalar | |
:param fx: scalar | |
:param fy: scalar | |
:param frustum_length: scalar | |
:param color: None or (N, 3) or (3, ) or (1, 3) or (3, 1) np array | |
:param draw_now: True/False call o3d vis now | |
:return: | |
''' | |
N = c2ws.shape[0] | |
num_ele = color.flatten().shape[0] | |
if num_ele == 3: | |
color = color.reshape(1, 3) | |
color = np.tile(color, (N, 1)) | |
frustum_list = [] | |
if coord == 'opengl': | |
for i in range(N): | |
frustum_list.append(get_camera_frustum_opengl_coord(H, W, fx, fy, | |
W2C=np.linalg.inv(c2ws[i]), | |
frustum_length=frustum_length, | |
color=color[i])) | |
elif coord == 'opencv': | |
for i in range(N): | |
frustum_list.append(get_camera_frustum_opencv_coord(H, W, fx, fy, | |
W2C=np.linalg.inv(c2ws[i]), | |
frustum_length=frustum_length, | |
color=color[i])) | |
else: | |
print('Undefined coordinate system. Exit') | |
exit() | |
frustums_geometry = frustums2lineset(frustum_list) | |
if draw_now: | |
o3d.visualization.draw_geometries([frustums_geometry]) | |
return frustums_geometry # this is an o3d geometry object. | |