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"""
the blender script to get the camera intrinsic matrix
"""
import bpy
import numpy as np
def get_calibration_matrix_K_from_blender(mode='simple'):
scene = bpy.context.scene
scale = scene.render.resolution_percentage / 100
width = scene.render.resolution_x * scale # px
height = scene.render.resolution_y * scale # px
camdata = scene.camera.data
if mode == 'simple':
aspect_ratio = width / height
K = np.zeros((3,3), dtype=np.float32)
K[0][0] = width / 2 / np.tan(camdata.angle / 2)
K[1][1] = height / 2. / np.tan(camdata.angle / 2) * aspect_ratio
K[0][2] = width / 2.
K[1][2] = height / 2.
K[2][2] = 1.
K.transpose()
if mode == 'complete':
focal = camdata.lens # mm
sensor_width = camdata.sensor_width # mm
sensor_height = camdata.sensor_height # mm
pixel_aspect_ratio = scene.render.pixel_aspect_x / scene.render.pixel_aspect_y
if (camdata.sensor_fit == 'VERTICAL'):
# the sensor height is fixed (sensor fit is horizontal),
# the sensor width is effectively changed with the pixel aspect ratio
s_u = width / sensor_width / pixel_aspect_ratio
s_v = height / sensor_height
else: # 'HORIZONTAL' and 'AUTO'
# the sensor width is fixed (sensor fit is horizontal),
# the sensor height is effectively changed with the pixel aspect ratio
pixel_aspect_ratio = scene.render.pixel_aspect_x / scene.render.pixel_aspect_y
s_u = width / sensor_width
s_v = height * pixel_aspect_ratio / sensor_height
# parameters of intrinsic calibration matrix K
alpha_u = focal * s_u
alpha_v = focal * s_v
u_0 = width / 2
v_0 = height / 2
skew = 0 # only use rectangular pixels
K = np.array([
[alpha_u, skew, u_0],
[ 0, alpha_v, v_0],
[ 0, 0, 1]
], dtype=np.float32)
return K
K = get_calibration_matrix_K_from_blender('complete')
np.savetxt('./camera_para.txt', K) |