projet-probleme-inverse-3D/get_proj.py
2023-01-13 09:00:44 +01:00

145 lines
4.9 KiB
Python

# https://blender.stackexchange.com/questions/38009/3x4-camera-matrix-from-blender-camera
import bpy
from mathutils import Matrix
import pickle
import numpy as np
#---------------------------------------------------------------
# 3x4 P matrix from Blender camera
#---------------------------------------------------------------
# BKE_camera_sensor_size
def get_sensor_size(sensor_fit, sensor_x, sensor_y):
if sensor_fit == 'VERTICAL':
return sensor_y
return sensor_x
# BKE_camera_sensor_fit
def get_sensor_fit(sensor_fit, size_x, size_y):
if sensor_fit == 'AUTO':
if size_x >= size_y:
return 'HORIZONTAL'
else:
return 'VERTICAL'
return sensor_fit
# Build intrinsic camera parameters from Blender camera data
#
# See notes on this in
# blender.stackexchange.com/questions/15102/what-is-blenders-camera-projection-matrix-model
# as well as
# https://blender.stackexchange.com/a/120063/3581
def get_calibration_matrix_K_from_blender(camd):
if camd.type != 'PERSP':
raise ValueError('Non-perspective cameras not supported')
scene = bpy.context.scene
f_in_mm = camd.lens
scale = scene.render.resolution_percentage / 100
resolution_x_in_px = scale * scene.render.resolution_x
resolution_y_in_px = scale * scene.render.resolution_y
sensor_size_in_mm = get_sensor_size(camd.sensor_fit, camd.sensor_width, camd.sensor_height)
sensor_fit = get_sensor_fit(
camd.sensor_fit,
scene.render.pixel_aspect_x * resolution_x_in_px,
scene.render.pixel_aspect_y * resolution_y_in_px
)
pixel_aspect_ratio = scene.render.pixel_aspect_y / scene.render.pixel_aspect_x
if sensor_fit == 'HORIZONTAL':
view_fac_in_px = resolution_x_in_px
else:
view_fac_in_px = pixel_aspect_ratio * resolution_y_in_px
pixel_size_mm_per_px = sensor_size_in_mm / f_in_mm / view_fac_in_px
s_u = 1 / pixel_size_mm_per_px
s_v = 1 / pixel_size_mm_per_px / pixel_aspect_ratio
# Parameters of intrinsic calibration matrix K
u_0 = resolution_x_in_px / 2 - camd.shift_x * view_fac_in_px
v_0 = resolution_y_in_px / 2 + camd.shift_y * view_fac_in_px / pixel_aspect_ratio
skew = 0 # only use rectangular pixels
K = Matrix(
((s_u, skew, u_0),
( 0, s_v, v_0),
( 0, 0, 1)))
return K
# Returns camera rotation and translation matrices from Blender.
#
# There are 3 coordinate systems involved:
# 1. The World coordinates: "world"
# - right-handed
# 2. The Blender camera coordinates: "bcam"
# - x is horizontal
# - y is up
# - right-handed: negative z look-at direction
# 3. The desired computer vision camera coordinates: "cv"
# - x is horizontal
# - y is down (to align to the actual pixel coordinates
# used in digital images)
# - right-handed: positive z look-at direction
def get_3x4_RT_matrix_from_blender(cam):
# bcam stands for blender camera
R_bcam2cv = Matrix(
((1, 0, 0),
(0, -1, 0),
(0, 0, -1)))
# Transpose since the rotation is object rotation,
# and we want coordinate rotation
# R_world2bcam = cam.rotation_euler.to_matrix().transposed()
# T_world2bcam = -1*R_world2bcam @ location
#
# Use matrix_world instead to account for all constraints
location, rotation = cam.matrix_world.decompose()[0:2]
R_world2bcam = rotation.to_matrix().transposed()
# Convert camera location to translation vector used in coordinate changes
# T_world2bcam = -1*R_world2bcam @ cam.location
# Use location from matrix_world to account for constraints:
T_world2bcam = -1*R_world2bcam @ location
# Build the coordinate transform matrix from world to computer vision camera
R_world2cv = R_bcam2cv@R_world2bcam
T_world2cv = R_bcam2cv@T_world2bcam
# put into 3x4 matrix
RT = Matrix((
R_world2cv[0][:] + (T_world2cv[0],),
R_world2cv[1][:] + (T_world2cv[1],),
R_world2cv[2][:] + (T_world2cv[2],)
))
return RT
def get_3x4_P_matrix_from_blender(cam):
K = get_calibration_matrix_K_from_blender(cam.data)
RT = get_3x4_RT_matrix_from_blender(cam)
return K@RT, K, RT
def run_script(scene):
with open(PICKLE_PATH, 'rb') as file:
matrices = pickle.load(file)
projection_matrix, _, _ = get_3x4_P_matrix_from_blender(scene.camera)
matrices.append(np.array(projection_matrix))
with open(PICKLE_PATH, 'wb') as file:
pickle.dump(matrices, file)
def setup_script(scene):
matrices = []
with open(PICKLE_PATH, 'wb') as file:
pickle.dump(matrices, file)
PICKLE_PATH = "/tmp/pickle.truc"
# clear handlers
bpy.app.handlers.render_init.clear()
bpy.app.handlers.frame_change_pre.clear()
bpy.app.handlers.frame_change_post.clear()
# add handler
bpy.app.handlers.render_init.append(setup_script)
bpy.app.handlers.frame_change_post.append(run_script)