我已经把一个立体声凸轮装置放在一起,我很难用它来制作一个好的视差图 . 这是一个两个校正图像和我用它们产生的视差图的例子:
如你所见,结果非常糟糕 . 更改StereoBM的设置并没有太大变化 .
The setup
-
两台相机都是同型号,并通过USB连接到我的电脑 .
-
它们固定在坚硬的木板上,因此它们并不完美 . 它们无法移动,因此它们在校准期间和之后的位置是相同的 .
-
我使用OpenCV校准了立体声对,并使用OpenCV的
StereoBM
类来生成视差图 . -
它's probably not that relevant, but I'用Python编码 .
Problems I could imagine
我'm doing this for the first time, so I'远非专家,但我已经尝试了 StereoBM
的所有设置排列,虽然我得到了不同的结果,但它们都像上面显示的视差图:黑色和白色的补丁 .
正如我所理解的那样,立体校正应该对齐每个图像上的所有点,以便它们通过直线(在我的情况下是水平线)连接,这一事实进一步支持了这一想法 . 如果我检查彼此相邻的两个经过校正的图片,那么事实并非如此,事实并非如此 . 右侧图片上的对应点比左侧高得多 . 不过,我不确定校准或整流是否是问题 .
The code
实际代码包含在对象中 - 如果你're interested in seeing it in its entirety, it'可用on GitHub . 这是一个实际运行的简化示例(当然在我使用超过2张图片校准的实际代码中):
import cv2
import numpy as np
## Load test images
# TEST_IMAGES is a list of paths to test images
input_l, input_r = [cv2.imread(image, cv2.CV_LOAD_IMAGE_GRAYSCALE)
for image in TEST_IMAGES]
image_size = input_l.shape[:2]
## Retrieve chessboard corners
# CHESSBOARD_ROWS and CHESSBOARD_COLUMNS are the number of inside rows and
# columns in the chessboard used for calibration
pattern_size = CHESSBOARD_ROWS, CHESSBOARD_COLUMNS
object_points = np.zeros((np.prod(pattern_size), 3), np.float32)
object_points[:, :2] = np.indices(pattern_size).T.reshape(-1, 2)
# SQUARE_SIZE is the size of the chessboard squares in cm
object_points *= SQUARE_SIZE
image_points = {}
ret, corners_l = cv2.findChessboardCorners(input_l, pattern_size, True)
cv2.cornerSubPix(input_l, corners_l,
(11, 11), (-1, -1),
(cv2.TERM_CRITERIA_MAX_ITER + cv2.TERM_CRITERIA_EPS,
30, 0.01))
image_points["left"] = corners_l.reshape(-1, 2)
ret, corners_r = cv2.findChessboardCorners(input_r, pattern_size, True)
cv2.cornerSubPix(input_r, corners_r,
(11, 11), (-1, -1),
(cv2.TERM_CRITERIA_MAX_ITER + cv2.TERM_CRITERIA_EPS,
30, 0.01))
image_points["right"] = corners_r.reshape(-1, 2)
## Calibrate cameras
(cam_mats, dist_coefs, rect_trans, proj_mats, valid_boxes,
undistortion_maps, rectification_maps) = {}, {}, {}, {}, {}, {}, {}
criteria = (cv2.TERM_CRITERIA_MAX_ITER + cv2.TERM_CRITERIA_EPS,
100, 1e-5)
flags = (cv2.CALIB_FIX_ASPECT_RATIO + cv2.CALIB_ZERO_TANGENT_DIST +
cv2.CALIB_SAME_FOCAL_LENGTH)
(ret, cam_mats["left"], dist_coefs["left"], cam_mats["right"],
dist_coefs["right"], rot_mat, trans_vec, e_mat,
f_mat) = cv2.stereoCalibrate(object_points,
image_points["left"], image_points["right"],
image_size, criteria=criteria, flags=flags)
(rect_trans["left"], rect_trans["right"],
proj_mats["left"], proj_mats["right"],
disp_to_depth_mat, valid_boxes["left"],
valid_boxes["right"]) = cv2.stereoRectify(cam_mats["left"],
dist_coefs["left"],
cam_mats["right"],
dist_coefs["right"],
image_size,
rot_mat, trans_vec, flags=0)
for side in ("left", "right"):
(undistortion_maps[side],
rectification_maps[side]) = cv2.initUndistortRectifyMap(cam_mats[side],
dist_coefs[side],
rect_trans[side],
proj_mats[side],
image_size,
cv2.CV_32FC1)
## Produce disparity map
rectified_l = cv2.remap(input_l, undistortion_maps["left"],
rectification_maps["left"],
cv2.INTER_NEAREST)
rectified_r = cv2.remap(input_r, undistortion_maps["right"],
rectification_maps["right"],
cv2.INTER_NEAREST)
cv2.imshow("left", rectified_l)
cv2.imshow("right", rectified_r)
block_matcher = cv2.StereoBM(cv2.STEREO_BM_BASIC_PRESET, 0, 5)
disp = block_matcher.compute(rectified_l, rectified_r, disptype=cv2.CV_32F)
cv2.imshow("disparity", disp)
这里出了什么问题?
1 回答
原来,问题是可视化而不是数据本身 . 在某处我读到
cv2.reprojectImageTo3D
需要一个视差图作为浮点值,这就是我从block_matcher.compute
请求cv2.CV_32F
的原因 .更仔细地阅读OpenCV文档让我觉得我错误地认为这是错误的,并且为了速度,我实际上喜欢使用整数而不是浮点数,但是
cv2.imshow
的文档不是't clear on what it does with 16 bit signed integers (as compared to 16 bit unsigned), so for the visualization I' m将值保留为浮点数 .documentation of cv2.imshow显示32位浮点值假设在0和1之间,所以它们是一个可怕的操作,但我只是为了调整我的
StereoBM
离线,所以性能是不加批判的 . 解决方案如下所示:然后视差图看起来没问题 .