通过计算两个不同形状的距离获得形状上下文错误 [英] Shape Context Error by calculating distance of two different shapes
问题描述
简而言之，我想通过形状上下文"匹配来比较不同的道路标记.
In short form, I want to compare different road markings by "shape context" matching.
我的第一个问题可以在下面看到:从OpenData匹配道路标记的形状
My first question you can see under: Matching shapes of road marking from OpenData
我解决了第一个问题，但现在出现了一个新错误.这是我的代码:
I solved my first problem, but now it appears a new error. Here is my code:
import cv2
import numpy as np
# read data
datapath = "/Users/output/test/";
a = cv2.imread(datapath+"template_orig.png");
b = cv2.imread(datapath+"template.png");
imgray_a = cv2.cvtColor(a,cv2.COLOR_BGR2GRAY)
ret_a,thresh_a = cv2.threshold(imgray_a,127,255,0)
imgray_b = cv2.cvtColor(b,cv2.COLOR_BGR2GRAY)
ret_b,thresh_b = cv2.threshold(imgray_b,127,255,0)
# find contours
_, ca, _ = cv2.findContours(thresh_a, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)
_, cb, _ = cv2.findContours(thresh_b, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)
print(np.shape(ca[0]), np.shape(cb[0]))
# generate distance --> Hausdorff OR ShapeContext
hd = cv2.createHausdorffDistanceExtractor()
sd = cv2.createShapeContextDistanceExtractor()
d1 = hd.computeDistance(ca[0],cb[0])
d2 = sd.computeDistance(ca[0],cb[0])
print(d1, " ", d2)
当我比较 a 时(原始转向箭头) 与 b (提取转向箭头)没有问题，但是当我比较 a 与 c (用于测试形状匹配"算法的其他方法)出现以下错误:
When I compare a (original turn arrow) with b (extracted turn arrow) there are no problems, but when I compare a with c (anything other to test "shape matching" algorithm) the following error appear:
OpenCV错误:gemImpl，文件/Users/travis/build/skvark/opencv-python/opencv/modules/core/src/matmul.cpp中的断言失败(类型== CV_64FC2)， 第1218行
OpenCV Error: Assertion failed (type == CV_64FC2) in gemmImpl, file /Users/travis/build/skvark/opencv-python/opencv/modules/core/src/matmul.cpp, line 1218
跟踪(最近一次通话最近):文件"/test_shape.py"，第74行，在 d2 = sd.computeDistance(ca [0]，cb [0])
Traceback (most recent call last): File "/test_shape.py", line 74, in d2 = sd.computeDistance(ca[0],cb[0])
cv2.error:/Users/travis/build/skvark/opencv-python/opencv/modules/core/src/matmul.cpp:1218: 错误:函数gemmImpl中(-215)类型== CV_64FC2
cv2.error: /Users/travis/build/skvark/opencv-python/opencv/modules/core/src/matmul.cpp:1218: error: (-215) type == CV_64FC2 in function gemmImpl
仅在生成形状上下文"距离的函数中发生错误，而不在生成"Hausdorff"距离的函数中发生
The error only occurs with the function of generating distance of "shape context" and not with the function of generating distance of "Hausdorff"
推荐答案
好吧，我认为问题是 a 和 b 或 a 和 c 的像素高度不同( a :131 x 32像素， b/c :29 x 18像素) .当我将 b 或 c 的图像尺寸更改为更高的分辨率(如131 x 81 px)时，错误消失了，并且正在计算形状上下文"的距离.
Ok, I think the problem was, that a and b or a and c don't have the same height of pixels (a: 131 x 32px, b / c: 29 x 18 px). When I change the size of the image of b or c to a higher resolution like 131 x 81 px the error disappear and the distance of "shape context" is being computed.
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