我正在为体素渲染编写一个贪婪的网格算法，其中很大一部分是找到体积的边缘。我通过旋转体积阵列来做到这一点。然后使用 Scipy 的 Ndimage 将其与 3d 边缘检测内核进行卷积。我基本上是在z方向使用清醒的方法。这应该给我垂直于当前扫描轴的二维横截面。但是，当体积数组未完全填充时，我遇到了问题：由于某种原因，当只有一个边缘时，输出给出了两个边缘。这两个都是正面的方向。
请注意，我使用正 1 或负 1 来跟踪边缘所面对的方向。所有面都是来自任何轴的 90 * 孔整数。
我的问题如下。如何使用卷积检测垂直于 z 轴的 3d 体积阵列中的边缘？我应该使用什么样的内核？有没有其他更好的方法？
import numpy as np
from scipy import ndimage
# defines the shape of the array
isls = 8
rows = 8
clos = 8
itrater = 0
field = []
for z in range(isls):
field.append([])
for y in range(rows):
field[z].append([])
for x in range(clos):
itrater += 1
# to methods for filling the array
# first method fills array all with 1, it is commented out
# field[z][y].append(1)
# second method
# fills it with a box of ones that is slightly smaller than the full array
field[z][y].append((z<7)*(x<7)*(y<7)*1)
# wighted array for edge detection
k1 = np.array([[[-0,-0,-0],
[-0,-1,-0],
[-0,-0,-0]],
[[ 0, 0, 0],
[ 0, 0, 0],
[ 0, 0, 0]],
[[ 0, 0, 0],
[ 0, 1, 0],
[ 0, 0, 0]]])
# convoleds the field array with k1. Also, values outside of the array are set to 0.0
workingGride = ndimage.convolve(field, k1, mode='constant')
# when the array is not completely filled
# The output gives two edges with postive 1, given tree edges totally,
# when really there should only be two sides laying flat when you going up and down the z-axis of the cube
#postive or negative ones represent facing direction.
workingGride
这是出局
array([[[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[-1, -1, -1, -1, -1, -1, -1, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]],
[[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 1, 1, 1, 1, 1, 1, 1, 0],
[ 0, 0, 0, 0, 0, 0, 0, 0]]])
# the last one should be filled with 0