我正在制作一个程序,可以找到图像上两点之间的路径(很快就会成为视频帧)。我所做的是使用多边形对象来识别路径之间的障碍物,并使用该多边形对象根据需要绕过。我的代码如下:
simplepoint = tuple[int, int]
def getpolygonsinway(start: simplepoint, end: simplepoint, polygons: list[polygon]) -> list[polygon]:
line = linestring([start, end])
polygonsinway = [polygon for polygon in polygons if line.crosses(polygon)] # make sure line.crosses() doesnt return true if the starting point is on the polygon
return polygonsinway
def getpaths(start: simplepoint, end: simplepoint, polygons: list[polygon], prev_points: list[simplepoint] = []) -> list[list[simplepoint]]:
polygonsinway = getpolygonsinway(start, end, polygons)
if not polygonsinway:
return [[start, end]]
closestpolygon = closestpolygontopoint(start, polygons)
xyvalsold = closestpolygon.exterior.xy
xyvals = []
for i in range(len(xyvalsold[0])):
xyvals.append((xyvalsold[0][i], xyvalsold[1][i]))
xyvals = list(set(xyvals)) # remove duplicates
polxvals = [val[0] for val in xyvals]
polyvals = [val[1] for val in xyvals]
okpoints = []
for i in range(len(polxvals)):
if start == (polxvals[i], polyvals[i]):
continue
if int(polxvals[i]) != polxvals[i] or int(polyvals[i]) != polyvals[i]:
continue
if (int(polxvals[i]), int(polyvals[i])) in prev_points:
continue
if closestpolygon not in getpolygonsinway(start, (polxvals[i], polyvals[i]), polygons): #and closestpolygon not in getpolygonsinway((polxvals[i], polyvals[i]), end, polygons):
okpoints.append((int(polxvals[i]), int(polyvals[i])))
paths = [[start] for _ in range(len(okpoints))]
for i in range(len(okpoints)):
point = (okpoints[i][0], okpoints[i][1])
paths[i].extend(getshortestpath(getpaths(point, end, polygons, prev_points + [point]), point, end))
return paths
目前,我使用的唯一障碍是简单的形状,例如矩形、正方形、圆形等,一旦一切正常,我将改用视频。当两个部分是矩形的对角线时,函数 getpolygonsinway
中的列表理解中的 line.crosses(polygon)
返回 false 时,会出现问题。我已经查看了文档,但我不知道用什么来确保我正确地捕获这个案例,所以我在这里问了这个问题。
编辑:根据要求,示例多边形、起点和终点如下:
polygon = Polygon([[411, 182], [411, 335], [210, 335], [210, 182]])
start = (440, 35)
end = (90, 600)
使用上面的代码,运行 getshortestpath(getpaths(start, end, polygons, []))
后得到以下路径:
[(440, 35), (411, 182), (210, 335), (90, 600)]
正确答案
我找到了 line.within(polygon)
方法,该方法检查该线是否位于传递的多边形内部。我不知道为什么我以前没有看到它,但现在我看到了。通过在列表理解 if 条件中执行 line.crosses(polygon) 或 line.within(polygon)
,我设法获得了围绕矩形的路径。我现在将使用其他基本形状来测试它,然后无限地测试它的用途。