Question

我通过从here下载的FMM工具计算铁路网络中两个城市之间的最短路径。但它无法获得对称距离（从城市A到城市B的距离不等于从城市B到城市A的距离）。在以下M代码中交换pointA和pointB来测试此问题。网络文件是1012 * 1564像素的图像。下载链接看到我的评论（我不能发布两个链接）。

我的问题：

1如何获得对称距离。

2距离的单位是多少？是重量/像素吗？

% Read the network
image_rail = imread('railroad.png');
rail = (double(image_rail(:,:,1)==0));
% 90 on the rail road and 0.0001 off road
weight = 90;
SpeedImage = rail*weight+0.0001;

% Get the path
path(path,'toolbox/FastMarching_version3b');

% Location of two cities
pointA= [609;1089];
pointB = [744;1141];

% Calculate the distance map (distance to pointA)
DistanceMap= msfm(SpeedImage, pointA);

% The distance between two cities
distance_between_2cities = DistanceMap(pointB(1),pointB(2))

% Tracing the shortest path from start point to source point using distance map.
ShortestLine=shortestpath(DistanceMap,pointB,pointA);

% Show the map
rgb_rail = ones(size(rail));
rgb_rail (rail == 1)= 0.1;
imshow(rgb_rail) % Test for railroad and road matrix

% Plot the shortest route
hold on, plot(ShortestLine(:,2),ShortestLine(:,1),'r');

% Plote the pointB and pointA
plot(pointB(2),pointB(1),'.','MarkerSize',30,'color','blue');
plot(pointA(2),pointA(1),'.','MarkerSize',30,'color','red');

enter image description here

通过FMM计算最短路径

0 个答案: