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[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin

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196 D. Cedrych et al.<br />

where<br />

, (6)<br />

,…, , , , , ,<br />

(7)<br />

, ∞, , 1,2,…,2<br />

In (7) and are equal to and correspond<strong>in</strong>gly which are def<strong>in</strong>ed <strong>in</strong><br />

(2). This set def<strong>in</strong>es the vertices of the graph (6). Second part of the graph model<br />

is the set of edges . It def<strong>in</strong>es mutual, spatial relations between elements def<strong>in</strong>ed<br />

by as well as costs of transitions between any given pair of vertices. Calculation<br />

of costs is a crucial part of the model creation. All the process of plann<strong>in</strong>g is based<br />

on the graph representation so the quality of the model is critical for this process.<br />

In this the cost between two elements of the set is calculated as:<br />

, 1 , (8)<br />

where denotes Euclidean distance between ith and jth vertex, and:<br />

<br />

, <br />

<br />

is a sum of altitudes read from the map (\ref{fig:2}) along the l<strong>in</strong>e that connects<br />

vertex ith with vertex jth. This mapp<strong>in</strong>g is done accord<strong>in</strong>g the follow<strong>in</strong>g rule:<br />

<br />

0 <br />

(10)<br />

, <br />

If the l<strong>in</strong>e that connects vertex ith with vertex jth crossed the state border l<strong>in</strong>e (9),<br />

the sum is set to a relatively big number to prevent the algorithm for search<strong>in</strong>g<br />

paths that crosses the border l<strong>in</strong>es. As a result of determ<strong>in</strong><strong>in</strong>g costs of transitions<br />

between all pairs of vertices the cost matrix is created. It is denoted as:<br />

2.6 Solution<br />

<br />

(9)<br />

, , 1,2,…,2 (11)<br />

For the representation given by (11) search<strong>in</strong>g the path of m<strong>in</strong>imal cost is performed.<br />

There are many effective algorithms for m<strong>in</strong>imal path search [5] but <strong>in</strong><br />

this study the Dijkstra's algorithm was chosen. S<strong>in</strong>ce the graph def<strong>in</strong>ed by (11) is<br />

the complete one, always exists the path connect<strong>in</strong>g vertices and .As a<br />

result of the graph search the path that connects those vertices is found:<br />

,…, , , , 2 2 (12)<br />

each element of the set (12) is a po<strong>in</strong>t <strong>in</strong> a 2D space. Next stage consists of transform<strong>in</strong>g<br />

this solution <strong>in</strong>to 3D space. This process is done by attribut<strong>in</strong>g each po<strong>in</strong>t<br />

of the (12) with appropriate altitude. This is done <strong>in</strong> the follow<strong>in</strong>g way: For each

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