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<td class="title">Demonstrations</td>
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<h1>mmdairport
<br>
<span class="subtitle">Detecting runways in satellite airport imagery.
</span>
</h1>
<div class="descr">
<H2>Description</H2>
<div class="H2">
<p>
In this example, a satellite image of an airport is processed. The aim is to detect the runways which are characterized by thin, long and straight features. An open top-hat is first used to enhance the runways. A rough thresholding followed by a thinning operator gives most of the thin structures of the image. They can filtered by selecting only closed features with sufficient length. This result is used as a marker to reconstruct the original gray-scale image, giving as output a gray-scale enhanced airport runways, which can be finally thresholded.
</p>
</div>
</div>
<div class="script">
<H2>Demo Script</H2>
<div class="H2">
<div class="slide">
<H3>Reading</H3>
<div class="H3">
<p>
<p>
The satellite image of the airport is read.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> f = mmreadgray('galeao.jpg')</pre>
<pre class="computer"></pre>
<pre class="user">>>> mmshow(f)</pre>
<pre class="computer"></pre>
</div>
<table class="images">
<tbody align="center">
<tr class="image" valign="bottom">
<td><img width="320" src="../images/img_mmdairport_001.jpg"></td>
<td class="spare"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_001.jpg">f</a></td>
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</p>
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<div class="slide">
<H3>First, enhance the runways by an open top-hat.</H3>
<div class="H3">
<p>
<p>
The disk of radius 5 (diameter 11) is chosen to detect features smaller than this size. For visualization, the top-hat image is brightened by 150 gray-levels.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> th=mmopenth(f,mmsedisk(5))</pre>
<pre class="computer"></pre>
<pre class="user">>>> mmshow(mmaddm(th, 150))</pre>
<pre class="computer">Warning: Converting input image from int32 to uint8.</pre>
</div>
<table class="images">
<tbody align="center">
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<td><img width="320" src="../images/img_mmdairport_002.jpg"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_002.jpg">mmaddm(th, 150)</a></td>
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</p>
</div>
</div>
<div class="slide">
<H3>Followed by a thresholding.</H3>
<div class="H3">
<p>
<p>
A thresholding is applied to detect the features enhanced by the top-hat. This is a standard top-hat sequence.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> bin=mmthreshad(th,30)</pre>
<pre class="computer">Warning: Converting input image from int32 to uint8.</pre>
<pre class="user">>>> mmshow(f,bin)</pre>
<pre class="computer"></pre>
</div>
<table class="images">
<tbody align="center">
<tr class="image" valign="bottom">
<td><img width="320" src="../images/img_mmdairport_003.jpg"></td>
<td class="spare"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_003.jpg">f,bin</a></td>
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</p>
</div>
</div>
<div class="slide">
<H3>Thinning, pruning and area open.</H3>
<div class="H3">
<p>
<p>
The thinning (red) and pruning (green) detect closed structures which characterized the runways structure. The area open (blue) selects only very long features, with more than 1000 pixels.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> m1=mmthin(bin)</pre>
<pre class="computer"></pre>
<pre class="user">>>> m2=mmthin(m1,mmendpoints())</pre>
<pre class="computer"></pre>
<pre class="user">>>> m=mmareaopen(m2,1000,mmsebox())</pre>
<pre class="computer"></pre>
<pre class="user">>>> mmshow(f,m1,m2,m)</pre>
<pre class="computer"></pre>
</div>
<table class="images">
<tbody align="center">
<tr class="image" valign="bottom">
<td><img width="320" src="../images/img_mmdairport_004.jpg"></td>
<td class="spare"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_004.jpg">f,m1,m2,m</a></td>
<td class="spare"></td>
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</p>
</div>
</div>
<div class="slide">
<H3>Reconstruction.</H3>
<div class="H3">
<p>
<p>
The previous result is a sample of the runway pixels. It is used as a marker for gray-scale morphological reconstruction. The runways are enhanced in the reconstructed image.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> g=mminfrec(mmgray(m), th)</pre>
<pre class="computer"></pre>
<pre class="user">>>> mmshow(g)</pre>
<pre class="computer"></pre>
</div>
<table class="images">
<tbody align="center">
<tr class="image" valign="bottom">
<td><img width="320" src="../images/img_mmdairport_005.jpg"></td>
<td class="spare"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_005.jpg">g</a></td>
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</p>
</div>
</div>
<div class="slide">
<H3>Final thresholding.</H3>
<div class="H3">
<p>
<p>
A thresholding is applied to the reconstructed image, detecting the airport runways.
</p>
<div class="example">
<div class="listing">
<pre class="user">>>> final=mmthreshad(g, 20)</pre>
<pre class="computer">Warning: Converting input image from int32 to uint8.</pre>
<pre class="user">>>> mmshow(f, final)</pre>
<pre class="computer"></pre>
</div>
<table class="images">
<tbody align="center">
<tr class="image" valign="bottom">
<td><img width="320" src="../images/img_mmdairport_006.jpg"></td>
<td class="spare"></td>
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<tr class="title" valign="baseline">
<td><a href="../images/img_mmdairport_006.jpg">f, final</a></td>
<td class="spare"></td>
</tr>
</tbody>
</table>
</div>
</p>
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<td class="copyright">Copyright (c) 2003, Roberto A. Lotufo, UNICAMP-University of Campinas; Rubens C. Machado, CenPRA-Renato Archer Research Center.</td>
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distrib
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Mandriva
>
2010.0
>
i586
>
media
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contrib-release
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by-pkgid
>
4a71d9984febeb5a206904a5a379841a
>
files
>
609
