Peter Huewe at 20:45, 27 October 2011

2011-10-27T20:45:42Z

Simonea: Covered work done getting opencv functioning on BeagleBoard

2010-05-12T17:09:56Z

Covered work done getting opencv functioning on BeagleBoard

New page

==Introduction==

There are currently a dozen examples as well as instructions on using opencv, including incomplete references on this wiki: [[BeagleBoardOpenCV|Using OpenCV computer vision library with BeagleBoard]] and 'Running OpenCV on the BB' on [http://groups.google.com/group/beagleboard Google Groups]. As an 'unstable' package for the BeagleBoard however, the OpenCV packages are currently beyond the last update. For the sake of simplicity, this page will detail natively compiling opencv applications on the BeagleBoard.

==Installing OpenCV==
After running 'opkg update', you should have access to the most current opencv packages:
*opencv - 2.1.0
*opencv-apps - 2.1.0
*opencv-dbg - 2.1.0
*opencv-dev - 2.1.0
*opencv-doc - 2.1.0
*opencv-samples - 2.1.0
*opencv-samples-dbg - 2.1.0
*opencv-samples-dev - 2.1.0
*python-opencv
For the purposes of cross-compiling on the BeagleBoard, you will need the opencv header in opencv-dev and the libraries from opencv-apps. The 'opencv' package is currently a dummy that the others all list as a dependency.

At the time of this writing, the libraries are not properly installed from opencv-apps. It is possible to check for correct install by looking for the file 'libhighgui.so' in /usr/lib. Installing opencv-apps adds libhighgui.so.2.1 and libhighgui.so.2.1.0, however libhighgui.so is required for the linker to find it. A quick workaround for now is to create a symbolic link between libhighgui.so and libhighgui.so.2.1 <pre> ln -s /usr/lib/libhighgui.so.2.1 /usr/lib/libhighgui.so</pre>
There are several other libraries installed that will need similar treatment as they are used.

==Other Required Packages==
We'll be using gcc to compile c programs, so make sure you have 'gcc' and 'gcc-symlinks' installed as well.

==Using a Webcam with the BeagleBoard==
So far, this has been tested with a Logitech Webcam Pro 9000, but should with with any [http://www.ideasonboard.org/uvc/ UVC Webcam]. You'll want to make sure you install the libv4l-dev package first. When you plug in the webcam, 'dmesg|tail' should show that a UVC Camera was plugged in. If not, check that your kernel module 'kernel-module-uvcvideo' isn't somehow corrupted which has happened in the past, running 'opkg update kernel-module-uvcvideo' should correct it if it is. If the webcam is recognized, then the following demo program will display a video window:

<pre>
#include <cv.h>
#include <highgui.h>
#include <cxcore.h>
#include "stdio.h"
#include "string.h"

int main(int argc, char ** argv)
{
char Vid[] = "WebCam";

IplImage * frm;
CvCapture * capture;

capture = cvCaptureFromCAM(-1); // the parameter for a cam

if( capture ) {
cvNamedWindow (Vid,1);

do {
frm = cvQueryFrame( capture );

if( frm )
cvShowImage (Vid, frm);

int k = cvWaitKey( 50 );
if (k == 27 || k == '\r') // Press ESC and Enter
break; // for out

} while( frm );

cvDestroyWindow( Vid ); // Destroy the window
cvReleaseCapture( &capture );
}
else
puts( "Cannot Open the Webcam" );
}
</pre>
To compile, make sure to include the opencv headers (-I/usr/include/opencv) and link to the highgui library (-lhighgui).

==Compile Warnings==
The following messages are generated when compiling:
<pre>
In file included from /usr/include/opencv/cxcore.h:70,
from /usr/include/opencv/cv.h:58,
from onecam.c:1
/usr/include/opencv/cxtypes.h: In function 'cvRound':
/usr/include/opencv/cxtypes.h:228: warning: incompatible implicit declaration of built-in function 'lrint'
</pre>
However, it appears they have no effect on general operation.

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ECE597 Opencv on the BeagleBoard - Revision history

Peter Huewe at 20:45, 27 October 2011

Simonea: Covered work done getting opencv functioning on BeagleBoard