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OpenCV + Asus Xtion sensor

asked 2014-05-17 00:44:39 -0500

chaanakya gravatar image

Dear all,

I am having trouble getting the Asus Xtion sensor to work with the OpenCV framework. I know (or at least I believe) the problem is not my laptop as I have an example program working with PCL (the Point Cloud Library). I am using Debian Sid with a custom compiled OpenCV (to ensure support for OpenNI and the Xtion sensor). The following code is what should work, but is not:

#include "opencv2/opencv.hpp"
using namespace cv;
using namespace std;

int main(int argc, char* argv[])
{
  VideoCapture capture( CAP_OPENNI_ASUS );
  if (!capture.isOpened())
  {
  exit(1);
  }
  for(;;)
  {
  Mat depthMap;
  capture >> depthMap;

  if( waitKey( 30 ) >= 0 )
    break;
  }
}

This code compiles just fine. When I run it, however, with the Xtion sensor plugged in, it gives me the following output:

CvCapture_OpenNI::CvCapture_OpenNI : Failed to run xml script: Bad Parameter sent to the device!

What exactly is going on and how do I fix it? I have tried searching on Google and haven't found anything useful except for other people with the same problem and no responses.

Thank you very much in advance.

Sincerely,

Chaanakya

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Comments

Does SamplesConfig.xml have anything at all to do with this not working? It seems that it should read /etc/openni/SamplesConfig.xml. However, I don't think it's doing that, since a) PCL worked (and works) just fine and b) nothing I do is actually changing the behavior of OpenCV.

chaanakya gravatar imagechaanakya ( 2014-05-18 12:11:25 -0500 )edit

Hi,

I don't know the answer, but maybe I can give you a hint. (I never used OpenNI 1.5, it's quite outdated; I prefer to use the newer OpenNI2.2 and transform the captured data to OpenCV Mat).

To get back to your question: the OpenNI capture is implemented in the modules/highgui/src/cap_openni.cpp file. There you can find a global variable called XMLConfig, right at the beginning. The CvCapture_OpenNI constructor tries to run this script, but it seems that it fails; there is a parameter in the XML text that your device doesn't understand.

workarounds: a) use OpenNI separately and transform the image to Mat; b) try to get a valid XML config file for your device; c) set the device in verbose mode (check the settings in OpenNI), maybe it gives you more hint about that bad parameter.

kbarni gravatar imagekbarni ( 2014-05-19 08:55:49 -0500 )edit

Thanks kbarni - I did change that variable and the result does work. How exactly do you do a) though? I'd like to do that if possible. Thanks!

chaanakya gravatar imagechaanakya ( 2014-05-26 23:02:10 -0500 )edit

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answered 2014-05-27 03:38:28 -0500

kbarni gravatar image

updated 2014-05-27 03:39:09 -0500

Here is how to use OpenNI2.2 with OpenCV. The code is untested, but it should work.

To be shorter, I omitted the verifications from the code, but you should really check the result of every operation like this:

openni::Status rc;
rc=anyOpenNIOpreation();
if(rc!=openni::STATUS_OK){
    printf("Error! %d\n\n",rc);
    openni::OpenNI::shutdown();
    exit(0);
}

First you initialize OpenNI and the cameras:

openni::Device device;
openni::VideoStream depth, color,ir;

openni::OpenNI::initialize();
device.open(openni::ANY_DEVICE);

ir.create(device,openni::SENSOR_IR);
depth.create(device, openni::SENSOR_DEPTH);
color.create(device, openni::SENSOR_COLOR);

In this example I'll use the depth stream for capture. First we need the resolution:

openni::VideoMode vm=depth.getVideoMode();
int cols,rows;
cols=vm.getResolutionX();
rows=vm.getResolutionY();

Then, we capture the image:

openni::VideoFrameRef frame;
depth.start();
stream->readFrame(&frame);   
depth.stop();

Finally, you get the frame data and create a Mat variable using that data:

openni::DepthPixel* dData = (openni::DepthPixel*)frame.getData();
cv::Mat depthImage(rows, cols, CV_16UC1, dData);

For the color frame you'll have to use openni::RGB888Pixel as pixel type and CV_8UC3 as matrix type.

Hope this helps!

openni::OpenNI::shutdown();
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Asked: 2014-05-17 00:44:39 -0500

Seen: 5,911 times

Last updated: May 27 '14