Processing Open CV Face Tracking

Question

Hi I started with the code vom Sparkfun below to do some Face Tracking and get this error:

the type OpenCV is ambiguous

I tried other examples from the OpenCV for Processing library. And they work without a problem (Also the Face Tracking Example) The original code from Sparkfun was written for a different OpenCV (Version 1 I believe). But I could not make it work, because there is no import library at the top of the code. Since I have OpenCV for Processing installed I imported that:

import gab.opencv.*;

and from then on I get this error. I don't see why it does not work and I don't understand why it was supposed to work (since it does not import OpenCV in the orginal code).

Any help would be great.

Thanks.

/**********************************************************************************************
* Pan/Tilt Face Tracking Sketch
* Written by Ryan Owens for SparkFun Electronics
* Uses the OpenCV real-time computer vision  framework from Intel
* Based on the OpenCV Processing Examples from ubaa.net
* This example is released under the Beerware License.
* (Use the code however you'd like, but mention us and by me a beer if we ever meet!)
*
* The Pan/Tilt Face Tracking Sketch interfaces with an Arduino Main board to control
* two servos, pan and tilt, which are connected to a webcam. The OpenCV library
* looks for a face in the image from the webcam. If a face is detected the sketch
* uses the coordinates of the face to manipulate the pan and tilt servos to move the webcam
* in order to keep the face in the center of the frame.
*
* Setup-
* A webcam must be connected to the computer.
* An Arduino must be connected to the computer. Note the port which the Arduino is connected on.
* The Arduino must be loaded with the SerialServoControl Sketch.
* Two servos mounted on a pan/tilt backet must be connected to the Arduino pins 2 and 3.
* The Arduino must be powered by a 9V external power supply.
* 
* Read this tutorial for more information:
**********************************************************************************************/
import gab.opencv.*;
import hypermedia.video.*;  //Include the video library to capture images from the webcam
import java.awt.Rectangle;  //A rectangle class which keeps track of the face coordinates.
import processing.serial.*; //The serial library is needed to communicate with the Arduino.


OpenCV opencv; //Create an instance of the OpenCV library.

//Screen Size Parameters
int width = 320;
int height = 240;

// contrast/brightness values
int contrast_value    = 0;
int brightness_value  = 0;

Serial port; // The serial port

//Variables for keeping track of the current servo positions.
char servoTiltPosition = 90;
char servoPanPosition = 90;
//The pan/tilt servo ids for the Arduino serial command interface.
char tiltChannel = 0;
char panChannel = 1;

//These variables hold the x and y location for the middle of the detected face.
int midFaceY=0;
int midFaceX=0;

//The variables correspond to the middle of the screen, and will be compared to the midFace values
int midScreenY = (height/2);
int midScreenX = (width/2);
int midScreenWindow = 10;  //This is the acceptable 'error' for the center of the screen. 

//The degree of change that will be applied to the servo each time we update the position.
int stepSize=1;

void setup() {
  //Create a window for the sketch.
  size( width, height );

  opencv = new OpenCV( this );
  opencv.capture( width, height );                   // open video stream
  opencv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT );  // load detection description, here-> front face detection : "haarcascade_frontalface_alt.xml"

  println(Serial.list()); // List COM-ports (Use this to figure out which port the Arduino is connected to)

  //select first com-port from the list (change the number in the [] if your sketch fails to connect to the Arduino)
  port = new Serial(this, Serial.list()[0], 57600);   //Baud rate is set to 57600 to match the Arduino baud rate.

  // print usage
  println( "Drag mouse on X-axis inside this sketch window to change contrast" );
  println( "Drag mouse on Y-axis inside this sketch window to change brightness" );

  //Send the initial pan/tilt angles to the Arduino to set the device up to look straight forward.
  port.write(tiltChannel);    //Send the Tilt Servo ID
  port.write(servoTiltPosition);  //Send the Tilt Position (currently 90 degrees)
  port.write(panChannel);         //Send the Pan Servo ID
  port.write(servoPanPosition);   //Send the Pan Position (currently 90 degrees)
}


public void stop() {
  opencv.stop();
  super.stop();
}



void draw() {
  // grab a new frame
  // and convert to gray
  opencv.read();
  opencv.convert( GRAY );
  opencv.contrast( contrast_value );
  opencv.brightness( brightness_value );

  // proceed detection
  Rectangle[] faces = opencv.detect( 1.2, 2, OpenCV.HAAR_DO_CANNY_PRUNING, 40, 40 );

  // display the image
  image( opencv.image(), 0, 0 );

  // draw face area(s)
  noFill();
  stroke(255,0,0);
  for( int i=0; i<faces.length; i++ ) {
    rect( faces[i].x, faces[i].y, faces[i].width, faces[i].height );
  }

  //Find out if any faces were detected.
  if(faces.length > 0){
    //If a face was found, find the midpoint of the first face in the frame.
    //NOTE: The .x and .y of the face rectangle corresponds to the upper left corner of the rectangle,
    //      so we manipulate these values to find the midpoint of the rectangle.
    midFaceY = faces[0].y + (faces[0].height/2);
    midFaceX = faces[0].x + (faces[0].width/2);

    //Find out if the Y component of the face is below the middle of the screen.
    if(midFaceY < (midScreenY - midScreenWindow)){
      if(servoTiltPosition >= 5)servoTiltPosition -= stepSize; //If it is below the middle of the screen, update the tilt position variable to lower the tilt servo.
    }
    //Find out if the Y component of the face is above the middle of the screen.
    else if(midFaceY > (midScreenY + midScreenWindow)){
      if(servoTiltPosition <= 175)servoTiltPosition +=stepSize; //Update the tilt position variable to raise the tilt servo.
    }
    //Find out if the X component of the face is to the left of the middle of the screen.
    if(midFaceX < (midScreenX - midScreenWindow)){
      if(servoPanPosition >= 5)servoPanPosition -= stepSize; //Update the pan position variable to move the servo to the left.
    }
    //Find out if the X component of the face is to the right of the middle of the screen.
    else if(midFaceX > (midScreenX + midScreenWindow)){
      if(servoPanPosition <= 175)servoPanPosition +=stepSize; //Update the pan position variable to move the servo to the right.
    }

  }
  //Update the servo positions by sending the serial command to the Arduino.
  port.write(tiltChannel);      //Send the tilt servo ID
  port.write(servoTiltPosition); //Send the updated tilt position.
  port.write(panChannel);        //Send the Pan servo ID
  port.write(servoPanPosition);  //Send the updated pan position.
  delay(1);
}



/**
 * Changes contrast/brigthness values
 */
void mouseDragged() {
  contrast_value   = (int) map( mouseX, 0, width, -128, 128 );
  brightness_value = (int) map( mouseY, 0, width, -128, 128 );
}

Answer 1

You're using two separate Processing wrappers for OpenCV(gab.* and hypermedia.*), both having an OpenCV class of they're own. Use one or the other but not both in the same project. Java can't tell which one you want to use(hence the ambiguous OpenCV type error)

You seem to be using the hypermedia classes anyway, so remove the gab.* import for now as a quick fix.

The gab.* library though is better (more up to date) than the hypermedia one, so you might want to update you OpenCV calls to use that one in the future.