The problem I am having is trying to figure out the byte/value/pixel range size that is being sent to the arduino.  Using the following as imports : SimpleOpenNI and processing.serial. Code is here:

 //if user is successfully calibrated
    if ( kinect.isTrackingSkeleton(userId)) {
       drawSkeleton(userId); //draw the skeleton on the depth image
     
       PVector torso = new PVector();  //make a vector to store torso
       kinect.getJointPositionSkeleton(userId, SimpleOpenNI.SKEL_TORSO, torso);  //put the position of torso into vector
       port.write(int(torso.z));  //z-coordinate corresponds to how far it is from kinect, convert to int and send data through serial port
     }

I found the user's torso.z from depth image and sent this to arduino.
The corresponding arduino code is here :
void loop(){
 
  if(Serial.available() > 0)
  {
    serialData = Serial.read();
    Serial.println(serialData);
  }
}

From here I'd like to set up a threshold for my motors to maintain.  Having them both spin forward/backward to maintain 3 feet from the kinect except I don't know the depth integer range that I can manipulate.  Kinect depth range can be from 0 to 80k pixels.