How to average values of more frames in Processing - processing

Question

I'm working on this code to manage and save data coming from the Microsoft kinect, the data are stored in the int array int[] depthValues, what I'd like to do is to store and save an average of more frames (let's say 10), in order to get smoother data, leaving the remaining part of the code as it is.
Here's the code:
import java.io.File;
import SimpleOpenNI.*;
import java.util.*;
SimpleOpenNI kinect;
void setup()
{
size(640, 480);
kinect = new SimpleOpenNI(this);
kinect.enableDepth();
}
int precedente = millis();
void draw()
{
kinect.update();
PImage depthImage = kinect.depthImage();
image(depthImage, 0, 0);
int[] depthValues = kinect.depthMap();
StringBuilder sb = new StringBuilder();
Deque<Integer> row = new LinkedList<Integer>();
int kinectheight = 770; // kinect distance from the baselevel [mm]
int scaleFactor = 1;
int pixelsPerRow = 640;
int pixelsToSkip = 40;
int rowNum = 0;
for (int i = 0; i < depthValues.length; i++) {
if (i > 0 && i == (rowNum + 1) * pixelsPerRow) {
fillStringBuilder(sb, row);
rowNum++;
sb.append("\n");
row = new LinkedList<Integer>();
}
if (i >= (rowNum * pixelsPerRow) + pixelsToSkip) {
row.addFirst((kinectheight - depthValues[i]) * scaleFactor);
}
}
fillStringBuilder(sb, row);
String kinectDEM = sb.toString();
final String[] txt= new String[1]; //creates a string array of 2 elements
int savingtimestep = 15000; // time step in millisec between each saving
if (millis() > precedente + savingtimestep) {
txt[0] = "ncols 600\nnrows 480\nxllcorner 0\nyllcorner 0\ncellsize 91.6667\nNODATA_value 10\n" +kinectDEM;
saveStrings("kinectDEM0.tmp", txt);
precedente = millis();
// delete the old .txt file, from kinectDEM1 to kinectDEMtrash
File f = new File (sketchPath("kinectDEM1.txt"));
boolean success = f.delete();
// rename the old .txt file, from kinectDEM0 to kinectDEM1
File oldName1 = new File(sketchPath("kinectDEM0.txt"));
File newName1 = new File(sketchPath("kinectDEM1.txt"));
oldName1.renameTo(newName1);
// rename kinectDEM0.tmp file to kinectDEM0.txt
File oldName2 = new File(sketchPath("kinectDEM0.tmp"));
File newName2 = new File(sketchPath("kinectDEM0.txt"));
oldName2.renameTo(newName2);
}
}
void fillStringBuilder(StringBuilder sb, Deque<Integer> row) {
boolean emptyRow = false;
while (!emptyRow) {
Integer val = row.pollFirst();
if (val == null) {
emptyRow = true;
} else {
sb.append(val);
val = row.peekFirst();
if (val != null) {
sb.append(" ");
}
}
}
}

Answer 1

You have an int[] array variable named depthValues. You can use this value just like you can use any other value. In other words, you can create an array or ArrayList that holds multiple int[] values.
Here's how you might use an ArrayList to hold previous values:
ArrayList<int[]> previousDepthValues = new ArrayList<int[]>();
void draw(){
//add current depth map to ArrayList
previousDepthValues.add(kinect.depthMap());
//limit the ArrayList to hold 10 values
if(previousDepthValues.size() == 11){
previousDepthValues.remove(0);
}
//create an array to hold the averaged values
int[] averageDepthValues = new int[previousDepthValues.get(0).length];
//loop over the 10 previous depth values in the ArrayList
for(int[] depthValue : previousDepthValues){
//loop over the ints in each previous depth values array
for(int i = 0; i < averageDepthValues.length; i++){
//add all of the values up
averageDepthValues[i] += depthValue[i];
}
}
//divide each number to get the average
for(int i = 0; i < averageDepthValues.length; i++){
averageDepthValues[i] /= averageDepthValues.length;
}
//averageDepthValues now holds the average of the last 10 frames
}