HandTrackingUtilities.java

/**
 * Copyright (C) 2013 Colorado School of Mines
 *
 * This file is part of the Interface Software Development Kit (SDK).
 *
 * The InterfaceSDK is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The InterfaceSDK is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the InterfaceSDK.  If not, see <http://www.gnu.org/licenses/>.
 */
package edu.mines.acmX.exhibit.stdlib.input_processing.tracking;

import org.OpenNI.DepthGenerator;
import org.OpenNI.Point3D;
import org.OpenNI.StatusException;

import edu.mines.acmX.exhibit.stdlib.graphics.Coordinate3D;

public class HandTrackingUtilities {
	
	/**
	 * Converts a Point3D provided by OpenNI to use a generic Coordinate3D.O
	 * @param gen OpenNI DepthGenerator
	 * @param point OpenNI Point3D for the given hand
	 * @return a POJO Coordinate3D
	 * 
	 * @see {@link Coordinate3D}
	 */
	public static Coordinate3D convertOpenNIPoint(DepthGenerator gen, Point3D point) {
		Point3D convertedPoint = null;
		Coordinate3D ret = null;
		try {
			convertedPoint = gen.convertRealWorldToProjective(point);
			ret = new Coordinate3D(convertedPoint.getX(),
					convertedPoint.getY(),
					convertedPoint.getZ());
		} catch (StatusException e) {
			e.printStackTrace();
		}
		
		return ret;
	}
	
	/**
	 * Scales a given hand coordinate to fill the user frame, and zooms the sensitive area of
	 * the hand device.
	 * 
	 * @param handX The unmodified hand position (float)
	 * @param depthWidth The width of the frame used by the depth sensor (int)
	 * @param frameWidth The width of the window to be converted to (int)
	 * @param marginFraction The fraction of the screen to trim from the edges (float)
	 * @return The scaled hand position (int)
	 */
	public static int getScaledHandX(float handX, int depthWidth, int frameWidth, float marginFraction) {
		//if no scaling is desired, 0 or any negative number will calculate a flat ratio of screen sizes
		if (marginFraction <= 0) return (int) (handX * (float) frameWidth/depthWidth);
		// if the margin is greater than 1/2 (would give negative remaining size), return flat ratio
		if (marginFraction > 0.5) return (int) (handX * (float) frameWidth/depthWidth);
		//get margin size (fraction of total screen size)
		float marginX = depthWidth * marginFraction;
		//find remainder of depth image to zoom into
		float scaledDepthWidth = depthWidth - 2 * marginX;
		//translate coordinate to new zoomed frame, and then perform screen size ratio
		int newX = (int) ((handX - marginX) * frameWidth/scaledDepthWidth);
		//if the calculated value is outside of the bounds of [0, frameWidth], return closest valid value
		if (newX < 0) return 0;
		if (newX > frameWidth) return frameWidth;
		return newX;
		
	}
	
	/**
	 * Scales a given hand coordinate to fill the user frame, and zooms the sensitive area of
	 * the hand device.
	 * 
	 * @param handY The unmodified hand position (float)
	 * @param depthHeight The height of the frame used by the depth sensor (int)
	 * @param frameHeight The height of the window to be converted to (int)
	 * @param marginFraction The fraction of the screen to trim from the edges (float)
	 * @return The scaled hand position (int)
	 */
	public static int getScaledHandY(float handY, int depthHeight, int frameHeight, float marginFraction) {
		//if no scaling is desired, 0 or any negative number will calculate a flat ratio of screen sizes
		if (marginFraction <= 0) return (int) (handY * (float) frameHeight/depthHeight);
		// if the margin is greater than 1/2 (would give negative remaining size), return flat ratio
		if (marginFraction > 0.5) return (int) (handY * (float) frameHeight/depthHeight);
		//get margin size (fraction of total screen size)
		float marginY = depthHeight * marginFraction;
		//find remainder of depth image to zoom into
		float scaledDepthHeight = depthHeight - 2 * marginY;
		//translate coordinate to new zoomed frame, and then perform screen size ratio
		int newY = (int) ((handY - marginY) * frameHeight/scaledDepthHeight);
		//if the calculated value is outside of the bounds of [0, frameHeight], return closest valid value
		if (newY < 0) return 0;
		if (newY > frameHeight) return frameHeight;
		return newY;
	}
}