Calculates a rough distance metric about what distance the face has to the device. - Android java.lang

Android examples for java.lang:Math

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Description

Calculates a rough distance metric about what distance the face has to the device.

Demo Code


//package com.java2s;
import android.graphics.Point;

public class Main {
    /**/*from w w w  .j a  v a  2s . c o  m*/
     * the optical angle of the device's camera, measured on the longer side of
     * the picture. in rad.
     */
    public static float CAMERA_ANGLE_LONG_SIDE_DEFAULT = (float) Math.PI / 180f * 62f;
    /** the average detected face height in cm. */
    public static float AVERAGE_DETECTED_FACE_HEIGHT = 16f;

    /**
     * Calculates a rough distance metric about what distance the face has to
     * the device. <b>This is neither an exact, nor a proportional
     * calculation!</b>
     * 
     * @param _faceDimension
     * @param _cameraPictureSize
     * @param _subsamplingFactor
     * @param _cameraAngleLongSide
     * @return
     */
    public static float calculateDistanceMetric(Point _faceDimension,
            Point _cameraPictureSize, float _subsamplingFactor,
            float _cameraAngleLongSide, float _agerageDetectedFaceHeight) {
        // the longer side of the camera picture is our reference length
        int camLength = Math
                .max(_cameraPictureSize.x, _cameraPictureSize.y);
        // use the height of the face for reference length
        int faceLength = (int) (_faceDimension.x * _subsamplingFactor);
        // return (float) faceLength / (float) camLength;
        return (float) (_agerageDetectedFaceHeight / Math
                .atan(_cameraAngleLongSide / camLength * faceLength));
    }

    /**
     * See {@link #calculateDistanceMetric(Point, Point, float, float, float)}
     * with {@link #CAMERA_ANGLE_LONG_SIDE_DEFAULT} and
     * {@link #CAMERA_ANGLE_LONG_SIDE_DEFAULT}.
     * 
     * @param _faceDimension
     * @param _cameraPictureSize
     * @param _subsamplingFactor
     * @return
     */
    public static float calculateDistanceMetric(Point _faceDimension,
            Point _cameraPictureSize, float _subsamplingFactor) {
        return calculateDistanceMetric(_faceDimension, _cameraPictureSize,
                _subsamplingFactor, CAMERA_ANGLE_LONG_SIDE_DEFAULT,
                AVERAGE_DETECTED_FACE_HEIGHT);
    }
}

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