Android (Glass) Unable to Detect Faces in onFaceDetection

Question

I have a small app just to test out camera preview and facial recognition. The preview surface displays and I can see the onFaceDetection callback getting called. If I put a Log call in onFaceDetection I see it called repeatedly, but with an empty Faces[] array.

Note: The "Log" call below is not the one that is called, the Log call in my example below is never called. But I can add another Log call outside of the for statement and that will be called.

Here's my code:

package com.example.glassgoggles;

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Face;
import android.hardware.Camera.FaceDetectionListener;
import android.hardware.Camera.Parameters;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraPreviewView extends SurfaceView implements SurfaceHolder.Callback, FaceDetectionListener {

    private SurfaceHolder surfaceHolder = null;
    private Camera camera = null;

    @SuppressWarnings("deprecation")
    public CameraPreviewView(Context context) {
        super(context);

        surfaceHolder = this.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

        camera = Camera.open();
        this.setCameraParameters();
        try 
        {
            camera.setPreviewDisplay(holder);
        } 
        catch (Exception e) 
        {
            this.releaseCamera();
        }

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        if (camera != null)
        {
            camera.setFaceDetectionListener(this);
            camera.startPreview();
            this.startFaceDetectionIfSupported();
        }

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        this.releaseCamera();       
    }

    public void releaseCamera() 
    {
        if (camera != null) 
        {
            camera.release();
            camera = null;
        }
    }

    public void setCameraParameters()
    {
        if (camera != null)
        {
            Parameters parameters = camera.getParameters();
            parameters.setPreviewFpsRange(30000, 30000);
            camera.setParameters(parameters);   
        }
    }

    public void startFaceDetectionIfSupported() {
        if (camera != null) {
            Parameters parameters = camera.getParameters();
            if (parameters.getMaxNumDetectedFaces() > 0) {
                Log.d("Face Detection", "Starting...");
                camera.startFaceDetection();
            } else {
                Log.d("Face Detection", "No faces allowed...");
            }
        }
    }

    @Override
    public void onFaceDetection(Face[] faces, Camera camera) {
        for(int i = 0; i < faces.length; i++) {
            Log.d("Face Check", "Found a face...");
        }
    }

}

See: https://code.google.com/p/google-glass-api/issues/detail?id=282 — Morrison Chang, May 19 '14 at 05:23
The link above gives the impression that there is no solution - Glass does not capture any faces while using the preview. Is this your conclusion @DavidKullmann? If so, have you played with FaceDetector and Glass? — Clocker, May 19 '15 at 19:07

score 1 · Answer 1 · answered May 20 '14 at 09:51

Face detection is not facial recognition. It's just a way to identify if there are faces in the camera preview, it can be used for a feature like when a phone camera preview draws a box around faces and maybe focuses on the faces. But Glass has a fixed focus camera, so face detection isn't really applicable. On top of this ...

Facial recognition is explicitly disallowed in the Google Glass Policies for Glassware.

Section C.1.e says:

Don't use the camera or microphone to cross-reference and immediately present personal information identifying anyone other than the user, including use cases such as facial recognition and voice print. Glassware that do this will not be approved at this time.

Reference:

https://developers.google.com/glass/policies

I hope that adds some clarity to your question. If your usage of "facial recognition" was a typo and you meant to say "face detection" you should edit your question.

Android (Glass) Unable to Detect Faces in onFaceDetection

1 Answers1