capture.js

var childProcess = require('child_process');

//take a snapshot using the webcam with ffmpeg
childProcess.exec('/home/root/bin/ffmpeg/ffmpeg -loglevel panic -y -s 320x240 -f video4linux2 -i /dev/video0 -vframes 1 ./capture.jpeg');
/***********************************************************
ffmpeg flags:
    * -loglevel - set the logging level used by the library
    * -y - overwrite output files without asking
    * -s - set frame size WxH
    * -f - force format
    * -i - input filename
    * -vframes - set the number of video frames to output
    * ./capture.jpeg - output name
***********************************************************/

var gcloud = require('gcloud')({
  projectId: 'YOUR_PROJECT_ID',
  keyFilename: 'YOUR_KEY_LOCATION'
});

var vision = gcloud.vision();

vision.detectLabels('./capture.jpeg', { verbose : true }, function(err, labels){
  if(err){
    console.log(err);
  }else{
    console.log(labels);
  }
});