js-aruco is a port to JavaScript of the ArUco library by jcmellado. This module adapts that browser library slightly to work in Node.js.

ArUco is a minimal library for Augmented Reality applications based on OpenCV.

Usage

Create an AR.Detector object:

var AR = require('js-aruco').AR;
var detector = new AR.Detector();

Call detect function:

var markers = detector.detect(imageData);

markers result will be an array of AR.Marker objects with detected markers.

AR.Marker objects have two properties:

• id: Marker id.
• corners: 2D marker corners.

imageData argument must be a valid ImageData canvas object. The pixel suite of modules may be helpful for constructing these in Node.

3D Pose Estimation

Create an POS.Posit object:

var POS = require('js-aruco').POS1;
var posit = new POS.Posit(modelSize, canvas.width);

modelSize argument must be the real marker size (millimeters).

Call pose function:

var pose = posit.pose(corners);

corners must be centered on canvas:

var corners = marker.corners;

for (var i = 0; i < corners.length; ++ i){
  var corner = corners[i];

  corner.x = corner.x - (canvas.width / 2);
  corner.y = (canvas.height / 2) - corner.y;
}

pose result will be a POS.Pose object with two estimated pose (if any):

• bestError: Error of the best estimated pose.
• bestRotation: 3x3 rotation matrix of the best estimated pose.
• bestTranslation: Translation vector of the best estimated pose.
• alternativeError: Error of the alternative estimated pose.
• alternativeRotation: 3x3 rotation matrix of the alternative estimated pose.
• alternativeTranslation: Translation vector of the alternative estimated pose.

Note: POS namespace can be taken from require('js-aruco').POS1 or .POS2.