Detecting object's distance away from camera in augmented reality (ARKit, etc.)?

Question

Is it possible in ARKit or other similar library to detect distance away from an object within any sort of accuracy or precision?

What are the limits or tolerance to the accuracy or precision of that distance value if the size and range is in two different real-world scene categories:

Vertical height is 1/8" to 6" and is 6" to 24" away from the camera
Vertical height is 5' to 20' and is 5' to 20' away from the camera

For example, for 1 above: can I hold a coffee cup or a car key at arms length away and detect how far away it is within some precision? For 2 above: can I stand in front of a tree and detect how far away the tree is?

If distance away (Z dimension) is possible within a high degree of precision, does that mean its vertical height (Y dimension) can be measured or calculated within some proportional precision?

To test this, suggestions on the core code elements?

Jordan Jordan · Accepted Answer · 2018-10-09T06:50:09

This is certainly possible with ARKit.

As ARKit runs it finds features in the environment. These are points which it can recognise repeatedly, and uses to determine the 'pose' of the camera.

These features points come with an [x, y, z] position in real world space (relative to the camera). If you tap on one the screen ARKit can give you the 3D pose of the closest feature point that you tapped on.

To get the position of an object you would have to:

Use a gesture recogniser to detect a tap on the screen
Find the feature point that was tapped on
Get the position of this feature point

The following functions will be useful for you.

In viewDidLoad

let gestureRecognizer = UITapGestureRecognizer(target: self, action: #selector( self.handleSingleTap ))
self.sceneView.addGestureRecognizer(gestureRecognizer)

with:

@objc func handleSingleTap ( recogniser: UIGestureRecognizer) {
    let touchPosition = recogniser.location(in: self.sceneView)

    let featureHitTestResult = self.sceneView.hitTest(touchPosition, types: .featurePoint)

    if !featureHitTestResult.isEmpty {
        hitFeature = featureHitTestResult.first
    }
}

You can then get the position from the hitFeature and use it to determine the distance from the current camera position.

Detecting object's distance away from camera in augmented reality (ARKit, etc.)?

1 Answers