Unity + Leap: Explicit instruction and hand gestures

I have been experimenting a bit with the LEAP and looking at getting objects into the user’s hand. In one of my experiments*, the user holds their hand out flat and a fairy appears. This experiment used explicit instruction written on menus to tell the user what to do.




Explicit instruction worked in that my test users did what I wanted them to - nod and hold their hand out flat. The downside, of course, is that it required them to read instructions which isn’t very immersive or fun. In future experiments, I want to look at implicit instruction, such as having non-player characters perform actions first.

* This demo is now available from the  Leap Motion Gallery.

Notes on getting an object to appear on a user’s hand

Some quick notes on getting the fairy to appear on the user’s hand:

You can find all of the hand models in a scene using:

HandModel[] userHands = handcontroller.GetAllPhysicsHands();

To know if the hand is palm up, you can get the normal vector projecting from the hand relative to the controller, using:

userHands[0].GetPalmNormal()

To know if the hand is open or closed, you can look at the hand’s grab strength. The strength is zero for an open hand, and blends to 1.0 when a grabbing hand pose is recognized.

userHands[0].GetLeapHand().GrabStrength

To know where to place the object, you can get the palm position (relative to the controller), using:

userHands[0].GetPalmPosition()

Unity + Leap: Hand Selection UI Prototype

Immersion is definitely affected by how closely your avatar's hand looks like your own.  In the demo I am working on I want the user to be able to select the hands they have in the game before entering the game.  A prototype in-game UI for hand selection is seen in the video below.

To create this UI, I created a world space canvas and added buttons for each of the available hands. To each button, I added a box collider as a child object. A script attached to the box collider detects when a hand has collided with it.  To detect a hand, I used the Leap libraries and then checked to see if the collision object is a Leap HandModel.

In this prototype UI, I am using large buttons for two reasons. First, reading small text in the Rift can be difficult, and second, while using the Leap allows me to see my hands, in my experience, it does not track finger motion well enough for detailed interactions to be effective. In several of the tests I ran, the user's hand was generally in the right place but the fingers more often than not were at different angles than the user's actual hand. The effect was that my users seemed to have the fine motor skills of a toddler - they could reach out and touch everything but they didn't have a lot of control. On the positive side, when the user has hands in the game, it appears to be very natural for users to try to touch items with their hands. Even when users don't have visible hands in the scene, you'll often see them reaching out to try to touch things. While I have the start button say "Touch to Start," once users know to use their hand to affect the scene they get it right away and don't need prompting or other instruction.

Leap Motion has just released a "Best Practices Guide" and I'll be looking at incorporating many of the ideas documented there in future prototypes.