Getting Started with Calibration

What is Calibration?

Believe it or not, most hardware doesn't work perfectly the exact moment it's assembled. Assembling headsets by hand leads to small variances in each headset that need to be compensated for in software. In order to get the best experience with your ProjectNorthstar headset, you'll need to follow a few steps in order to compensate for these variances.

Optical Calibration

The first type of calibration you'll need to do is classified as Optical Calibration. This type of calibration uses stereo cameras to calculate the image distortion caused by the parabolic reflectors in the ProjectNorthstar headset. There are two versions of Optical Calibrations you can do based on what hardware you have access to. Both versions of optical calibration currently require a Calibration Stand to be 3D printed. The calibration methods distort the normal image displayed on the screens to make it appear correctly on the headset. Unity, unreal and other engines/compositors need to be able to take the information generated by the calibration method, and plug that into a rendering method in order to properly compute the image. Please see the table below for which methods are currently supported on specific platforms.

3D Optical Calibration

3D Optical Calibration calculates the exact position of your headset's screens and Optical Combiners, and uses raytracing (not the RTX kind, don't worry) to calculate the distortion for the headset. This allows it to be adjusted for multiple Interpupillary distances and eye reliefs. This method requires using two Stereo cameras and an external monitor (in addition to your main screen) to work. This makes it more expensive/complicated to do compared to 2D Optical Calibration. We currently recommend this method for maker spaces or groups that have to calibrate multiple headsets. This is the method used for preassembled and calibrated headsets from smart-prototyping and CombineReality.

2D Optical Calibration

Unlike the 3D Optical Calibration, 2D Optical Calibration only calculates the 2D distortion generated by the headset's Optical configuration. This method is much simpler to setup. It only requires one stereo camera, which you likely already have for your headset! You can use the intel t261, t265 currently, but if you have another stereo camera reach out on the discord and we will see what we can do to support it.

Calibrating Hand Position

Hand position is dependent on the position of the leap motion sensor, make sure your Leap motion sensor has the bottom metal bezel hidden behind the 3d printed housing. You can use this application to set up your hand position: https://github.com/fmaurer/NorthStarToolbox

3D and 2D Calibration Feature Comparison

Calibration Stand Assembly

Both the 2D and 3D versions of the calibration setup share the same 3D printable stand. You can find the assembly instructions below. (Note that they show the instructions for the original, 3D dual camera, stand.)

3D Optical Calibration

2D Optical Calibration