Department of Depth & Color

Calibrating Custom Structure Sensor Attachments

Select your sensor.

Structure Sensor (Mark II)
Original Structure Sensor (ST01)

Using a custom iPhone/iPod case or iPad bracket? Great! Let's get the numbers right.

In order to calibrate your sensor, you will need to specify the coordinates of the translation from the color to the depth camera, shown below. These values are critical to computing an accurate depth-color registration and need to be precisely measured.

The X horizontal component is measured from the camera centers:

Similarly, the Y vertical component is measured from the camera centers:

For the depth displacement you need to take into account the distance between the camera surfaces and their entrance pupils. The Structure Sensor's depth camera is located millimeters below its glass surface. The iOS color camera entrance pupil can be located at different depths from the surface, depending on the actual device being used. One millimeter from the device surface can usually be considered a reasonable estimate.

Designing your custom attachment? Here's what you need to know!

  • Structure Sensor Dimensions

    • - The location of the depth viewpoint in the Structure Sensor is shown below. Dimension are in millimeters.

    • - The Structure Sensor mounting profile is as follows:

  • Custom Attachment Design Pitfalls:

    • - Orient the Structure Sensor horizontally with the camera, and pointing in the same direction:

      (a) Bad Orientation
      (b) Good Orientation
    • - Minimize the Structure Sensor vertical displacement:

      (a) Bad Alignment
      (b) Good Alignment
    • - Don’t block the iOS device’s camera with the Structure Sensor.

      (a) Bad Position
      (b) Good Position
    • - Last, try and minimize the sensor Z-displacement by keeping its back cover flush with the back of the iOS device.