Structure Sensor
Structure Sensor is a portable depth camera developed by Occipital that mounts to an iPad and provides structured-light depth sensing for 3D scanning, room mapping, and augmented reality applications. Launched via Kickstarter in September 2013, it was the first consumer-grade 3D scanner for mobile devices — bringing the depth sensing capability of the original Microsoft Kinect to a form factor that fit in a bag.
Hardware
The Structure Sensor uses a structured light depth sensing approach: it projects an infrared dot pattern into the scene and a co-located infrared camera reads the distortion of that pattern to compute per-pixel depth. This is the same sensing principle used in the original Kinect (based on PrimeSense technology — PrimeSense was separately acquired by Apple in 2013).4 The sensor operates at 640×480 depth resolution at 30 frames per second, with a working range of approximately 0.4 to 3.5 metres.
The device clips to the back of an iPad using a custom bracket with a Lightning connector, drawing power from and communicating over the iPad's Lightning port. The iPad's camera and processor combined with the Structure Sensor's depth data to provide RGB-D (colour plus depth) capture.1
Capabilities
Room scanning: The Structure Sensor enables real-time 3D reconstruction of indoor environments using SLAM-based integration similar to KinectFusion. Users walk through a space holding the iPad, and the sensor builds a dense mesh of walls, floors, furniture, and objects. This found immediate use in architecture, construction, and real estate for as-built documentation and space measurement.
Body and face scanning: At closer ranges (0.4–1.0m), the sensor could capture body and face geometry with sufficient resolution for 3D printing, avatar creation, and medical measurement. Apps like itSeez3D used the Structure Sensor to produce full-body and head scans as textured 3D models.5
Object scanning: Small objects on a tabletop surface could be scanned by rotating them or moving the sensor around them, producing detailed meshes for product design, 3D printing reference, and AR object tracking.
AR depth sensing: For early mobile AR developers, the Structure Sensor provided real depth data — enabling occlusion and physics against real surfaces — years before ARKit's LiDAR integration made depth sensing a native iPhone feature.
Structure SDK
Occipital provided the Structure SDK with the device, offering access to depth frames, the colour-depth alignment, and built-in SLAM-based room reconstruction. The SDK was compatible with Unity and Unreal Engine and provided OpenNI-compatible depth streams for developers integrating with standard computer vision pipelines.2
Structure Core (2019)
Structure Core was Occipital's second-generation depth sensor, released in 2019 as a standalone device — no longer dependent on an iPad. It combined a ToF-based depth sensor with stereo cameras and an IMU, capable of running Visual-Inertial Odometry for 6DoF tracking without a host device.3 Structure Core was aimed at robotics, autonomous systems, and industrial AR applications requiring self-contained depth and tracking.
Legacy
The Structure Sensor occupied a unique position in the 2013–2017 window between the Kinect's desktop-tethered depth sensing and the eventual arrival of depth sensors in consumer phones. It gave early AR and spatial computing developers a mobile depth sensing platform for prototyping experiences that would later be enabled natively by ARKit and ARCore. Applications and techniques developed with the Structure Sensor directly informed the design of the ARKit Scene Reconstruction pipeline that shipped with LiDAR-equipped iPhones.
See also: Hardware · Microsoft Kinect · Scene Reconstruction · SLAM · ARKit · Depth Sensing