Occipital Structure Sensor Review

Occipital bills its Structure Sensor ($379) as the first 3D sensor for mobile devices. This small gadget, which clips onto an iPad, provides depth data for true 3D imaging. It can act as a 3D scanner, and there are currently a few apps for the Structure Sensor that let you use the device for scanning and mapping, as well as virtual reality gaming. It's intended largely as a platform and playground for software developers; down the line, when more apps are available, it could have considerable consumer appeal.

Anatomy of a 3D Sensor
The Structure Sensor is an anodized aluminum device that measures 1 by 4.5 by 1.1 inches (HWD). Our test unit was ice blue; it's also available in silver. It is fastened with four screws to a bracket that fits on the iPad. (I tested the Structure Sensor with an iPad Air ($389.99 at eBay) ; it is also compatible with the 4th generation iPad and the iPad mini with Retina Display. The bracket for each model is different, and you choose the appropriate bracket at the time of purchase.) The bracket has a clasp to lock it in place, and a hole through which your iPad's camera can see and collect data.

The device uses a process known as structured light, in which an infrared laser projector casts a specific pixel pattern on the scene in front of it. The Structure Sensor's infrared sensor then records distortions in this dot pattern at VGA resolution as you move your iPad around the object you're scanning, creating a depth (3D) map of the scene and the objects in it. (The Structure Sensor's infrared detector was developed by PrimeSense, now owned by Apple, which designed the 3D sensor for Microsoft's Kinect.) The device also uses the iPad's camera, to record color data.

There's a Lightning cable included that's just long enough to plug into the iPad's Lightning port. The Structure Sensor has its own internal battery, and comes with a power adapter for charging.

The $499 version of the Structure Sensor comes with a USB "hacker cable," which lets you use the device with a laptop or desktop computer or other USB device (though you lose the benefit of the iPad's camera). It also bundles in the Skanect 3D scanning program for Windows or Mac that can receive data from your iPad, either wirelessly or over the hacker cable.

Occipital's Apps
Occipital offers several free Structure Sensor-related apps for download from the iTunes Store; most are designed to show off the device's ability to developers, for which the company provides an SDK. Although the company has focused on the device's use with the iPad, it can also be used with Android devices, and Occipital is offering open-source drivers, open CAD specs, and the hacker cable for use on other platforms.

The device's main app is called Structure. It offers three data streams to view: IR, which provides solely infrared data; Depth, which shows you a false-color view, with the nearest objects displayed as red, distant objects as blue, and objects of intermediate distance shown in varying shades of orange, yellow, and green based on their distance from the sensor, and tells you the distance (in centimeters) to whatever object is at the center of your screen; and Depth + Color, which combines true color with false color based on depth. In addition, it gives you information on firmware, serial number, and how much charge is left in the Structure Sensor's battery.

With the Structure app, seeing your surroundings on your tablet's screen as imaged through the virtual eyes of the Structure sensor plus iPad is a fascinating and surreal experience. It helps you appreciate the 3D-sensing capabilities of the Structure Sensor.

Virtual Physics
The other apps I downloaded deal with virtual reality (VR) and physics. The Fetch app involves a skateboarding cat trying to reach a yellow ball; the app is designed to show off the platform's VR gaming potential. First, you scan a portion of your surroundings—including interesting foreground objects if possible—and your real world will become part of the game's virtual reality setting. For example, the cat can't move through solid, real-world objects in its pursuit of the ball.

A similar app, Ball Physics, lets you launch virtual balls into a representation of a real-world scene that you've already scanned. When they hit the virtual representation of a physical object (such as a colleague's Rocket Raccoon action figure), the balls bounce off it on a realistic trajectory.

The Scanner app lets you scan a scene in 3D, and then view it in X-ray (see-through) mode or in Mesh (as solid object) mode. You can email the 3D file from within the app.

Finally, the Viewer app lets you see your surroundings in three views simultaneously: a Camera (realistic) view; a Depth view, in which surfaces are color-coded according to their proximity to you; and a Surface normal view.

Viewed together, these apps demonstrate the types of data streams that the Structure Sensor offers, as well as the device's application to both 3D scanning and mapping, and VR gaming.

A Third-Party Scanning App for the Structure Sensor
The first third-party iPad app for the Structure Sensor in the iTunes Store, released in late July, is itSeez3D, a scanning app that can scan both objects and human headshots in 3D. In our testing, it did a credible job at 3D scanning, particularly in scanning people, and its files can be uploaded from the app to a 3D model site or emailed. To 3D print the file, you must then open it with your 3D printer's software. We did some 3D scans of people using the app and then printed them out on a MakerBot Replicator 2X($3,856.95 at Amazon), with generally satisfactory results.

If you're looking for an iPad-mounted 3D scanner, you might also want to check out the 3D Systems iSense ($499), which pairs the Structure Sensor as hardware with 3D Systems' own scanning software (also used in the company's Sense 3D scanner), and can also use apps designed for the Structure Sensor. It's a particularly good choice if you own a 3D printer in 3D Systems' Cube line. You pay more money than if you were to buy the Structure Sensor separately, but iSense is designed to integrate with Cube printers such as the 3D Systems Cube 3D Printer($1,299.00 at Dynamism), and you get the ability to directly upload 3D files to Cubify.com for printing through the cloud.

The Occipital Structure Sensor is a 3D sensor that integrated seamlessly with the iPad in our testing. It's geared to software developers, although there are several available apps that can be used for 3D scanning by artists or 3D printing hobbyists. Down the line, when a wider range of apps have been created for it, the device could become popular with gamers and a more general audience. Until then, it provides developers with the opportunity to create apps for a low-cost 3D sensor with great potential. I, for one, can't wait to see what they come up with.