JetsonHacks

Intel RealSense Camera

Intel Realsense R200

The Intel RealSense Camera is a RGBD (Red, Green, Blue, Depth) camera which fits a large amount of imaging technology into a small package. Looky here:

Background

Over the last couple of years, we’ve had several articles about RGBD cameras. RGBD cameras provide a color image stream (the RGB part) and a depth stream (the D part) which can be used for a variety of imaging and robotic applications. In the video you saw how the mechanical packaging of these types of devices has changed over the years.

A couple of months ago Intel announced the Intel® RealSense™ Robotic Development Kit which includes a RealSense R200 camera, along with an Intel Atom x5 processor board. I thought that was interesting enough to order the kit from Intel. After all it had the word “robot” in the name!

At the same time, I am intrigued with the form factor of the R200 camera. This uses the same technology as the ‘Project Tango’ tablet (now called ‘Tango’), though without the fisheye camera. The R200 is available separately, and for a price of $99 USD it is certainly worth investigating. Will it run on the Jetson?

Please, you’re on this website. You know it will!

Technology

From the librealsense documentation:

R200 Component Layout

The R200 is an active stereo camera with a 70mm baseline. Indoors, the R200 uses a class-1 laser device to project additional texture into a scene for better stereo performance. The R200 works in disparity space and has a maximum search range of 63 pixels horizontally, the result of which is a 72cm minimum depth distance at the nominal 628×468 resolution. At 320×240, the minimum depth distance reduces to 32cm. The laser texture from multiple R200 devices produces constructive interference, resulting in the feature that R200s can be colocated in the same environment. The dual IR cameras are global shutter, while 1080p RGB imager is rolling shutter. An internal clock triggers all 3 image sensors as a group and this library provides matched frame sets.

Outdoors, the laser has no effect over ambient infrared from the sun. Furthermore, at default settings, IR sensors can become oversaturated in a fully sunlit environment so gain/exposure/fps tuning might be required. The recommended indoor depth range is around 3.5m.

In a little less techy terms, the camera appears pretty capable. The camera works outdoors (a big drawback to the indoors only Kinect/infrared types of devices), and multiple R200s can be used in the same physical indoor space without having to worry about infrared pattern interference. All of the depth processing and image registration is done in hardware on the camera, so there isn’t computational drag on the host computer. That is one of the drawbacks of the Stereolabs ZED camera, where the host processor builds the depth maps from the gathered camera images. That takes a large amount of compute cycles on a small processor like a Jetson TK1. The biggest thing of all? The R200 is small. For the amount of horsepower, the $100 price is a bargain in the current marketplace.

Software

Intel has made available an open source library, librealsense on Github. librealsense is a cross platform library which allows developers to interface with the RealSense family of cameras, including the R200. Support is provided for Windows, Macintosh, and Linux.

The next couple of articles on JetsonHacks will cover how to install librealsense on the Jetson TK1. This includes building a kernel with support for the cameras, along with installing the librealsense library. At this point, let’s say that this is a project for non-noobs.

Intel also has a ROS interface for the R200. There will be an upcoming article about installing the ROS interface too!

Conclusion

The Intel RealSense R200 is an interesting entry into the 3D imaging field. If sophisticated imaging robotic applications are to enter into the personal developer market (as opposed to corporate developer), this device will be one of the key enablers.