Lenovo Phab 2 released summer of 2016 is the first phone with Googles Tango 3D augmented reality system. This is currently the only phone model with the tango system until Asus Zenfone AR is released in the second quarter of 2017).So what is Tango 3D AR. Tango was developed in Googles ATAP’s skunkworks group. The development team was headed up by Johnny Lee, which previously worked on Microsoft’s Kinect. Tango will allow you to record and map a 3D environment using the onboard 3D camera. Only a handful of Apps are currently available for Tango. These apps include MeasureIt(for measuring objects), roOomy Reality that enables you to visualize furniture placements, Tango Constructor an experimental developer app that demonstrates selected features of Tango. Tango Towers where you build a 5 star 3D tower in AR.
These only scratch the surface of the potential for AR using a phone hand set. Future applications will include building and landscape visualization in real-world settings. Applications to map in 3D using the 3D camera, systems GPS, gyroscope and accelerometer.
Engineers at the University of Texas at Austin have now developed a cheap GPS system. Using a $5 antenna and software they developed and a Samsung Galaxy phone they were able to map in 3D accuracy of two centimeters. The development team now has a startup, Radiosense LLC, to further evolve the technology. They are working with Samsung to develop a low cost snap-on system, which will contain the antenna and software-based receiver. They say that the receiver should eventually be for sale at less than $50.00.
If you are considering smart phones or tablets for field data collection you probably have this question. You should also be be asking how much accuracy you need in doing your job, and is this better than your current method.
Survey grade GPS, like this Trimble R8 above, has accuracies of about 2 cm and a price tag of thousands of dollars. Fortunately this level of precision is not needed for most field jobs. I you are trying to locate a utility pole, map the boundaries of a wetland, map facility locations or locating addresses accuracy of 5 – 10 meters is probably adequate.
How Accurate is a Smart Phone GPS
I have seen many claims on the internet that cell phone GPS receivers had accuracies no better than 10 meters. Those claims are out of date and misinformed. Most modern smart phone GPS receivers come with several advanced features that improves speed of acquisition and precision. They also use WiFi to indoor positioning.
First a little background about GNSS systems. A GPS receiver calculates its position by measuring the distance between several GPS satellites. The technique used to measure the distance is called satellite ranging, in which the distance is computed from the elapsed transmission time. The receiver then triangulates a position.
There are many sources of errors in GPS the largest being the ionosphere and troposphere distortions (refractions) of radio-signals. The total error for an uncorrected signal is 10-15 meters.
Cell phones use differential corrections to improve accuracies. Most incorporate SBAS (Space based augmentation systems) such as WAAS and ENGOS for corrections. Most modern cell phones also support GLONASS and other GNSS constellations. The additional space vehicles improves the satellite geometry reducing the Geometric Dilution of Precision. Cell phones GPS receivers are assisted, which means that the satellite ephemeris data is uploaded through the internet which results in convergence in seconds rather than minutes. The accuracy of cell phone GPS is 2-4 meters.
GPS Accuracy is 2-4 meters in most current models.
Future of GPS in Smart Phones
For smart phones a major obstacle to sub meter precision is the antenna. Smart phone manufactures have restrictions on size and budget for GPS antenna. Better patch antenna could reduce sign db loss and multipath error. An improved antenna could improve accuracies 1-2 meters. Texas researchers have developed software that could reduce multipath errors from the antenna. The European GNSS system Galileo will improve GPS position to sub-meter. Precision Point positioning (PPP) technologies could become available to smart phones improving precision to decimeter range. Increase by drone, VR and autonomous vehicles will push development of centimeter precision GPS. Prices currently for L1 centimeter precision has dropped below $500.00.