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New Navigation App 'Live Roads' Promises 1.5m-Accuracy With Standard Cellphone Hardware (arstechnica.com)
Jonathan M. Gitlin from Ars Technica reviews a new navigation app called Live Roads, which promises 1.5m-accuracy via your current smartphone without the need of any extra hardware. In a nutshell, the app provides more accurate mapping/navigation than what's currently available via Google Maps or Apple Maps, but it's still not quite as accurate as a true "HD map." HD maps are accurate to within a centimeter or two and are usually made by a combination of traditional surveying and lidar scanning. Here's an excerpt from the report: A few weeks after talking with the company, I was delivered a Samsung S7 loaded with Live Roads. I'll be honest: I'm not that familiar with Android, and this isn't really a review of the app. I used it enough to check that it does what it claims, but I didn't use it as my sole method of navigation. However, this brief bit of user-testing did let me check out the claims in that email. I don't think I'd equate the app with the HD maps that autonomous vehicles will need. For one thing it's readable by a human being; for another it's not quite that accurate. But the spatial resolution was indeed better than it should be on a consumer phone, and Live Roads was able to locate me down to a specific lane on a multi-lane road. Various navigation apps give you lane-specific instructions -- for instance, telling you to stay in the middle two lanes if you're approaching a complicated intersection. Where Live Roads differs is that it can also tell which lane you're actually in. Whether this is enough of a feature to build a business model around is an open question; I'm quite happy using Google Maps on iOS, with occasional forays into Waze (running in the background to warn of speed traps) and Apple Maps (if I'm driving something with CarPlay and the infotainment's built-in navigation sucks).
But it left me wondering: how does it work? Paul Konieczny, CEO of Live Roads, gave me an explanation -- up to a point. "Primarily it is based around sensor fusion and certain probabilistic models -- we call it the Black Box," he said. "The current release of the app that is available in the Play Store has an earlier revision of our Black Box. This initial version is missing some of the functionality of the full-fledged system and thus has a spatial resolution of ~2.5m. This compares favorably to standard GPS that has a resolution of 4.0 m+." By summer, Konieczny hopes that the system will be fully operational and that accuracy will be down to under 1.5m. Assuming a large enough user base, that should let it offer lane-specific traffic data, "as well as introducing an entire ecosystem of 3D objects that users will be able to interact with," he told me.
But it left me wondering: how does it work? Paul Konieczny, CEO of Live Roads, gave me an explanation -- up to a point. "Primarily it is based around sensor fusion and certain probabilistic models -- we call it the Black Box," he said. "The current release of the app that is available in the Play Store has an earlier revision of our Black Box. This initial version is missing some of the functionality of the full-fledged system and thus has a spatial resolution of ~2.5m. This compares favorably to standard GPS that has a resolution of 4.0 m+." By summer, Konieczny hopes that the system will be fully operational and that accuracy will be down to under 1.5m. Assuming a large enough user base, that should let it offer lane-specific traffic data, "as well as introducing an entire ecosystem of 3D objects that users will be able to interact with," he told me.
I think he meant precision.
Well, I'm not overly familiar with iOS, so I'd add a disclaimer if I was reviewing an iOS app. I'd expect someone who's primarily an iPhone user to give a similar disclaimer when reviewing an Android app. Same for a Mac user reviewing Windows software and vice versa.
I'm not really sure...I think it may be you who doesn't know what those terms mean. Accuracy is how close your measurement is to the correct value. Precision is how much variance you have between multiple measurements. This article talks about being able to identify correctly which lane you are actually in, which sounds like accuracy to me.
I assume in the process they are also increasing precision of the readings, too. They are probably cross referencing accelerometer and compass data with high resolution map data over time. Doing things like noting when you make a 90 degree turn, that you must've been in the center lane or right lane at that time and using future accelerometer readings to track future measurements relative to the guessed lane. This would result in multiple readings of the same position to reach the same determination of your specific spot, which would be increased precision. But that is just a side effect of the goal to improve accuracy.
The difference is that a Garmin has 12 receivers and a standard cell phone has 3. 3 receivers is the minimum that you need to find your position but it is only accurate to about 150 feet. What I believe this software package is doing is storing additional 3 GPS satellites frequencies in memory and switching between the two sets of 3 frequencies as fast as it can to get to 1.5 meters or around 5 to 7 feet.
With 12 receivers, you only need 12 because of the 24 GPS satellites, 12 of them are going to be on the other side of the earth, you can get the 3 cm resolution you need/want. I've been using my bicycle Garmin for more than 10 years when a standard smart phone would tell you what road you were on, the Garmin would tell me what side of the road I was on. I can also use it for driving and would easily tell me what lane I was in, even 10 years ago.
People that are not used to 12 receiver GPS's are amazed of the resolution that a 3 receiver GPS will give when a software trick is used to make 3 receivers 6.