Wherever You Go … There You Are
by Will Rourk
Do you know where your phone is? Well your phone knows where you are thanks to location awareness technologies inside your phone. If you want to know where the best restaurants or closest cafes are to your current location or what friends and colleagues are hanging out near you, then your phone can tell you so. Being aware of your place on the planet is something we’re quickly going to take for granted as location awareness becomes increasingly integrated into our mobile lives. The backbone of location awareness is GPS, a technology that not so long ago was mostly being put to use by the transportation and surveying industries. Oh, and also by hikers.
Today GPS is as ubiquitous as cell phones and automobiles, which is where you’ll find most popular consumer GPS technologies being used. But GPS technologies are literally all around us and cross the boundaries of our personal and professional lives. We can better understand the scope of GPS technologies through their consumer and professional uses. But first let’s take a brief look at what GPS technologies are all about.
The Global Positioning System, originally known as the Navstar GPS, is the United States’ GNSS, or Global Navigation Satellite System, a constellation of satellites that provide us with positional data in latitude and longitude coordinates anywhere on the planet. A GPS device can receive data from the satellites to tell you your position on Earth as long as it can access at least four satellites with an unobstructed line of sight. The U.S. has 30 working satellites in operation today. But more satellites would mean better chances of connecting to positional data.
According to Kelly Johnston, GIS specialist for geospatial research at the University of Virginia’s Scholar’s Lab, the big news in GPS today is that the Russian GNSS, or GLONASS, is now just as freely available to everyone in the world as GPS. “Now devices have worldwide access to U.S. and Russian position satellites to provide more points of access from satellites.” That is as long as you have a device that will receive GLONASS signals. Increasingly since 2011 most professional and consumer grade GPS devices are becoming capable of receiving GLONASS signals.
Accurately finding your position on Earth takes more than just satellite information. Professional GPS demands exact positional accuracy for site survey work. Bill Moore, president of Earth Vector Systems GPS, the main provider for Trimble surveying and mapping equipment and training in central Virginia, understands that GPS is not just a single device but a system of technologies.
“The measurement process is always contextual,” Moore says. “Reception depends on factors such as overhead canopies, satellite positioning and signal disruption or jamming. You need a sophisticated operating system to collect accurate data.”
A sophisticated professional system includes not just a GPS signal receiver, but can also include a base station for logging data remotely, a database for storing the data, and software algorithms such as Differential GPS (dGPS), that can derive more accurate positional data to the centimeter level. A practical example of this setup is a Trimble Geo series receiver working in tandem with a Net R5 base station to log and collect positional data accurately in the field. Using Virtual Referencing Systems, or VRS, Trimble devices can apply real-time data correction algorithms to provide a greater degree of positional accuracy in the field.
It’s technologies like these that allow engineering and construction firms to combine GPS technologies with BIM data for automated construction site work. Lasers can guide excavating equipment to provide equipment operators with extremely accurate data provided by a BIM 3D model. The operator uses onboard GPS to compare the amount of land excavated or graded with the BIM model of the site to levels of accuracy that exceed manual survey.
The consumer level of GPS has also taken on a more hybridized form as is evident with our GPS enabled phones. Just as Trimble professional GPS uses dGPS and VRS for deriving accurate lat/long positions, cell phone technologies rely on more than just basic GPS. Since 2011 most smart phones are now GLONASS receivers as well as GPS receivers. But in addition to greater satellite coverage, cell phones also use advanced positional technologies to help locate us.
Simultaneous GPS, or sGPS, does what its name implies. It allows GPS smart phones to receive voice data as well as positional data, allowing more sensitive reception as well as the ability of mobile service providers to allow more location based services. Assisted GPS, or aGPS, uses ground networks to provide extra information when conditions for GPS reception are not optimal. For example, this is why you can still find your position when you are inside a building or deep within an “urban canyon” where the density of tall buildings deflect or distort incoming GPS signals from satellites overhead.
Research in urban planning is examining how we can obtain a more qualitative location on the map than just an omni-directional lat/long position. Guoping Huang, assistant professor and researcher in Urban and Environmental Planning at the University of Virginia, is combining GPS with digital compass technologies to produce waypoints on a map that emphasize direction. A GPS waypoint usually only gives us a lat/long or x,y position on a map that is ambiguous to any one direction.
Huang sees the value in focusing on a particular direction as a way of measuring the visual quality of a location on a site. His idea is to develop a new positional locator point for ArcGIS, the main map making and analysis tool of GIS developers, that emphasizes direction so that you can load your points into a map project that includes directional data. This would allow planners to provide qualitative location information to those who “want to use this application for scenic value or manage visual resources over time.” Using geo-tagged photos, Huang collects visual references of a site into an ArcGIS map over the duration of the site’s development which is then published to the Web for public use and participation. Huang notes that “this will be a big improvement on the geotagging tool, those things you see on Flickr, where it just shows the point. The public wants to understand how the project will look like at different locations” and with this approach they “can publish geotagged photos of the site that emphasize location to show how the site changes over time.”
Huang’s specialized use of geotagged locations could have a big impact on geotourism. Map points with qualitative information based on direction of view would be a way to provide tourists with specific information on locations they visit. In fact, geotourism could very well be the nexus of professional and consumer uses of GPS technologies. Geotourism allows self-curated explorations of urban and historic landscapes. Guided by a GPS device, a tourist can be directed to specific locations with either a map of points or GPS coordinates loaded into their GPS receiver or smart phone. With an emphasis on direction, tourist focus can center on a view of an historic event or building. GPS-located points can include historic information, such as historic photos and media that describe a location in detail. Using professional GPS, placemark locations can be more accurately defined. With consumer-grade GPS, such as we have in our cell phones, those places can be accessed and explored in more meaningful ways. Location awareness becomes a two way street. Not only are we located more easily but we can become more aware of our locations.
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