News
 Street
Smarts: Improving Location-based Services with
Geocoding
By Matt Zarem, product manager of Autodesk's
Location Services Group
Information or Misinformation?
It happens all the time in action movies: the police
have planted a homing device on the culprit they are
pursuing. Having determined the exact whereabouts of
this nefarious individual, they rush over to his
lair and break down the door...only to find that the
lair is empty, and the criminal is nowhere to be
found. Only a blinking red homing device remains
behind, mocking them. The police's information has
misled them.
Any industry that utilizes LBS (location-based
services) has experienced this type of
misinformation to some extent. Take, for example,
the plumbing service that wants to locate its field
workers while they're out on service runs. Often the
precise street address displayed for a worker is
actually that of the center of a large region of
location, uncertainty, or that of the nearest cell
phone tower, not for the worker. The variance
between the two locations could be more than a mile.
This misinformation can be traced to the traditional
reverse
geocoding technology that has historically
underpinned LBS. Traditional reverse geocoding works
by analyzing a street network model database and
associating a latitude and longitude coordinate with
the nearest street network link. The location is
then returned in the form of human-recognizable
addresses.
So far, so good. But these traditional methods
become rudimentary and increasingly imperfect when
we apply them to coordinate locations that have
varying levels of uncertainty associated with their
accuracy. Uncertainties can be caused by a variety
of factors, from the quality of the GPS chip being
used, to interferences like tree cover, to whether
someone is indoors rather than outdoors.
Regardless of the cause, the end result is always
the same: misleading information can result from the
use of traditional reverse geocoding to return
addresses for locations that have relatively
significant inaccuracies associated with them. This
becomes a real problem when that misleading
information is then used by the system for further
processing, or by the end user. For example, our
plumbing service might dispatch a worker to a
customer site, thinking he is much closer to the
destination than is actually the case. Potential
delays - and unhappy customers - await him, due to
the faulty information.
Enter Autodesk's IRG (Intelligent Reverse
Geocoding). Coupling intelligent heuristics with
traditional geocoding, IRG returns address results
that better reflect the various inaccuracies
associated with locations.
IRG is the brainchild of Autodesk's location-based
services division. A spin-off of Autodesk's
geospatial software division, the LBS group saw an
opportunity to apply its knowledge and experience
toward addressing some of the challenges the
industry faced when communicating location
information. The following example illustrates the
difference between traditional reverse geocoding and
IRG. Let's say that you'd like to know if your child
is on her way back home from a movie or is still in
the theater.
Traditional reverse geocoding returns her location
as:
• 111 Las Gallinas Ave. San Rafael CA
You're led to believe that your child is at this
specific address. In actuality, this is the street
address of the serving cell tower's location—which
is about a mile and a half from the theater. You
don't know where "Las Gallinas Ave”. is, and you're
certainly not thinking about cell towers. So much
for feeling more informed—or more relaxed—about your
child's whereabouts.
IRG, on the other hand, returns her location as:
• Within 2 miles of Northgate Mall
Rather than being misled with highly specific—but
inaccurate—street addresses, you're informed that
she's been located near this recognizable location,
which is a well-known landmark in town and a much
more accurate description of her location. You
breathe a sigh of relief and go back to what you
were doing.
Under the Hood
A closer look "under the hood” demonstrates how IRG
arrives at this type of meaningful result. For
starters, it introduces a set of defined rules that
are used to determine how the geocoder should
behave, based on the characteristics of the source
coordinate information. Characteristics include—but
may not be limited to—location uncertainty
information and proximity to the nearest street
network link or point of interest. Coordinate
information converted by the intelligent reverse
geocoder into a human-recognizable format can take
the form of anything from a street address with
civic number detail, to a city name or a nearby
point of interest. The format returned to the
application is that which best considers the unique
and dynamic characteristics of the source location.
The result of all this sophisticated technology is
that users and applications alike are returned with
valuable information that more accurately reflects
the integrity of the original source location
information. And the more meaningful the
information, the more actionable and usable it is to
the user.
News You Can Use
It is this very quality of providing "news you can
use” that makes IRG so valuable. Far from being
“technology-for-the-sake-of-technology”, IRG has a
direct impact on improving the communication of
location information—and making misleading
location-based information a thing of the past.
The availability of more accurate information, in
turn, leads to better usability, wider acceptance,
and increased adoption of location-based services.
This is good news for the wireless network operators
who are looking to offer the next generation of
these services—but it's even better news for
consumers who have been looking for a compelling
reason to use them.
---Source:
Reprinted from Directions Magazine Jan 31, 2007
www.directionsmag.com. Matt Zarem can be reached at
matthew.zarem@autodesk.com.
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