| November 03, 2011 |
Drive By Surveying
Rovers are great, but with Topcon’s IP-S2 you can now map out a site at 60 mph and never even step out of the truck.
By Tom Jackson
In the past 10 years the advent of pole-mounted GPS rover receivers have been a boon for contractors. You can record survey points on big earthmoving sites and enter them into digital CAD files almost as fast as you can stand the pole up and push a few buttons. Walking between the points takes a little boot time, but it sure beats waiting on a survey crew.
Now Topcon has come up with a vehicle-mounted GPS/GNSS survey system, called the IP-S2, that can record data/survey points and take 360-degree photo images of anything you want to measure as fast as you want to measure it.
And we’re talking 60 miles per hour, if that’s the speed you need.
The heart of the system is a dual frequency GPS/GNSS receiver. But to make the IP-S2 accurate at highway speeds in the back of a bucking pickup truck, Topcon adds two more components. An inertial measurement unit (IMU) measures the roll and pitch caused by the vehicle traversing over uneven terrain. And the rear wheels are outfitted with external wheel encoders that records odometry data (how far you’ve gone based on the diameter of the wheel).
Both these units send digital data to the IP-S2’s controller. The wheel-mounted systems tell it precisely how far the vehicle has traveled and the IMU compensates for the motion of the truck. These redundant positioning devices also help maintain an accurate vehicle position when bridges or buildings block your GPS/GNSS signals.
The final piece of the puzzle, the laser scanners, shoot out and record distances from the unit to objects along the route. This information is then combined with the vehicle position data to give you a highly accurate digital 3D map of everything the truck drives past – buildings, light poles, fire hydrants, curbs gutters, traffic cones, overpasses – everything.
The IP-S2 system also comes with a 360-degree digital camera that captures digital images of all these objects and syncs them to the 3D map as well. After completing your drive-by survey you take the data from your in-cab recorder, run it through a post-processing software, and plug it into your CAD program. The files can also be exported to handheld devices to check and reference data in the field.
The IP-S2 is probably overkill for a small contractor, and it costs a bit north of $200,000. But if you or your company write a substantial check to a survey company every month or so, on if you spend considerable time and resources doing your own surveys, then the system offers some unique advantages.
Mapping and surveys in urban locations and high traffic areas is rendered quick and easy. There’s no need for anybody to get out of the truck, so your guys are safer. And if you’ve got a large project such as a big section of highway to build, you can do the pre-construction survey, all the intermediate and final surveys in minutes, rather than hours. Or if a DOT official wants proof that something has been completed to a certain spec by a certain time – say all the traffic cones removed and a lane or lanes opened to traffic, he won’t have to drive to the site to check. You can just take a quick pass of the work with the IP-S2 and provide him with the file, typically on an external USB drive.
Richard Rybka, IP-S2 mapping specialist, says a lot of contractors who acquire one will likely offer the service to other contractors to get more use and a quicker return on the investment. Rybka also sees survey companies or individuals acquiring the IP-S2 to offer it as a subcontractor service.
DOTs, utilities and municipalities are also another potentially big market for the IP-S2 or the service it offers, Rybka says. In the aftermath of the floods, tornados and hurricanes of recent years, many of these organizations need an expedient way to map all their assets. With an IP-S2 survey, owners would be able to quickly establish a digital map of all their assets and upgrade, repair or rebuild damaged assets without having to do extensive and time consuming surveys through conventional means.
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