April 3, 2008
Campus paint markings mean a new, georeferenced campus map is under way
Students come to the UW to find their place in the world. And in a way, that’s also what Facilities Services is doing for the University, with the creation of an absolutely true, accurate map of campus, referenced to its exact location on Earth.
It’s also why there were so many brightly painted manhole covers, white crosses and other markings on the pavement around campus in recent weeks — just in case you’ve wondered.
Simply put, it’s called the Campus Map Update–GIS Implementation Project and it is a comprehensive, state-of-the-art update of the campus base map, which, of course, dates back to the days before geographic information systems and global positioning. This Earth-true map can then be used as a foundation for future campus development, mapping and uncounted other applications.
The project has been under way for about two years, culminating with a series of flyovers on March 9 by a single-engine Cessna T210 taking photogrammetric images, the type used in surveying and map-making.
John Chapman, executive director, and Butch Kuecks, assistant director of Campus Engineering and Operations for Facilities Services, explained the process. But they stressed that the project involves many people working together, in Facilities Services, the Capital Projects Office, the Capital and Space Planning Office, UW Technology, the UW Real Estate Office and the Outside Maintenance Zone.
The UW has long created maps from aerial photos of campus, but those maps have never been perfectly accurate, for a number of reasons — from tiny errors resulting from topographical irregularities and combining maps for a comprehensive view.
According to a description provided by Kuecks, “The project will also update and expand the campus survey control monument network to insure future land survey, capital construction and GPS land data is coordinated with the new campus base map.” When completed, existing campus utility maps will be added to the database.
The manhole covers and utility locations were painted with industry-standard colors set by the American Public Works Association — red for electric power lines, green for sewers and drain lines, orange for telecommunication lines, blue for drinking water and yellow for natural gas or other flammable materials. White crosses are called “photogrammetric control points,” used for orienting the mapping for absolute accuracy.
For this project, the UW has contracted with Bush, Roed & Hitchings, consulting land surveyors based in Seattle, and Marshall GIS out of Olympia. Aero-metrics, the company that did the flyover, is a subcontractor.
Jim Crabtree, regional manager for Aero-metrics, said certain conditions were necessary for flyovers to be effective. They needed to be done before the trees leafed out, on a weekend so there were fewer cars and at this time of year when the angle of sunshine is best. The best weather, he said, is neither a sunny day nor a completely cloudy one, but “high, bright overcast” weather. Luckily, those conditions were met on March 9, and the flyover process was successful.
The Cessna needed to fly over the campus four or five times to get the whole area photographed, at an altitude of only about 1,550 feet. The images are orthographic — that is, aerial photos corrected to account for the curvature of the Earth. And they are detailed in the extreme, with sufficient resolution (a whopping 1,588 dpi) to pick up images as small as three inches by three inches.
Crabtree said the film was developed quickly, but it takes some time to abstract the needed information from the stereographic film. The mapping project is expected to be completed in late spring.
And then the map and its georefererences will be uploaded into a GIS database and made available to anyone wishing to use it. That means that however they use this data they’ll always know that their starting point was absolutely accurate.
And what of the spray-painted manhole covers? The paint is water-soluble, and much of it has already been washed away by another thing that denotes the UW’s place in the world — rain.
