Setting the Pace in Regensburg

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Bavaria has big plans regarding the collection of structural data from its towns, cities and municipalities. The largest of Germany’s 16 states, Bavaria is steeped in history and is home to cities containing modernized residential areas as well as historical districts with structures that date back centuries. Over the next few years Bavaria wants to update its data archives with new data on streets, buildings, landscape areas and street furniture with the help of a major project called "3D Visualization of Public Roads and Building Facades."

Collecting data in urban areas presents challenges due to concentrations of people, buildings and infrastructure. Traditional survey methods in urban areas can have inherent logistical complications that often grow as the size of the project increases. In order to assure the safety of the surveyors, the manual collection of data on buildings and street furniture often requires the partial closure of roads. This makes a survey conducted by foot costly and time-consuming. In Germany, conducting terrestrial surveys is still the principal means of gathering data for many cities and towns. However, one city is taking a break from traditional methods, deciding instead to "go with the flow." The city of Regensburg, a landmark city of Bavaria and the capital of Germany’s Upper Palatinate region, has adopted a method that allows surveyors to conduct field work from the comfort of an automobile.

The state-wide project is focused on mapping cities for tourism as well as technical functions such as engineering, maintenance and infrastructure management. By using a high-resolution 3D model, anyone can see what it’s like to drive through the historical neighborhoods of Bavaria. What’s different about the city of Regensburg, however, is that it’s all being done with a mobile spatial imaging system. The survey company Cloud-Vermessung will completely digitize the city’s public roads and building facades. An existing 3D model will be used to help organize a new model built with the data collected by the mobile spatial imaging system.

From an engineering perspective, there are abundant benefits of the 3D model. The new data will produce 3D representations of streets, buildings, landscaping, signs, and street furniture. In fact, Regensburg is going a step further than other cities by texturing the facades of historical buildings in the city center. The texturing process is achieved through coloring of the point cloud. The city’s engineering department can then assign attributes to surface elements. For example, crosswalks or bus stops can be identified and a road can be assigned its proper size and class. The complete public road space including parks and bicycle paths can be identified so that existing facilities can be inserted directly into the city land-use plans. When the project is complete, planners will be able to use the 3D model to visualize proposed new buildings in context with existing buildings and structures.

The texturing of the model also provides a record of facades and shop windows. City treasurers can then have an accurate view of the facades at their disposal. The city will have complete, date-specific information on its environment to help answer future questions concerning on-site conditions. And by identifying obstructions or low-clearance areas such as bridges or wires, the model can assist in mitigating road hazards.

The mobile unit uses a Trimble MX8 mobile spatial imaging system, which is mounted on the vehicle. The instrument is composed of seven high-speed cameras and two laser scanners. During the ride an integrated navigation unit records the position and orientation of all the equipment. The system captures and geocodes one million points per second; the number of photographs taken depends on the vehicle’s speed. To meet the demands of this project, the vehicle can travel at regular speed limits so no special arrangement for traffic control is needed.

The field work is completed as soon as the ride is over. Processing can take place back at the office, where Trimble Trident software goes to work and the collected images are overlaid with a 3D point cloud. The new 3D point cloud can be adjusted to match with existing data, which increases redundancy and improves the overall quality of the project. When a project is completed, deliverables can be exported in various GIS or CAD file formats, enabling Cloud-Vermessung General Manager Frank Pöhlmann to transfer the data to the city of Regensburg in the format they require. There is no need to switch systems or train the staff on new software. "The city treasurers may use the data to seamlessly generate textures for facades and update their maps with their own system," Pöhlmann said.

At the project’s conception, the city was concerned about whether the results of the mobile mapping were as good as terrestrial measurements. In order to check the accuracy of the results obtained with the Trimble MX8, road markings measured by the mobile system were compared with terrestrial measurements. The city was pleased to see the positional accuracy of the data collected by the mobile unit agreed with the terrestrial measurements by about 4 cm (1.6 in). And due to the shorter project time and reduced safety costs compared to terrestrial surveys on a roadway project, the mobile data collection is an investment that can be amortized quickly.

Although the project’s completion is still a couple of years away, Pöhlmann has already concluded that the project is unique throughout Bavaria and will meet the accuracy requirements 100 percent. "All in all, the Regensburg city planning office is rather well prepared for the future," he said. When it comes to mapping infrastructure, this east Bavarian city is setting standards that encourage others to follow in its tracks.

Gordon Wilson graduated from the University of Maine at Farmington in 2010 with a creative writing degree. He currently works in the field crew at Titcomb Associates in Falmouth, Maine and manages

A 2.636Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE