Deadwood scan

It was a bet not to record a historic area like Lawrence County's Deadwood, South Dakota. The city was named after the dead tree found in the narrow canyon [Deadwood Gulch], where the historic Main Street and Sherman Street were originally laid out. Covered by a narrow gorge of pine-clad cliffs surrounded by Black Hills, the entire National Historic Register city was ready for fire devastation. The National Historical Protection Association has put the entire historical district on the list of the 11 most at risk.

The lesson of forever losing past historical main streets throughout the United States has driven Deadwood's decision to “preserve” historic communities through documentation. It was a lesson learned hard when the city rose from the ash again as miners, merchants, bankers and saloon keeper began rebuilding in 1878. The city even felt the effects of the 1966 earthquake.

In the spring of 2003, Rapid City, South Dakota and other support team TSP Architects recorded a 5,992 foot building facade along the downtown main street about 0.5 miles on each side using a Cyrax 2500 3D laser scanner. did.

In the quarter-century after the great fire, Deadwood experienced an unusual architectural boom, and the gold-rich town created a sparkling Galimau-free style in the late 19th and early 20th centuries. The eye-catching version of Italians, Richard Sonian Romanesque, Second Reich, Queen Anne, and classic revival are now part of historic Downtown Deadwood. Many of the main street saloons, gaming houses and hotels have Italian characteristics, and some of the facades suggest a fake front that decorates a less important structure.

“With conventional documentation methods, it was not possible to show such structural details with elements of rough stones or decorative iron balconies,” said one of the original team members, now Optira, Inc. Says Mitch Schefcik. Carefully restored accurate documents on the reproduction of end-of-the-century buildings John Wayne, Pearl Buck, Babe Ruth, President Theodore Roosevelt and others have left this historic and unique Wild West town . . 3D laser scanning was the only clear option. “Optira, Inc., President and CEO Schefcik said.

In 2003, this technology was quite new. Cyrax 2500 maker, Cyrax 2500, “points the scanner at the scene, selects the desired measurement area and measurement resolution, and then automatically scans. The complete surface shape of the exposed surface is dense and accurate. “3D point cloud” is ready to use. "

“When creating documents using a 3D laser scanner, the importance of survey management is often overlooked,” said Michael Frecks, vice president of Optira, Inc. and 29 years of land inspector. “I felt it was important to involve local research companies in the area, not only for friendliness but also for commerce.”

Deadwood's unique coordinate system is another reason for being involved locally. Black Hills Surveying, Inc., Spearfish, South Dakota, was selected for this job. The region's history is one of the mining communities built from a coordinate system based on land information from the late 1800s based on the home steak mining company's open pit mine and the late 1800s land management office. Until the 1980s. In the early 1990s, the city of Deadwood passed the ordinance that established this system as the official coordinate system.

Randy Deibert, president of Black Hills Surveying, contributed to the establishment of more than 20 original monuments in the region, and comprehensive terrain on Deadwood Main Street for historical reconstruction scheduled in the early 1990s Created a diagram.

“The Deadwood coordinate system is an extension of the home steak coordinate system, including a monument in the mining district and a long history of the coordinates of hundreds of existing parcels,” Davert said. “The horizontal values ​​used this existing system to create an immediate GIS reference of the parcels. The vertical component is the result of the current FEMA benchmark used for regional flood floodplain management.”

Controls were placed along the main street, and an additional set of controls was installed within the historic United Methodist Church. The building was marked for demolition. The record of relationship and state with the district was the driving force for documentation of the entire main street. This dismantling proves to be a “test” scenario for pre-documentation purposes. The church was modeled in a 3D environment and virtually placed in the recorded scene using a laser scanner and surveying controls.

“Control traverse errors are directly related to the absolute position of the scan. However, since the scan has a relative accuracy of 0.5 inches relative to itself, there are especially 376 scan control points, Is very important. " Deadwood's highly detailed 244 scans each took about 15 minutes, and every 100 scan locations took about 30 minutes. To speed up the process, the team set up using two scanners facing opposite locations [northeast and southwest] simultaneously to control and capture the front of 77 buildings.

The Black Hills Survey crew was one day behind the scan team providing control. The main system used about 10 primary turn traverses and was controlled from the existing monuments of the local system. Additional side shots were also collected for all scan reference points above and inside the building. In total, the research side of the project took 8 field days, including a one and a half day delay due to rain.

Four scan targets were placed in each scan scene to associate scan data with survey controls. Each target was shot twice and an average value was assigned to the target. Once completed, the survey data was applied and the database was created with actual local coordinates.

This algorithm automatically calculates pair-wise registrations between individual scans, creates a topology graph, and places the scans in the same reference frame. You can extend these methods to automate the texture mapping process and create both geometric and photometric real models.

Since Deadwood's documentation, Optira, Inc has been at the forefront of historical documentation by catching up with the evolution of 3D laser scanning technology through the latest adaptation of 4D embedded metadata. These Building Information Modeling [BIM] processes are to acquire 3D building space data with high accuracy and short processing time, and place the data in the “living environment”. “Scans had to be done at a density that supported maximum data mapping at no cost,” Frecks says.

The Deadwood Documentation Project was partially funded by the CyArc Foundation, located in the San Francisco Bay Area, as a major pilot program. Since Deadwood's documentation, CyArc has evolved as an archive and related web portal, allowing site managers, researchers, students, and the public to access data.

“Conservation of cultural heritage is an important issue. These sites are subject to many forms of abuse, from erosion to vandalism, and have gone through many stages of construction, damage and restoration as long-lived artifacts. , Site administrators and conservation specialists can do a better job of cultural resource management, as a visualization technology, they allow more audiences to virtually see, learn and tour these sites Provides tools to help, "CyArk High Definition Network and father of 3D laser scanning.