A Mountain of Data

November 1, 2007
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The Crazy Horse Memorial face rises nine stories high and was unveiled at ceremonies marking the project’s 50th anniversary in 1998.


POB has covered the historical carving of Crazy Horse with articles in 1991 and 1996. Beginning in 1948 with a ceremonial first blast, the carving of Crazy Horse has benefited from advances in surveying techniques over the years. Last year, Trimble 3D scanning was used to capture details of the entire mountain and to provide accurate data to fine-tune the mountain carving. Here’s the story.

The world’s largest mountain carving is being blasted into existence in South Dakota’s Black Hills: the image of Crazy Horse, the Native American Lakota Chief. When complete, the rock figure will rise to a height of 563 feet and a length of 641 feet, a stone colossus of the renowned warrior astride his horse with his arm pointing toward the sacred hills below. “My lands are where my dead lie buried,” he is reputed to have said. At the Crazy Horse Memorial, his history and vision are reborn as a monument to the heritage of the Native American Indian.

Often compared to Mount Rushmore, the work in progress marries the fine arts to explosives (a single blast can remove a rock mass 100 feet long, 20 feet tall and 8 feet wide) as well as engineering and high-tech surveying. Last October, two Trimble (Sunnyvale, Calif.) surveyors spent one and a half days on the mountain face, which lies outside Custer, S.D. Each using a Trimble 3D scanner, the two surveyors collected 14 million data points, which, after off-site post processing, became an invaluable tool for moving the project forward.

“For the first time in our history, we’ve been able to scan 95 percent of the mountain,” says Rich Barry, engineer with the Crazy Horse Memorial Foundation. “We’ve been collecting data and acquiring the tools to perform the tasks before us as the opportunities arise. The scanning was the next step in actually measuring the mountain in 3D.”

It’s “a project of Biblical proportions,” says Trimble surveyor Bruce Hook, part of the team that worked on the rock face in October. Conventional data collection techniques cannot adequately provide the volume of data required to drive the ever-more-refined blasting and shaping process in a project this huge. Enter 3D scanning, which collects, as Hook observes, “an almost unfathomable amount of data quickly and accurately.”

“Due to the magnitude of the mountain, you wouldn’t dream of surveying it today with only conventional equipment while maintaining the speed and accuracies you need to cover the range and size of the carving in a timely manner,” Hook says. “It would take years to cover the entire mountain using conventional survey equipment. With scanning, we can pinpoint a crack in the rock at a micro level and on the macro level a full model of the huge mountain as well--all in a matter of days.”

In fact, most of the surveying work to date has been completed with conventional equipment, only updating data over the years as technology has advanced. But the monumental endeavor didn’t benefit from surveying until later in its history; it all started with just a marble model and a jackhammer.

Surveyor Bruce Hook monitors the progress of a scan using the Trimble GX 3D Scanner.

The Endeavor Begins

In the mid-1940s, a young Boston-reared sculptor named Korczak Ziolkowski was recruited by Lakota Chief Henry Standing Bear to move to the Black Hills and take on the project of Crazy Horse. “My fellow chiefs and I would like the white man to know the red man has great heroes also,” the chief told Ziolkowski, who had briefly worked as an assistant on Mount Rushmore and held a lifelong dream of carving his own mountain.

In 1946, Standing Bear and Ziolkowski chose the 600-foot-high Thunderhead Mountain as the location for the immense memorial and the sculptor purchased land nearby with his own money. Initially living in a tent on his land in 1947, Ziolkowski carved from marble a model at a 1:300 scale of the mountain sculpture he envisioned. He personally hand-drilled the four bore holes for the first dynamite blasts in the rock face in 1948. It was a primitive operation: Ziolkowski’s jackhammer was powered by a gas compressor at the base of the mountain, with a 2,040-foot pipeline running in between. By the end of 1949, he had blasted almost 100,000 tons of rock off the mountain.

His dedication compensated for the lack of sophisticated equipment. With help from a small contingent of volunteers, Ziolkowski hacked out roads and hand-carried 29 tons of lumber for the construction of a 741-step staircase to the mountaintop 6,568 feet above sea level. Gradually, the operation expanded: an electric compressor was added, an aerial cable car and a bucket set up, and a bulldozer acquired.

By the time the sculptor-builder began operating his own lumber mill in 1959, more than a million tons of rock had been cleared from the mountain. In 1964/5, he created a 1:34 plaster model, which is used today for detailed finish carving. With the passing of a few more years and a few more tools--including electricity, a 26-ton moveable four-story scaffold, pneumatic trac drill and a huge drill-compressor--Crazy Horse’s face was beginning to peer out at the surrounding hills.

Three-dimensional scanning is ideal for a colossal job like Crazy Horse.

Driven by Dedication

It wasn’t until 1975 that a topographic map of the mountain and nearby land was developed by two local firms. Using aerial photography as well as theodolites and electronic distance meters (EDMs), the topo map was used to design sewer systems and additional roads for the growing project.

All the while Ziolkowski was fighting the consequences of serious health issues: a series of spinal operations and a pair of heart attacks. In the late 1970s and into the start of the next decade, he supervised the start of blocking out the horse’s head, 22 stories high. But several months after undergoing quadruple heart bypass surgery in 1982, he died at age 74.

His family has kept on with the project: “I wouldn’t have known what else to do,” says Ruth Ziolkowski, his widow and CEO of the Crazy Horse Memorial Foundation. “I was there when Chief Standing Bear’s letter arrived at Korczak’s home in Connecticut--and that was in 1939.”

The couple had 10 children, all of whom live on the memorial property or just four miles away in Custor. Seven of the children work at the memorial. Son Casimir is foreman on the rock face. Going back to the mid-’80s, daughter Monique has been intimately involved with the manual pointing system, which for years was the primary method of collecting data and scaling it up to the full-scale carving on the mountain.

Starting in 1987, the 1:34 scale model face was manually digitized and the coordinates transferred to the mountain by using a pointing system derived from the ancient Greeks. With pointing devices--each using east and west degrees, deflection and a plumb bob--on both the model and the mountain, thousands of measurements were taken of the plaster cast of the face, which was divided into 1-inch by 3-inch quadrants. There were more than 10,000 points on the face, 2,000 of them on the nose alone--all transferred to corresponding quadrants on the mountain, each measuring 3-feet by 6½ feet, to guide the carving of the face.

The great face, nine stories high, was unveiled at ceremonies marking the project’s 50th anniversary in 1998. Today the Crazy Horse Memorial attracts more than one million visitors each year. The 1,300-acre memorial complex also includes the Indian Museum of North America, the Native American Cultural Center and Ziolkowski’s log cabin studio home.

Remarkably, it is a non-profit enterprise, which depends on private philanthropy. The project itself has no scheduled completion date, but continues to benefit from refinements in surveying techniques, computer technology and explosives. With every blast, seismograph readings are taken and analyses conducted to ensure that the integrity of rock remaining on the mountain has not been compromised. To date, more than eight million tons of rock have been meticulously blasted off the mountain.

Crazy Horse engineer Kevin Hachmeister and Trimble surveyor Bruce Hook use the Trimble GX scanner to gather surface information on the steep rock faces of the Crazy Horse Monument.

Applying 3D

Three-dimensional modeling became significant to the project in the late 1990s. CAD models enable the translation of points from Korczak’s model to the mountain and facilitate more accurate rock removal.

Because of its speed and volume of data collection, 3D scanning is ideal for a colossal job like Crazy Horse, covering an entire mountain-in-the-round in intricate detail. The October scanning project used a portable Trimble GX 3D scanner, which allowed users like Hook to access points in shadow. Hook, carrying the unit and tripod up the face of a cliff, did this more than once at the Crazy Horse site. “I can show you some gnarly photos,” he jokes.

Hook used a combination of standard station setup routines over known marks and resected station setup routines, enabling him to both tie into existing control and establish new ground marks. The Trimble GX scanner enables surveyors to use conventional survey techniques such as known point station setups, resections and traverses while conducting routine survey checks to ensure the quality of their measurements in the field.

As the mountain’s face is ever-changing, there were only a few permanent marks on which to set up. In performing the resections, Hook was able to set up on new marks to maximize visibility into difficult areas, which ranged from sheer rock faces, to tunnels, to intricate carved features and shadowed areas. He selected the new marks and sighted two known marks in order to establish an orientation and typically used backsight distances around 300 feet or so depending on the conditions on the mountain. When confronted with challenging atmospheric conditions caused by fog and dust, Hook used the scanner’s video zoom capability to sight to the backsight targets. By adopting this resection technique, there were very few limitations to areas the scanner could reach.

After an orientation was gained, the scans were performed, producing valuable information from areas where there was high interest in the surface data. For the majority of points, four measurements were taken to every point (points averaging) to lower the standard deviation of the distance measurement. This ensures quality data with minimal noise, while also maximizing the amount of data captured.

This points-averaging technique was also vital as setups often required data to be captured at very narrow angles of incidence. These included narrow incidence angles within the vertical field of view for shots taken to the sheer rock walls and down into shaded regions or when inspecting tunnels--as well as horizontally along rock faces and flat portions of the mountain.

It was not always possible to set up the scanner with an ideal perpendicular view of a surface. But by increasing the number of shots taken, Hook was able to increase the amount of data collected while minimizing the amount of setups required. Scanner coverage was increased while making the most efficient use of the available field time.

“This flexibility in controlling the job was essential for this project,” Hook says.

A Model Refined

To aid in data post processing and to increase the data richness, Hook and his partner also took digital snapshots with the scanner. These can automatically be draped over points and surfaces (meshes, for example) in the office to gain a better understanding of surface conditions.

Post processing with Trimble Real-works Survey software allows the team to easily handle and analyze massive data sets to efficiently create desired outputs to the design team to guide the carving of the mountain. For example, the rich scan data revealed fissures in the rock face, necessitating fine adjustments to Ziolkowski’s scale model. That 60-year-old model, fashioned by hand, now lives digitally inside the rocks and can be continually fine-tuned; the software provides a 3D model of the mountain so accurate that it facilitates the model’s steady refinement in response to changing geology exposed by ongoing blasting.

As geologists, engineers and blasters continue their work, the model is refined, then scaled back up to the mountain face for more finely tuned blasting of the image. With the help of advanced surveying technology, the mountain is better adjusted to the model--and the model to the mountain. All the while, the imposing image of Crazy Horse continues to emerge in the sacred hills.

Six decades after moving to the Black Hills with her husband, Ruth Ziolkowski, now 81, is inspired by the project’s progress. “Whenever I can,” she says, “I go up on the mountain and walk out on Crazy Horse’s outstretched arm; you turn around and you look at him, and he’s looking at you. Well, the hair on the back of your neck stands up and it’s just kind of an amazing feeling … he’s up there watching over everything.”

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