A 5.132Mb PDF of this article as it appeared in the magazineâ€”complete with imagesâ€”is available by clicking HERE
The Mountain View Cemetery, located adjacent to Idaho State University in Pocatello, Idaho, is a relaxing place for a quiet walk; yet always stirs my sense of wonder with the lives and stories of those who lay beneath its soil. As a student at ISU I often walked among its tree-lined streets; watching the wind gently play with fallen leaves and gazing upon the cracked and weathered headstones of those long dead. The earliest section of the cemetery was platted in 1893 and many of Pocatello’s founding families are buried within its borders; pioneers, settlers, gold miners, railroad workers, city builders, statesmen and others who lived out their lives building our nation and taming the West.
One particular individual, James H. Brady (1862 Â 1918), was Governor of Idaho, a U.S. Senator and one of Idaho’s major entrepreneurial businessmen. Upon his passing in 1918 his wife and children built for him a beautifully detailed 30’x50′ memorial chapel. The chapel is designed in the Gothic Revival style featuring many buttresses, ornate finials and an outset archway around the entrance. The exterior is handcarved Indiana limestone, interior woodwork and entrance door of oak, colorful stained glass windows throughout and an original slate roof capped with an iron ridge along the peak. It was completed in 1922 and now serves as the cemetery’s centerpiece. It would also serve as the perfect subject for my senior project in the Geomatics program at ISU.
My deep fascination with early American history was a major factor in selecting my profession as a Surveyor. In seeking a fulfilling and life-long career which combined my interests of history, mathematics and the outdoors I enrolled in Idaho State University’s four-year Geomatics degree program in 2009. Students are taught everything from operation of levels, total stations and GPS systems, taking field notes, records research, CAD drafting, survey computations, legal principles, subdivision design, GPS theory, geodesy, photogrammetry, public land surveying and business planning. All of the instructors are licensed surveyors and students receive a lot of actual hands-on surveying experience with both field and office work.
In the final semester each student embarks upon a senior project of their choice, which when completed is presented to a panel of approximately ten licensed surveyors. This panel of surveyors grades each presentation and ultimately decides if a student will graduate from the program. For my project I knew I wanted to do something special and the Brady Memorial Chapel presented itself as the perfect opportunity. Through my project I was able to explore the fascinating history of Pocatello’s past, while utilizing cuttingedge technology of the future.
I began my project by digging through old records and plats at local county and city government offices. While many of the records I sought had disappeared through the cracks of time, the excitement of finding each new little piece of the puzzle kept me going.
After some hesitation the county records clerk allowed me to very carefully copy the field notes of the 1889 Townsite of Pocatello survey by U.S. Deputy Surveyor Samuel G. Rhoades. I enjoyed reading of his nightly Polaris observations with a primitive instrument outside of his canvas tent encampment along the riverbank. It was also fascinating to read his detailed descriptions of the local topography, still largely unchanged today–and to know that I was standing in the exact spot he once stood and literally following in his footsteps.
Next I found land patents signed by U.S. Presidents Grover Cleveland, William Taft and Theodore Roosevelt for the land on which the cemetery is situated. However, aside from a handful of deeds for small portions of the cemetery it is not clear how the City of Pocatello obtained ownership from the original patentees. I was surprised that the City has no written documents or deeds asserting ownership except for the Cemetery plat itself, which does not have an owner’s certificate.
I obtained current deeds for all adjoining properties and sketched them in AutoCAD together with the hundred year-old cemetery plats to ensure that everything fit. With consideration given for the limitations in measuring of the past (nearest minute and nearest tenth) everything fit together very well without any gaps or overlaps.
With a thick folder of historic documents and the 1922 "First Addition to Mountain View Cemetery" plat in-hand, it was time to begin the fieldwork. Several called-out government corners were quickly located. A center 1/4 corner was located inside the cemetery itself as referenced on the Corner Record, with ties from several named headstones. The corner consisted of the original stone monument from the 1889 Rhoades Townsite survey, with a 3" county brass cap alongside. I received many odd looks while digging with a shovel in the cemetery, but it was worth it. The government corners helped me to "get on the plat" and begin the hunt for cemetery boundary monuments and interior block corners. Using RTK-GPS and a pin sniffer, the interior corners were also relatively easy to find. Amazingly many of the original corners from 1922 still exist, protected under several tenths of soil. The corners were mostly uncapped 1/2" iron pipe and closely fit the record measurements. From the found block corners I calculated and temporarily staked out the specific lots of the memorial chapel grounds. The lot corners appeared to fit very well with existing streets, drainage ditches, tree lines, headstones and the chapel itself.
One of the lessons which I learned is that I collected far more records and observed more corner positions than I was able to use for any meaningful purpose; many more than those detailed in this article. If this had been a paying job I would have blown the estimate several times over, but since it was an educational project which I was personally interested in I did not mind investing extra time and effort. With the satisfaction that my boundary survey was accurate and complete, I was ready to tackle the laser scan of the chapel building.
I came across an online video demonstrating the awesome capabilities of laser scanning; collecting millions of points in a matter of minutes, creating a highly accurate 3D point cloud version of a physical entity and being able to manipulate and extract all kinds of data back in the office. In the video example a huge Bavarian castle was entirely mapped out within just a few hours. I knew I had to try laser scanning for myself.
The University did not have a scanner which was up to the task; no student had attempted a scanning project before. A local equipment supplier graciously loaned a Leica C10 and some instruction for the day. Control points were set in advance around the chapel using GPS which were then occupied by tripods with paddle targets during the scan. First year students were invited to come down and received a firsthand lesson in the laser scanning process. The chapel was scanned from five exterior locations and one interior scan. We scanned on the medium resolution setting, which at our average distance of 30′ creates a point spacing of approximately 0.03′. With the C10’s ability to collect a very impressive 50,000 points per second and working at a leisurely pace with frequent breaks for questions the entire chapel scan took about 4 hours.
The six individual scans were then registered together into a single point cloud using Cyclone, Leica’s proprietary point cloud software. The resulting point cloud contained approximately 60 million points (3.1 g
igabytes). Using the software I was able to fly around the scene in full 3D and view it from all angles. Every point within the cloud has a known 3D coordinate and accurate measurements can be made between any two points.
Back in the classroom using Cyclone I was able to extract the information I needed to create the deliverable products. One of the biggest challenges was my unfamiliarity with the software. I simply had to sit down and put in the time to figure it out. Once the basic commands were understood the process was easy enough.
I created a down-looking overview as-built map of the entire chapel grounds showing adjacent streets, drainage ditches, walkways, trees, benches, headstones and the chapel footprint–all fully dimensioned from the scan data. If I later wanted to show additional features another trip to the field would not be necessary–all of the data already exists and would only need to be extracted from the cloud.
I then re-made the first map by removing most of the labeled dimensions to clear up the clutter and under laid a color-coded DTM beneath the physical features. General elevation trends are easily seen at a glance; drainage patterns, high and low areas and spot elevations. Since my point cloud was so dense I actually had to thin out the data for my computer to calculate the triangles of the DTM without crashing. The data can be thinned out to make a grid of any desired spacing.
Next, using the point cloud I cut a thin horizontal slice through the chapel building. When viewed by itself the horizontal slice revealed the highly detailed chapel building footprint and wall thicknesses. Full dimensions and angles between features were easily added with a few mouse clicks.
And finally I created architectural-type elevation drawings of the front, sides and rear of the chapel. I ran images of the chapel through a filter in Photoshop to give them a hand-sketched pencil look as if they had just leapt from the architect’s desk. Dimensions and angles of the many intricate features were accurately superimposed over each image.
The potential real-world applications for this type of laser scanning are numerous. When a historic building needs restoration it may be important to create an as-built model before construction begins to ensure that the restored building accurately matches its original design. Or perhaps a complicated section of the building which would traditionally be difficult or tedious to measure, for example an outset Gothic archway, needs to be replaced and must be constructed at a specialty shop three states away. With 3D laser scanning data the arch could be constructed with the confidence it will fit upon delivery. New possibilities are created for those with the courage to try new things.
After four months of research, fieldwork, office calculations and the production of several survey drawings it was time to present everything to the panel of surveyors for my grade. Of course, I was nervous but I knew that I had given the project my best effort and felt well prepared. The 45 minute presentation went smoothly and many compliments were received. Although learning is eternal and must never cease, as I spoke the final words of my presentation and returned to my seat it was a great feeling to officially be a student no longer. The time had finally arrived to trade the classroom for paid employment on a real survey crew and all of the adventures which follow.
For the instructors my project brought to light the power and potential of laser scanning; which is now being incorporated into the program curriculum. The same company which loaned the Leica C10 scanner for my project is now loaning it to the Geomatics program for an annual demonstration. Students are able to scan objects around campus and practice manipulating the data with the software. This exposure to laser scanning technology gives both the students and the surveying industry an edge, as many companies are now looking to adopt the technology and are in need of qualified operators. Embracing the technology of the future will help to assure your place within it. Note: Photography and maps by the author.
Kevin McGuire is a recent graduate of Idaho State University’s Geomatics four-year degree program and holds LSIT and CST Level III certifications. He works on a wide variety of projects for his employer, Glahe & Associates, Inc., in beautiful north Idaho.
A 5.132Mb PDF of this article as it appeared in the magazineâ€”complete with imagesâ€”is available by clicking HERE