Introductory Readings on Terrestrial Laser Scanning

I read two articles which gave me a more introductory look into terrestrial laser scanning (TLS) which detailed two different projects with goals behind them. The first, completed by Karagianni, detailed the use of TLS and used the project of capturing the façade of a historic house as the justification for advocating for TLS. The second project was a larger multi-disciplinary project spanning multiple organizations with the goal to capture the entire Cologne cathedral.

One thing that stood out to me was the wide use of software to achieve the desired results. This is reminiscent of my progress on my previous internship with photogrammetry under the direction of FPAN’s east central office, where I constantly switched to different slicing software for the best tool on a case by case bases. The cathedral project used Z+F LaserControl (v. 6.5), Adobe Photoshop, Leica Cyclone (v. 9.1), Autodesk ReCAP 360 (v.3.1), and ThinkBox Sequoia. All of these were used in the data-processing and visualization segment of the project. Likewise, Karagianni used Erdas Imagine, SCENE, and Pointools Edit. Both projects sought to capture buildings using the same methodology of TLS, but they used different software choices to achieve their results which is interesting that a wide range of software exists and is used for the same process. This make me question if there are certain software choices that bare a high cost, but are considered an industry standard amongst the field?

What is interesting is the limitations present in both works, distance is needed to get a good scan and tight close corridors or alleyways present a problem. Height is also a constant problem as these scanners are traditionally mounted on a tripod and take a few minutes to scan properly. The Karagianni project expressed this limitation and the Cologne cathedral project used scaffolding, extension arms, and the rooftops of nearby buildings to successfully capture most of the complex surfaces of the cathedral and overcome this limitation. This limitation will be present for my internship later on this summer and depending on the location, and scope of the scans, and we may need to explore ways to overcome this problem.

The results of these projects are impressive and scream for visualizations. These two projects helped me understand on how to use different forms of visualizations to make writing about these projects more effective which was something I struggled with in the past regarding my use of photogrammetry. Using a simple visualization like this flow chart helps the reader understand the process of the project in an easy to understand form. Below is screen capture of the flow chart presenting the process of Karagianni’s project.

 

 

The Cologne cathedral project used pictures to help visualize the how regarding the way the limitation of height was overcome to help the reader better understand that project. Below is a screen capture of a few pictures on how they were to visualize their success in overcoming the limitation they encountered.

While the end product of these laser scans, much like photogrammetry, produce eye catching data, visualizations regarding other aspects of these projects are important for contextualizing the process.

 

Karagianni, Aikaterini. “Terrestrial Laser Scanning in Building Documentation.” Civil Engineering and Architecture 5, no. 6 (2017): 215-221.

Pritchard, D., J. Sperner, S. Hoepner, R. Tenschert. “Terrestrial Laser Scanning for Heritage Conservation: The Cologne Cathedral Documentation Project.” ISPRS Annals of the Photogrammetry 4, no. 2 (2017) 213-220