Graduation Year

2017

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Bogdan P. Onac, Ph.D.

Co-Major Professor

Sarah Kruse, Ph.D.

Committee Member

Mel Rodgers, Ph.D.

Keywords

structure from motion, ground penetrating radar, photogrammetry, GIS, karst

Abstract

Scărişoara Ice Cave has been a catalyst of scientific intrigue and effort for over 150 years. These efforts have revealed and described countless natural phenomena – and in the process have made it one of the most studied caves in the world.

Of especial interest is the massive ice block located within its Great Hall and scientific reservations. The ice block, which is the oldest and largest known to exist in a cave, has been the focus of multiple surveying and mapping efforts, typically ones utilizing traditional equipment. In this study, the goals were to reconstruct the ice block/cave floor interface and to estimate the volume of the ice block. Once the models were constructed, we aimed to study the relationships between the cave and ice block morphologies.

In order to accomplish this goal, three (3) main datasets were collected, processed, and amalgamated. Ground penetrating radar data was used to discern the floor morphology below the ice block. Over 1,500 photographs were collected in the cave and used with Structure from Motion photogrammetry software to construct a texturized 3D model of the cave and ice surfaces. And a total station survey was performed to scale, georeference, and validate each model. Once georeferenced, the data was imported into an ArcGIS geodatabase for further analysis.

The methodology described within this study provides a powerful set of instructions for producing highly valuable scientific data, especially related to caves. Here, we describe in detail the novel tools and software used to validate, inspect, manipulate, and measure morphological information while immersed in a fully 3D experience.

With this methodology, it is possible to easily and inexpensively create digital elevation models of underground rooms and galleries, to measure the differences between surfaces, to create 3D models from the combination of surfaces, and to intimately inspect a subject area without actually being there.

At the culmination of these efforts, the partial ice block volume was estimated to be 118,000 m3 with an uncertainty of ± 9.5%. The volume computed herein is significantly larger than previously thought and the total volume is likely significantly larger, since certain portions were not modeled during this study. In addition, the morphology of ceiling enlargement was linked to areas of high elevation at the base of the ice block. A counterintuitive depression was recognized at the base of the Entrance Shaft. The thickest areas of the ice were identified for future coring projects. And combining all this a new informational allowed us to propose a new theory on the formation of the ice block and to decipher particular speleogenetic aspects.

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