Printing:Feasibility of Drone Use in 3D Geologic Mapping

Dan Bochicchio WCU Geoscience M.S. (BochicchioDM@Gmail.com), Dr. LeeAnn Srogi WCU Geoscience Professor (lsrogi@wcupa.edu)

Introduction

The development of microcontroller technology and image processing software in the past decade has led to thepivotal immergence of drone technology or Unmanned Aerial Vehicles (UAV). UAVs can produce orthophotosand DSMs at a fraction of the cost of manned aircraft and at a higher resolution than is currently available fromsatellite [1]. The Rock of Ages Quarry in Elverson, PA is a diabase monument and countertop quarry. Theproduct of this quarry is a series of sill deposits which exhibit fractional crystallization. Light colored plagioclaserich crystals have a high contrast to the dark colored gabbro which makes the distinguishing and eye-catchingpattern highly valuable. By taking pictures of the vertically cut quarry walls from several different angles, a 3Dmodel can be generated using photogrammetry software. That model can then be used to extrapolate thegeologic features within the rock. The quarry managers find this information very valuable in their operations toseek out the highest payout to waste rock ratio.

Methodology

Results

These 3D surface models can serve as a base for high-resolution surface mapping that will allow construction of anew generation of 3D geologic models at scales ranging fromhand specimen to tens of kilometers [3]. The advantages anddisadvantages of each software elude to an ambiguousconclusion: Depending on the required model detail, softwarebudget, and processing time allotted there is no perfectsolution. But, the highest recommendation can be given toDrone Deploy for it’s variety of features and ease of use.In comparison, each software has it’s intended purposes.Drone2Map integrates well with ESRI ArcMap and canprovide quick and easy dimensional reports designed for aclient. AGI Soft is more intended for the advanced user whowants more applications with the highest detail possible.Drone Deploy simply offers a service that can fit a broadrange of users and applications. Drone Deploys most uniquefeature is the cloud processing feature, which frees the usersresources for other work. The users time and effort is often themost valuable asset to a company and Drone Deploy canexport quality maps for geologic investigations.

AcknowledgementsThanks to Dr. LeeAnn Srogi for gaining access to the Rock of Ages quarry in Elverson, PA and ROA for allowing us to access their site for the study.As well as, Tim Lutz, Mike Cohen, Garrett Rees, and David Kodokian for assisting in the field work on September 15th and October 7th.

Works Cited[1] Harvey, M.C., Pearson, S., Alexander, K.B., Rowland, J. & White, P. (2014). Unmanned aerial vehicles (UAV) for cost effective aerial orthophotos and digital surface models (DSMs). New Zealand Geothermal Workshop

2014 Proceedings (in press), Auckland, New Zealand. Auckland, New Zealand.

[2] Li, Z., Zhu, C., & Gold, C. (2010). Digital terrain modeling: principles and methodology. CRC press.

[3] Siebert, & Teizer. (2014). Mobile 3D mapping for surveying earthwork projects using an Unmanned Aerial Vehicle (UAV) system. Automation in Construction, 41, 1-14.

Drone/UAV and CameraPhotogrammetric surveys of the quarry are conducted using a DJIInspire 1 Pro UAV. Images were captured with a 3-axis gimblemounted Zenmuse X3 camera (12 megapixel, 4096 x 2160 (4K)resolution, JPEG format). The flight paths were both automated andmanual. Automated top-down surveys were conducted using theDrone Deploy mobile application. Manual flights captured the detail ofthe walls and required a 3 person team – a pilot, a camera operator,and a visual observer who gives an adjacent perspective of the dronesposition relative the wall. Photos were taken in a grid that maximizedbattery life and captured the targeted geologic feature from severalangles which is ideal for photogrammetric modeling [2].

Keywords: Drone, UAV, Geologic Survey, Quarry, Diabase, 3D Modeling

PhotogrammetryModels were generated using 3 photogrammetry programs:Drone2Map, Drone Deploy, and AGI Soft Photoscan. Each operates ona similar photogrammetry model which uses overlapping photos todetermine the orientation of a 2D image in 3D space. By overlappingand orienting hundreds of photos, a point cloud is generated whichthen can be filled between each point to create the final 3D model.3D modelEach program has a unique approach to providing data visualization. Inregards to complexity and flexibility, AGI is the most robust tool allowingfor a broad range of outputs. Drone2Map highlights the simplicity ofmapping, but quality is not it’s strongpoint as seen in Figure 3. DroneDeploy takes from both and has the added advantage of cloudprocessing, eliminating hardware restrictions.

Figure 1. Orthomosaics (top) and DEMs (bottom) generated by Drone2Map (left), Drone Deploy (middle), and AGISoft (right). This demonstrates the varying accuracy and detail that different survey programs can provide based on the targeted value.

Figure 2. Screen captures of the same NW corner within a 3D model using:Drone2Map (A), Drone Deploy (B), and AGI Soft (C). The relative quality of each model can be compared which highlights the importance of scalable detail when identifying geologic features in 3D.

Figure 3. Oblique view of quarry in Drone2Map.

Figure 4. Hypothetical Cost vs Quality graph illustrating the relative relationship between each modeling software and the required minimum quality for geologic mapping.

A B

C

Drone2Map

Drone Deploy

AGI Soft

- Model Quality +

$$$

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