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Web viewers based on open source code, of the park without disrupting wildlife and Web-Based 3D Point Cloud (potree)
such as potree (Schuetz, 2016), use WebGL the natural landscape. Viewers using potree code can render raw
API to efficiently render massive point point clouds and integrate multiple data sets
clouds (>10 points) in standard Internet Data Collection and DOM into a single viewer with customizable
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browsers. Potree does not require end-users Processing options. The dense point cloud for the 1 km
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to install software or download large data Images were collected through eight field area is ~25.5 GB and contains more
sets (Schuetz, 2016) and has been adopted flights with a sensefly eBee fixed-wing UAV than 805 million points (Fig. 3B). Point cloud
by various organizations, including the equipped with a Sony WX220 18.2 mega- data sets can be compressed (from .las to .laz
USGS, for sharing and visualizing national pixel camera, resulting in 1760 images. format) to reduce file size and converted into
topographic LiDAR data sets (USGS, 2019). Images were recorded at a pitch angle of 10º a potree file and folder structure for efficient
Similarly, OpenTopography and Pix4D- off-nadir to increase point visibility along tile-based rendering using the potree con-
cloud provide online viewers, similar to sub-vertical surfaces and increase precision verter (Schuetz, 2016), with a final size of 3.5
potree, allowing subscribers to share point of final models within the high-relief topog- GB. By default, the potree code includes an
clouds through standard web browsers. raphy (Nesbit and Hugenholtz, 2019). Images interactive overview map that displays the
Alternative methods have incorporated were processed using Pix4Dmapper v4.3 fol- viewer’s location and view direction, various
the use of game engines to create custom- lowing a similar workflow described by pre- navigation options and settings, and several
ized geovisualizations compatible with vari- vious authors (Küng et al., 2012; Nesbit et al., measurement tools allowing end-users to
ous operating systems. Unity and Unreal 2018). Following initial processing, the record simple measurements, including
Engine are two popular game development model was divided into four quadrants and distances, areas, volumes, and topographic
platforms that are well-documented, have processed into a dense point cloud and 3D cross sections. Following conversion, the
vast online programming communities, and textured mesh. Mesh outputs were exported files and folder structure can be added to a
are available for free to developers producing as Autodesk Filmbox (.fbx) format, which web host and dispersed through a standard
revenue below a defined threshold. Recently, generally results in smaller file sizes than web domain. Information on getting started
game engines have been used in the geosci- commonly used 3D polygon (.ply) and wave- can be found on the potree GitHub page or
ences for the gamification and sharing of 3D front (.obj) formats. homepage (http://www.potree.org). An ex-
data sets in immersive virtual reality (VR) ample is presented in Figure 3B using the
(Bilke et al., 2014), translating ArcGIS data Visualization Approaches Pix4Dcloud viewer, which implements the
into a 3D environment using Unity (Robin- DOMs are presented in textured mesh and potree library.
son et al., 2015), and presenting virtual dense point cloud formats, using three
archaeological sites (Martinez-Rubi et al., different visualization platforms (Sketchfab, Videogame Engine (Unity)
2016; Boutsi et al., 2019). potree, and Unity). Although other platforms Videogame engines allow the production
are available, these were intentionally selected of unique end-user experiences through cus-
CASE STUDY: FLUVIAL for their ability to provide end-users with tomized data visualization and presentation
STRATIGRAPHY, DINOSAUR access to 3D data sets without specialty (Fig. 4). Unity provides a platform to design
PROVINCIAL PARK software or transfer of large data sets and are and develop videogames and is well docu-
representative of the current capabilities of mented through user manuals, community
Geological Overview modern viewers. forums, and online tutorials (e.g., https://
Dinosaur Provincial Park is a UNESCO unity.com/learn/get-started). The program
World Heritage Site in southeastern Alberta, Web-Based 3D Mesh (Sketchfab) interface contains simple “drag and drop”
Canada, recognized for an abundance of Using a web-based interface, Sketchfab functions for creation of simple scenes, but
well-preserved dinosaur fossils and charac- allows authors to intuitively upload models, also allows fully customizable objects and
teristic badland topography (Dodson, 1971; define rendering options (e.g., lighting, mate- interaction through scripting. Unity supports
Currie and Koppelhus, 2005). This case rial properties), and provide supplementary various formats, including point clouds,
study presents a 1 km subsection within annotations (Fig. 3A). Upload limitations of meshes, and 2.5D digital elevation models
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the northeastern portion of the park con- 200 MB, including all mesh and texture com- (DEMs). However, point cloud rendering
taining extensive 3D exposures of the ponents, prevented rendering of the complete through Unity can be challenging (Fraiss,
Late Cretaceous Dinosaur Park Formation 1 km field area within a single viewer without 2017), and DEM interpolations are suscepti-
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(Wood et al., 1988; Eberth and Hamblin, significant texture distortion. To preserve ble to distortion along slopes (Bellian et al.,
1993). Contrasting layers of siltstone and detail within the field area, we present each 2005; Pavlis and Mason, 2017). Therefore,
fine- to medium-grained sandstone along quadrant separately. Multiple texture resolu- we used 3D meshes (.fbx files) and associ-
with the stratigraphic architecture are rep- tions and VR compatibility are automatically ated textures (.jpg), which made up much of
resentative of successive meandering chan- generated during upload to provide end-users the final videogame file size (~1 GB).
nel belts cutting through adjacent flood- with different level of detail (LoD) rendering Navigation within the scene was pro-
plain mudstones (Figs. 1–2; Smith et al., options based on the capabilities of their view- grammed through a first-person movement
2009; Nesbit et al., 2018; Durkin et al., ing device. Location-specific annotations script, in which the camera is controlled by
2020). Most of the park is a natural preserve describing geologic features and concepts to directional keys on the keyboard and orien-
accessible only through research permits or end-users were added to models using the tation based on the mouse. Camera move-
guided programs. The digital model pro- upload interface. Additional data sets could ment was restricted within the scene bound-
vides a viewing window into a small section not be integrated within 3D model space. aries by enabling the “mesh collider” option

6 GSA Today | June 2020