Brendan Harmon

TanGeoMS: Tangible Geospatial Modeling System

We present TanGeoMS, a tangible geospatial modeling visualization system that couples a laser scanner, projector, and a flexible physical three-dimensional model with a standard geospatial information system (GIS) to create a tangible user interface for terrain data. TanGeoMS projects an image of real-world data onto a physical terrain model. Users can alter the topography of the model by modifying the clay surface or placing additional objects on the surface. The modified model is captured by an overhead laser scanner then imported into a GIS for analysis and simulation of real-world processes. The results are projected back onto the surface of the model providing feedback on the impact of the modifications on terrain parameters and simulated processes. Interaction with a physical model is highly intuitive, allowing users to base initial design decisions on geospatial data, test the impact of these decisions in GIS simulations, and use the feedback to improve their design. We demonstrate the system on three applications: investigating runoff management within a watershed, assessing the impact of storm surge on barrier islands, and exploring landscape rehabilitation in military training areas.

Tangible Modeling with Open Source GIS

This book presents a new type of modeling environment where users interact with geospatial simulations using 3D physical models of studied landscapes. Multiple users can alter the physical model by hand during scanning, thereby providing input for simulation of geophysical processes in this setting. The authors have developed innovative techniques and software that couple this hardware with open source GRASS GIS, making the system instantly applicable to a wide range of modeling and design problems. Since no other literature on this topic is available, this Book fills a gap for this new technology that continues to grow. Tangible Modeling with Open Source GIS will appeal to advanced-level students studying geospatial science, computer science and earth science such as landscape architecture and natural resources. It will also benefit researchers and professionals working in geospatial modeling applications, computer graphics, hazard risk management, hydrology, solar energy, coastal and fluvial flooding, fire spread, landscape, park design and computer games.

Beyond geomorphosites: trade-offs, optimization, and networking in heritage landscapes

This study uses Danxiashan, a world heritage site in Guangdong province, China, as a case study for planning a hypothetical geotourism network of heritage sites. This landscape has a multiplicity of values—its geoheritage cannot be separated from its ecological or cultural heritage. When designing a network of heritage sites for such a diversely valued landscape trade-offs must be made between differing and potentially conflicting objectives such as geotourism and geoconservation. To solve this multi-criteria decision problem, sites with potential value for people were designated as heritage sites, adapting the concept of geomorphosites—i.e., geomorphological heritage sites—to represent the intersection of anthropic values. In a GIS-based spatial decision support system heritage values for each site were weighted and ranked using the analytic hierarchy process and scenarios for alternative trail systems, and networks of tourism sites were generated by multi-criteria map overlay analysis and networking algorithms. The scenarios generated show how trade-offs can be made between oft-conflicting tourism and conservation objectives, how the design of parks can be optimized for multiple objectives, and how alternative design strategies can be explored. Such an approach could be used in scenario planning workshops to engage stakeholders in participatory design and consensus-based decision-making driven by geospatial science.

Immersive tangible geospatial modeling

Tangible Landscape is a tangible interface for geographic information systems (GIS). It interactively couples physical and digital models of a landscape so that users can intuitively explore, model, and analyze geospatial data in a collaborative environment. Conceptually Tangible Landscape lets users hold a GIS in their hands so that they can feel the shape of the topography, naturally sculpt new landforms, and interact with simulations like water flow. Since it only affords a birds-eye view of the landscape, we coupled it with an immersive virtual environment so that users can virtually walk around the modeled landscape and visualize it at a human-scale. Now as users shape topography, draw trees, define viewpoints, or route a walkthrough, they can see the results on the projection-augmented model, rendered on a display, or rendered on a head-mounted display. In this paper we present the Tangible Landscape Immersive Extension, describe its physical setup and software architecture, and demonstrate its features with a case study.

Evaluation of controls on silicate weathering in tropical mountainous rivers: Insights from the Isthmus of Panama

The Isthmus of Panama comprises a lithologically diverse andesitic oceanic arc of Late Cretaceous to Holocene age; it has large spatial variation in rainfall, displays a large range of physical erosion rates, and, therefore, is an ideal location to examine silicate weathering in the tropics. We use a multiyear data set of river chemistry for a 450 km transect across the Cordillera Central of west-central Panama to investigate controls on chemical weathering in tropical small mountainous rivers. Sea-salt corrected cation weathering yields (Casil + Mgsil + Na + K) range over more than an order in magnitude from 3.1 to 31.7 t/km2/yr, while silicate weathering yields (Casil + Mgsil + Na + K + Si) range from 6.9 to 69.5 t/km2/yr. Watershed lithology is the primary control on riverine chemistry, but landscape topographic character and land cover and/or land use also influence solute delivery potential. Strong statistical links of small mountainous river chemical weathering fluxes with rainfall and physical weathering rates attest to the importance of runoff and erosion in maintaining elevated bedrock weathering rates. CO2 consumption ranges from 155 × 103 mol/km2/yr to 1566 × 103 mol/km2/yr, in the upper range of global rates, leading us to suggest that andesite terrains should be considered separately when calculating removal of CO2 from the atmosphere via silicate weathering.

Linking silicate weathering to riverine geochemistry—A case study from a mountainous tropical setting in west-central Panama

Chemical analyses from 71 watersheds across an ∼450 km transect in west-central Panama provide insight into controls on weathering and rates of chemical denudation and CO2 consumption across an igneous arc terrain in the tropics. Stream and river compositions across this region of Panama are generally dilute, having a total dissolved solute value = 118 ± 91 mg/L, with bicarbonate and silica being the predominant dissolved species. Solute, stable isotope, and radiogenic isotope compositions are consistent with dissolution of igneous rocks present in Panama by meteoric precipitation, with geochemical signatures of rivers largely acquired in their upstream regions. Comparison of a headwater basin with its entire watershed observed considerably more runoff production from the high-elevation upstream portion of the catchment than in its much more spatially extensive downstream region. Rock alteration profiles document that weathering proceeds primarily by dissolution of feldspar and pyroxene, with base cations effectively leached in the following sequence: Na > Ca > Mg > K. Control on water chemistry by bedrock lithology is indicated through a linking of elevated ([Na + K]/[Ca + Mg]) ratios in waters to a high proportion of catchment area silicic bedrock and low ratios to mafic bedrock. Sr-isotope ratios are dominated by basement-derived Sr, with only very minor, if any, contribution from other sources. Cation weathering of Casil + Mgsil + Na + K spans about an order in magnitude, from 3 to 32 tons/km2/yr. Strong positive correlations of chemical denudation and CO2 consumption are observed with precipitation, mean watershed elevation, extent of land surface forest cover, and physical erosion rate.

Surface Water Flow Modeling

The topography of the Earth’s surface controls the flow of water and mass over the landscape. Modifications to the surface geometry of the land redirect water and mass flows influencing ecosystems, crop growth, the built environment, and many other phenomena dependent on water. We used Tangible Landscape to explore the relationship between overland flow patterns and landscape topography by manually changing the landscape model, while getting near real-time feedback about changing flow patterns. We coupled Tangible Landscape with a sophisticated dam breach model to investigate flood scenarios after a dam breach.

Real-Time 3D Rendering and Immersion

People’s perception and experience of landscape plays a critical role in the social construction of these spaces—in how individuals and societies understand, value, and use landscapes. Perception and experience should, therefore, be an integral part of environmental modeling and geodesign. With the natural interaction afforded by Tangible Landscape and the realistic representations afforded by Immersive Virtual Environments (IVEs) experts and non-experts can collaboratively model landscapes and explore the environmental and experiential impacts of “what if” scenarios. We have paired GRASS GIS with Blender, a state-of-the-art 3D modeling and rendering program, to allow real-time 3D rendering and immersion. As users manipulate a tangible model with topography and objects, geospatial analyses and simulations are projected onto the tangible model and perspective views are realistically rendered on monitors and head-mounted displays (HMDs) in near real-time. Users can visualize in near real-time the changes they are making with either bird’s-eye views or perspective views from human vantage points. While geospatial data is typically visualized as maps, axonometric views, or bird’s-eye views, human-scale perspective views help us to understand how people would experience and perceive spaces within the landscape.

Soil Erosion Modeling

Overland water flow can detach exposed soil and transport it over large distances, leading to soil loss and sediment deposition across landscape. Soil erosion can be effectively controlled by modifying topography to reduce concentrated overland flow or by planting vegetation to reduce soil detachment and transport. We used Tangible Landscape to analyze distribution of soil erosion and deposition potential in a small watershed and to design conservation measures by changing topography and planting vegetation in vulnerable locations. We iteratively adjusted and optimized our design based on real-time feedback from erosion and deposition maps projected over the modified 3D model. This feedback helped us to evaluate the effectiveness of our designs and develop better solutions.

Tangible topographic modeling for landscape architects

We present Tangible Landscape—a technology for rapidly and intuitively designing landscapes informed by geospatial modeling, analysis, and simulation. It is a tangible interface powered by a geographic information system that gives three-dimensional spatial data an interactive, physical form so that users can naturally sense and shape it. Tangible Landscape couples a physical and a digital model of a landscape through a real-time cycle of physical manipulation, three-dimensional scanning, spatial computation, and projected feedback. Natural three-dimensional sketching and real-time analytical feedback should aid landscape architects in the design of high performance landscapes that account for physical and ecological processes. We conducted a series of studies to assess the effectiveness of tangible modeling for landscape architects. Landscape architecture students, academics, and professionals were given a series of fundamental landscape design tasks—topographic modeling, cut-and-fill analysis, and water flow modeling. We assessed their performance using qualitative and quantitative methods including interviews, raster statistics, morphometric analyses, and geospatial simulation. With tangible modeling, participants built more accurate models that better represented morphological features than they did with either digital or analog hand modeling. When tangibly modeling, they worked in a rapid, iterative process informed by real-time geospatial analytics and simulations. With the aid of real-time simulations, they were able to quickly understand and then manipulate how complex topography controls the flow of water.