J.Hofierka, A.Petrasova, V. Petras, B.Harmon, P.Tabrizian, J.Jeziorska
Terrain as continuous field z=f(x,y),
represented by isolines, manually deriving secondary fields
Profle Curvature isolines (Krcho 1973),
Spatial interpolation by Regularized Spline with Tension (RST) method: from scattered points to regular grids, with simultaneous derivation of topographic parameters
Profle Curvature draped over mesh surface, (Mitasova, Mitas, Hofierka 1993)
Method became available to broad community, many developers improved the code
Surface with changing tension animation: tension helps to control overshoots
25 years: GRASS4.1 s.surf.tps, v.surf.tps, v.surf.rst; GRASS7.4; contributions of 8+ developers
Quadtree-based segmentation made it applicable to large point data sets
Simultaneous topographic analysis: slope, aspect, curvatures
Do we still need interpolation?
Jockey's Ridge 1974 - 2017: southward migration, landform transformation
from crescentic dune to sand starved, fast moving parabolic dune
Orthphoto from UAS survey, october 2016
Satellite imagery at 3m resolution, September 2017 - July 2018, captures impact of storm in March 2018 with large ripples similar to those observed post Mathews
Planet: world’s largest constellation of Earth-imaging (micro) satellites providing daily observations for entire Earth at 3m resolution
DEM time series is converted into space-time voxel model in TGRASS and evolution of a contour is represented as isosurface: 16m and 20m
DEM time series: evolution quantified using TGRASS and surface analysis tools
The 43 m high dune was a transient landform
Dune in early 1900 and in 2008, 2016
Land surface controls water and sediment flow across landscapes
Critical processes and impacts: surface runoff, flooding, storm surge, soil erosion
Using surface gradients to compute flow accumulation: Evolution of water depth over complex terrain under steady rainfall and uniform surface conditions
Geometry-based solution
Combining flow accumulation and slope:
Evolution of sediment transport capacity
Geometry-based solution
Net erosion and deposition computed as change in sediment transport capacity:
simple to compute in GIS, combined with parameters for landcover and soils
Unit Stream Power Based Erosion-Deposition,
Mitasova, H., J. Hofierka, M. Zlocha, L.R. Iverson, 1996
Next step: robust solution of shallow water flow equations and process-based sediment transport
Solver based on duality of particles and fields works for noisy surfaces, captures ponding in depressions.
Mitas and Mitasova, 1998; Mitasova, Thaxton, Hofierka, McLaughlin, Moore, Mitas, 2005
Impact of construction on erosion and deposition, limitations of stream buffer protection
Street level modeling of surface runoff: lidar-based DEM and path sampling
UAS-based surveys: cm-resolution DEMs
Path sampling simulations capture impact of microtopography: tillage
UAS-based surveys: efficient updates of urban topography
2015 lidar updated with 2018 UAS data: forested area replaced by a new school
2015 lidar updated with 2018 UAS data for area on Centennial Campus where two new buildings were built, trees cut and stormwater control is being updated
2015 lidar, UAS-based DSM is inserted, tilt identified and corrected
3D model of area with new buildings and removed trees
Payam Tabrizian PhD research project
Payam Tabrizian PhD research project
Viewshed based on bare ground DEM, lidar DSM, and modeled trunks
Petras, V., D. J. Newcomb, and H. Mitasova. 2017. Generalized 3D fragmentation index derived from lidar point clouds. In: Open Geospatial Data, Software and Standards 2(9). DOI 10.1186/s40965-017-0021-8
Bringing people together around GIS: Tangible user interface for GRASS GIS
Designed to make working with geospatial data and simulations engaging, and fun
Petrasova, A. et al. (2018). Tangible Modeling with Open Source GIS. Second edition. Springer International Publishing. https://doi.org/10.1007/978-3-319-89303-7
Tangible Landscape couples a digital and a physical model through a continuous cycle of 3D scanning, geospatial modeling, and projection
Tangible Landscape website:
tangible-landscape.github.io
TL wiki: github.com/tangible-landscape/grass-tangible-landscape/wiki
Developing open source software and contributing to OSGeo projects:
GRASS GIS https://grass.osgeo.org/
Tangible Landscape tangible-landscape.github.io
Open access educational material:
NCSU GeoForAll Lab Courses and Workshops https://geospatial.ncsu.edu/geoforall/courses.html
Thank you all for your contributions to the field - data, methods, algorithms and tools, that helped to bring the discipline to its current thriving state
discuss future: data for erosion to captiure the dynamics like for JR to improve the models, high accuracy is needed higher intensity rainfalls lead to increased erosion renewing interest in erosion and sediment contriol