OpenTopography Usage Tutorials
Creating a digital elevation model and topographic hillshade:
We show how to make a digital elevation model (DEM) and how to create create a KMZ to display the hillshade on Google Earth or other GIS programs.
Accessing USGS 3DEP data on OpenTopography:
Learn how to access the USGS 3DEP dataset on OpenTopography. Currently, this service is limited to US academics but others can indicate interest in accessing this dataset after creating a free OpenTopography account.
Accessing global topography data:
In this video, we show how to access global data from OpenTopography including ALOS World 3D, Shuttle Radar Topography Mission (SRTM), and Global Multi-Resolution Topography (GMRT) datasets.
Canopy Height Model:
We demonstrate how to produce a canopy height model (CHM), also known as a normalized digital surface model, on-demand on OpenTopography. CHMs are calculated by subtracting the digital terrain model (DTM) from the digital surface model (DSM).
Watch this video tutorial to learn how to perform vertical change detection on OpenTopography's web interface. As of late 2020, vertical differencing is enabled on over 60 dataset pairs that capture a number of processes including urban growth, vegetation change, river processes, earthquakes and landslides.
Learn how to perform 3D differencing on OpenTopography's web interface. The 3D differencing tool uses the Iterative Closest Point algorithm to compute the best rigid deformation to register point clouds. This algorithm is best applied when the landscape shifts laterally such as in earthquakes, creeping landslides, and sand dune migration.
We discuss how to make a 3D print file (STL) from topography data using free and open source software including the DEMto3D plugin in QGIS and 3D Builder. We demonstrate how to select the size and resolution of the 3D print, how to apply a vertical exaggeration, and add a base to the 3D model.
Using the Potree point cloud viewer:
We demonstrate how to use the Potree point cloud viewer as part of our treasure hunt activity. Use the Potree viewer to visualize datasets by attribute such as classification, intensity or color, and to make measurements on the point cloud.
ArcMap and ArcScene Tutorials
Load DEM on ArcMap:
We show to 'connect to folder', load a DEM, and compute the statistics for the DEM.
Mosaic a DEM to a new raster in ArcMap:
We show how to mosaic several DEM tiles into an individual dataset which facilitates subsequent raster computations.
Add a color gradient to a hillshade in ArcMap:
We show how to improve our ability to visualize a digital elevation model by using a stretched color map for the DEM and adding a topographic hillshade.
Add a map layout, explanation, and export in ArcMap:
We show how to export a printable map as a PDF. We use the layout view to choose the area of the dataset that is being displayed and add a north arrow and a legend for the elevation.
Create DEM contours in ArcMap:
Learn how to make contour lines for a DEM.
Create a slope map and hillshade in ArcMap:
This video demonstrates how to make a slope map and slope shade which are powerful options for visualizing a landscape.
Use ArcMap's raster calculator for a Canopy Height Model:
We make a Canopy Height Model which computes the elevation of trees and buildings above the ground. This video describes how to use raster algebra and conditional statements to compute raster differences.
Compute watershed grids in ArcMap:
We use the hydrology tool box to compute watershed grids. We show how to perform fill, flow direction, and flow accumulation calculations in ArcMap.
Topography and drainage networks in ArcScene:
Use ArcScene to visualize topography in 3D and add a pre-calculated drainage network.
Measuring Strike and Dip:
We demonstrate how to measure geologic orientation from a point cloud using the Compass tool in CloudCompare. This video was developed for this structural geology exercise where students conduct a virtual structural analysis of the point cloud dataset at Painted Canyon adjacent to the Southern San Andreas Fault.
This tutorial demonstrates how to perform 3D differencing using CloudCompare. We apply this tool to synthetically offset datasets that represent a make-believe but realistic earthquake along the Wasatch fault in Salt Lake City. This video was developed as part of the Wasatch differencing exercise available here on OpenTopography and from NAGT/SERC .
In this video, we show how to visualize the snow-on and snow-off datasets at Reynolds Creek Critical Zone Observatory. We manually measure the difference in height between the two acquisitions. We perform a distance computation to measure the snow height over the entire dataset area.