During this lab you will work on building, displaying and
manipulating digital elevation models (DEMs). You will build on what you learned in last week's lab, but this time build your own DEMs from raw topographic survey data. The skills you develop are critical in terms of understanding how to convert raw vector data into interpolated surfaces from which additional spatial analyses can be done. Although we use elevation as the 3D data to build a surface from, these same skills apply to any type of spatial data you can interpolate (e.g. temperature, pressure, habitat quality, gravity, etc.).
- Worked with raw topographic data in common formats
- Built a high-resolution DEM from raw topographic survey data (ground-based)
- Built a high-resolution DEM from processed airborne LiDaR data (remotely-sensed)
- Run a simple change detection analysis on multiple year DEMs
Meets Course Learning Outcomes 2, 3 & 5.
As with all labs... This is a fictitious scenario!
You are still working for the environmental consulting firm (Big
Cheese Watershed Management) which specializes in watershed management. Your boss asked you to build some DEMs from raw data provided by a client for a new project in Oregon and he wants you to put together your figures and findings on a couple of
project pages (your lab pages). The pages will be used to illustrate
for the client the variety of DEM data available for their project and
to help them understand the differences between the data types.
His vague instructions and context can be summarized as follows:
Watershed Sciences, and is now publicly available on the Open Topography portal. Go download the raw bare earth point data and construct a DEM for the same reach to provide a little more landscape context and demonstrate the resolution differences between the raw survey data and Lidar."
- For Task 1:
- Set of informal figures illustrating
- the raw topographic survey data (i.e. points and breaklines) and
- the TIN,
- Descriptively caption figures for full credit
- Provide a figure that makes a formal comparison illustrating the differences between DEMs derived from the same TIN at different resolutions (e.g. 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, 1.0 m, ) (NOTE: choose a scale/extent that illustrates the differences at all resolutions - focus on a feature)
- Choose the most appropriate resolution at which to model this topography with a raster DEM. Justify your choice in a brief discussion about the resolution of the raw survey data and what you know about raster creation processes.
- Provide a figure displaying your final DEM (of resolution chosen for analysis) w/ water depth layer (include resolution in figure caption)
- Provide links to higher resolution JPG or PDFs if the
images on your webpage don't show relevant details.
- For Task 2:
- In a well marked section provide a brief explanation about the differences between the DEM created from raw survey data in Task 1 and the LiDAR DEM created in Task 2 with respect to channel change detection. What are the pros and cons of each? (Use additional figures to illustrate your points if necessary.) Specifically, with the goal of analyzing the surface to detect changes in channel morphometry, address whether the airborne LiDAR would be more or less effective than the survey DEM. Incorporate what you've learned about airborne LiDAR and the survey data, and think about data extent, resolution, and what types of features can or can't be resolved by each data set to support your decision to use one or the other for change detection analysis.
- For Task 3:
- Provide a figure that effectively displays the results of your change detection analysis
- include appropriate context (descriptive caption, scale, location)
- Use LiDAR DEM from Task 2 as your base layer.
- Provide a screenshot of your model with a caption that fully describes how the model works and what it does.
- Provide a link to download the DoD model/toolbox you created.
Make sure your lab conforms to the general lab submission guidelines. Submit a URL for this lab's webpage.
Lab 7 Slides - Shannon Belmont Spring 2013
- USGS National Map Seamless Server - Download various elevation datasets 10 m, 30 m and 90m for entire country
- USDA’sGeospatial Data Gateway - You can also download 10 m and 30 m DEMs from here (much easier to use then National Map Seamless Server)
- Open Topography Portal - This is primarily just high resolution LiDaR data, but very useful if it happens to fall within your study area.
- Utah GIS Portal Elevation Datasets - In Utah, we have access to a lot of great DEM datasets that other states do not!
- Columbia Habitat Monitoring Protocol - Has total station survey data for 100's of sample reaches similar to Task 1 throughout the Columbia Basin
- LiDaR Technology & Applications Course Page - This is a course web page for a LiDaR course taught at Penn State. It is an excellent resource of information to learn more about how LiDaR data is acquired and what can be done with it.
- Introduction to 3D Analyst Tutorials
- 3D Visualization Techniques Using ArcGIS 10 - This one isn't free.
- Using ArcGIS 9.3.X to Construct and Manipulate DEMS - Tutorial ; Data (Part of ICRRR Part II Short Course) - I prepared this for ArcGIS 9.3x and it is very similar to Task 1.
- Fundamentals of Surfaces- ESRI Help Document
- Building a TIN to represent a Terrain - ESRI Help Tutorial
- Creating and Using a Terrain Dataset - ESRI Help Tutorial