Lab Five: Geovisualization and Pattern Discovery - Draping Geology and Cultural Features on Topography


Colo. Geological Survey geology Shapefile draped over USGS DEM of the Carbondale, Colo. area. Mt. Sopris (12,965 ft.) on left, Crystal River drainage on right.	USGS DRG draped over USGS DEM of same view as left image.

Lab Five goals:

to experience real-world applications of geovisualization (in our case, we are using map layers to visualize the relationship between topographic relief and other themes)
to work with different data models (DEMs, DRGs, Shapefiles) in a GIS project
to explore the concept of obtaining pixel elevations from DEM sources (a concept called 'draping')
to freely rotate and interact with surface models to locate patterns and relationships
to learn about and use 'extensions' in ArcGIS (extensions, such as the Spatial Analyst extension, allow users to perform specialized functions)

Tools:

ESRI ArcGIS ArcScene 9.3.1 Visualization Software
ESRI ArcGIS Spatial Analyst Extension
Adobe PhotoShop CS4
Adobe DreamWeaver CS4
SSH Secure Shell File Transfer
a web browser

Background:

In Lab Five, students work with ArcScene, an ESRI GIS software product designed for 3D data visualization. The user interface in ArcScene is similar to that of ArcMap, the software used in Lab Four. ArcScene provides an environment through which students visualize landscapes by overlaying thematic maps (geology, DRGs) over digital elevation models (DEMs). While gaining experience using tools for data visualization and pattern discovery, students explore the relationship between topographic relief and geology, topography, drainage systems, land use and land cover, and the built environment. The data used in Lab Five include Colorado Geological Survey geologic maps in Shapefile format and raster-based USGS DEMs and DRGs. Following work from Lab Four, students are expected to know how to add data, select layers, and turn on/off layer displays in an ArcGIS environment.

Lab overview:

Lab Five is divided into three parts. The first part involves creating two new folders under the 'lab_5' directory and copying directories from Brandon's faculty drive to student Z drives. The second part walks students through an ArcScene project in which geology vector polygon Shapefiles and raster DRGs are draped over raster DEMs. Also in the second part of Lab Five, students create and add contour lines to maps. The third part involves exploring and interacting with maps to identify patterns between topography (relief on the physical landscape) and other themes of choice. Map data used in Lab Five are free and are available for download from various government web sites. Lab Five data include 1) USGS DEMs (.tif format), 2) USGS DRGs (.tif format), and 3) Colorado Geological Survey Shapefiles (.shp format).

What I grade (READ THIS CAREFULLY):

1) Short Map Report narrative: In a well-written paragraph or two, students must first identify and then discuss the relationship between 1) topography (the DEM) and 2) a theme of choice such as geology, geomorphology, rivers/drainages, anthropogenic (Man-made) landscapes, land cover, land use, transportation, etc. In other words, in a short narrative, students should clearly and succinctly articulate how a region's topography is related to an identifiable geographic theme. SPEND SOME TIME ON THIS REPORT.

2) Three (3) mages; each with a caption:

one (1) image must show any interesting map view or perspective
two (2) images must illustrate and support your theme of choice (the images must support your short Map Report narrative)

Part One - Getting set up:

To stay organized throughout Lab Five, create two new directories (data and project) on your Z drive in your Lab Five folder:

/ges205/web/lab_5/data/ (use this new directory to store the folders/files that you copy from Brandon's faculty drive)
/ges205/web/lab_5/project/ (use this new directory to store the ArcScene project file)

Get your data (pick one set of four) from Brandon's faculty drive outbox:

1) Data paths for Mt. Sopris (near Carbondale, CO) (COPY THE ENTIRE mt_sopris_co directory):

a) DEM layer: OutBox/arcscene_data/mt_sopris_co/dem/sopris
b) DRG layer: OutBox/arcscene_data/mt_sopris_co/drg/o39107c2.tif
c) geology layer: OutBox/arcscene_data/mt_sopris_co/geology/geology.shp

2) Data paths for Durango East, CO (COPY THE ENTIRE durango_e directory):

a) DEM layer: OutBox/arcscene_data/durango_e_co/dem/durango_e
b) DRG layer: OutBox/arcscene_data/durango_e_co/drg/o37107c7.tif
c) geology layer:OutBox/arcscene_data/durango_e_co/geology/geology.shp

3) Data paths for Durango West, CO (COPY THE ENTIRE durango_w directory):

a) DEM layer: OutBox/arcscene_data/durango_w_co/dem/durango_w
b) DRG layer: OutBox/arcscene_data/durango_w_co/drg/o37107c8.tif
c) geology layer:OutBox/arcscene_data/durango_w_co/geology/geology.shp

4) Data paths for Gribbles Park (near Salida, CO) (COPY THE ENTIRE grib_prk_co directory):

a) DEM layer: OutBox/arcscene_data/grib_prk_co/dem/grib_prk
b) DRG layer: OutBox/arcscene_data/grib_prk_co/drg/o38105f7.tif
c) geology layer:OutBox/arcscene_data/grib_prk_co/geology/geo.shp

Part Two - Assembling layers in ArcScene:

Read about ArcScene here.
Open ArcScene: Go - All Programs > Geography > ArcGIS > ArcScene.
Turn on the Spatial Analyst extension: Go - Tools > Extensions (then check the Spatial Analyst box). Spatial Analyst supports the construction of contour lines, which you will create later in this lab.
Guys -- be patient. Some tasks in this lab are processor intensive and take some to time to render.
Start with locations 1,2,3, or 4 from above. Using the 'add data' icon, add to your ArcScene project the DRG, the DEM, and the Geology shapefile from your newly created ges205/web/lab_5/data directory (NOTE: There are multiple Shapefiles associated with the geology layer - just add the layer called 'geo' or 'geology').
After adding the DRG and the DEM to your project, you'll probably see a screen that asks if you want to build pyramids. Say yes.
When initially loaded, the geology Shapefiles will display one color for all rock types (shown as individual polygons). Change the layer properties of the Shapefile to show unique values for the field called "FMT" - these are the geologic unit names. To do this: Right-click on the geology layer; click the "symbology" tab; show "catagories", "unique values"; change value field to 'FMT'; then click the "Add All Values" button to display all of the geology polygons in the Shapefile. Lastly, select 'okay'.
We are ready to drape the geology and DRG layers over the DEM! Here's how you do this: Let's start with the geology layer - Right-click on the Geology shapefile in the table of contents and select the "Base Heights" tab. Click the "Obtain heights for layer from surface" and set the source to your DEM (e.g., grib_prk). Leave the "offset" as 0. Click okay.
Turn off the DEM and DRG layers displays so you view only the geology (which now should float above and conform to the DEM). Pretty cool, eh?
Use Arcscene's 'navigate' icon (the globe with the four arrows around it) to change your data view perspective. Remember: BE PATIENT when you move your displays!
Next, drape the DRG over the DEM. This time, drape the image 200 meters over the DEM (change the "Offset" to 200). This will stack your two layer separately on top of the DEM with a 200 meter buffer.
Next, using the View menu, select "3D Effects" from the toolbar dropdown list. You can use this tool to easily adjust the transparency and lighting of different layers. Experiment with this.
Next, make visible the Spatial Analyst toolbar. From this toolbar, add contour lines to your geology shapefile: Add contour lines to your DRG at a 50 interval relative to your DEM.
Right-click on the new Contour line layer's properties. Set the "Obtain heights for layer from surface" value to the DEM. You should now see contour lines conform to your geology map, not the DEM surface! COOOL!
Remember that you'll need to CAPTURE ONE IMAGE THAT SHOWS ANY INTERESTING VIEW - THIS MIGHT BE A GOOD TIME TO DO THAT!
Turn off your contour lines.
Save your ArcScene document (.sxd) to your newly created ges205/web/lab_5/project directory.

Part Three - Pattern discovery through geovisualization

This is the fun part. Explore. Surf you map layers. Adjust the zoom and use the 'navigate' icon to adjust, twist, turn, and move, your DRG and your geology layers. What do you see? What sort of general statement can you make about patterns and relationships between topography and any number of other themes or features? In other words, use your imagination a bit to seek out any sort of relationship between topography, themes on the DRG, or patterns on the geology layer. What do you see? How does topography control other themes found on your maps?
The goal here is to identify (and discuss in a paragraph or two) the relationship between 1) elevation/topography (your DEM) and 2) any other theme of choice such as rivers, geomorphology, Man-made landscapes, land cover, transportation, etc. Use TWO (or more) IMAGES/SCREEN CAPTURES to illustrate this relationship.


Durango West	Durango East