ES 771 Ikonos Satellite Imagery

FORT LEAVENWORTH, KANSAS

Introduction

Ikonos was the first commercial earth-resources satellite launched in 1999. Other, similar high-resolution commercial satellites have followed since. Ikonos provides high-resolution multispectral imagery. Individual blue, green, red, and near-infrared bands have 4-meter resolution (linear cell size), and the panchromatic band (green+red+near-infrared) has 1-meter cell size. This spatial resolution rivals conventional aerial photography. Imagery may be ordered from a global archive, or users may specify acquisition for certain dates, locations and cloud-cover conditions.

Ikonos from Satellite Imaging.

For this exercise, you will work with multispectral data for Fort Leavenworth, Kansas. Fort Leavenworth is the oldest military base in the United States west of the Mississippi. It was founded in 1827 on the west side of the Missouri River, a few miles upstream from its junction with the Kansas (Kaw) River. This region had been the focus for exploration and temporary European trading posts since the mid-1700s, when the French established Fort de Cavagnial nearby. The region was acquired by the United States as part of the Louisiana Purchase in 1803, and Lewis and Clark visited the site in 1804 on their historic journey.

Today Fort Leavenworth is home to the U.S. Army's Command and General Staff College and the National Simulation Center. Military officers from all service branches receive advanced training in warfare tactics and battle simulation. Military officers are trained from many other countries around the world as well. The U.S. Disciplinary Barracks (prison) is also located at Ft. Leavenworth. The military reservation includes substantial forest, both in the Missouri valley bottomland and on upland bedrock ridges. The bottomland was inundated during the great flood of 1993.

Lewis and Clark bicentennial atlas.

Download Idrisi files for Ikonos multispectral bands: LV_BLUE, LV_GREEN, LV_RED AND LV_INFRARED. This dataset was acquired in August 2000 at the beginning of a drought period. Note: the RST files are ~3 MB in size each (the panchromatic image is 16 times larger).

Exercise

Open the metadata for one of the images. Examine information about the raster image.

1. Provide the following spatial details about the raster grid: number of rows and columns, linear size (resolution) for each cell, and total ground area (in kmē).

Now create two standard color composites: natural color (blue, green, red) and false-color (green, red, near-infrared). Use the color composite function (4th icon from left). Select the appropriate bands, and provide a suitable output file name and image title. Leave contrast stretch and output type in the default modes. Change percent to be saturated to 5. Your resulting images should appear similar to the following examples.

Natural-color (left) and false-color composite.

For each of the images, describe the appearance of the following features, paying attention to elements of image interpretation--color, size, shape, pattern, texture, shadows, etc. Hint: enlarge the image to see details for each of these features.

2. Airfield runway, hangers and other buildings (near scene center).

3. Missouri River. The large meander loop is called Weston Bend.

4. Forested zones, including bottomland forest within Weston Bend and the upland forest just west of the airfield.

5. Golf course (lower left portion of scene).

6. Based on these observations, what are the smallest features you can identify with certainty in the Ikonos multispectral images. Explain how you are able to identify these features. Note: be sure to zoom in to see details.

Now examine the vegetation features in more detail. The forested portions of Fort Leavenworth are among the best of their types--both upland and bottomland--preserved in northeastern Kansas. Prepare an NDVI image based on the red and near-infrared bands, as you did in the previous exercise.

7. What is the range of NDVI values displayed in this image? What do high values mean; what do low values indicate?

8. Describe each of the features noted above (#2-5) as they appear in the NDVI image.

9. Examine the forested regions in detail. Can you discern any differences between the upland and bottomland forests? Consider NDVI values as well as spatial patterns and textures. Hint: enlarge the image to see details for each of these forests.

The original keelboat (later steamboat) landing at Fort Leavenworth was located where the Missouri River flowed against the western side of its valley. This point is now dry land near the southern end of the present airfield runway.

10. Examine each of the images you have created. Can you identify any traces of the former Missouri River that existed at the time Fort Leavenworth was founded 180 years ago? Explain your answer.

Lewis and Clark keelboat reenactment.

Now use on-screen digitizing to create a vector file that traces the path of the former Missouri River that existed at the fort was founded. See digitizing icons near center of tool bar. Select the "digitize" tool. Enter a suitable file name and click "line" for layer type. Leave other options in default mode, and click OK. Now left click with the mouse along the line of the old river path. When you have finished, right click to end digitizing, then click the "save digitized data" on the tool bar. The path should appear as a cyan line.

The digitized line is thin and may not appear clearly depending on its color relative to adjacent feature colors. Under "Layer Properties," you can change the color and thickness of the line using the Advanced Palette/Symbol Selection options. Make your river path a bright red, Xwide line.

As your final task, prepare a map composition based on the NDVI image with the old river path vector layer. Your composition should have the following elements: suitable title, subtitle (your name and date), scale bar, and north arrow, but no legend. In addition, include a "text inset" with a brief explanation of the old Missouri River channel. Add an attractive, pale background color to complete the composition.

Note: the image scene of the composition should be completely visible; none of the other elements should overlap or obscure any part of the Ikonos image. Name your final composition LV_NDVI and save as a jpg file to turn in.

Turn in:

ES 771 schedule or ES 771 homepage.

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