ES 775 Lab 5

ES 775 Lab 5
GROUND TRUTH
Cheyenne Bottoms, Kansas
James S. Aber

In this exercise, you will work once again with Ikonos imagery from the Nature Conservancy portion of Cheyenne Bottoms, Kansas--see exercise 3. As part of long-term enviromental monitoring, small-format aerial photographs have been taken during the growing seasons (spring, summer, autumn) over a period of several years. The goals of this enterprise are to establish ground truth concerning wetland conditions and to evaluate the effects of Nature Conservancy management practices. The kite and blimp airphotos were acquired from heights of 100-150 m above the ground mostly in oblique views.

Remote sensing research at Cheyenne Bottoms.

Idrisi Andes has a new photo layer capability for linking ground-truth photographs to base maps or images. See Idrisi Tutorial, part 1-7, p. 37. Read about photo layer in the Idrisi Help section on digitizing. The objective of this exercise is to create photo layers using an Ikonos panchromatic image as the base.

Exercise

Download the file CB_PAN_WIND into your student working folder. This file is derived from the same Ikonos multispectral dataset that you used in exercise 3. The original panchromatic band had 1 meter resolution. The image dataset was windowed to the specific study area of Nature Conservancy marshes, and cell resolution was contracted to 2 meters to reduce file size. Note: even with these reduction steps, the RST file is still almost 5 MB.

Examine the metadata for details. Now display CB_PAN_WIND with the grey palette, no title, and no legend. Hit the "end" key to maximize the display window. You can also "zoom" and move about the image to view details.

1. What parts of the spectrum are included in the pan band?

2. What are the smallest objects or features that you can visually identify in this image?

There are only a few ways to improve the appearance of a single-band, gray-tone image, such as this, namely with the STRETCH module (4th icon from left). Experiment with various stretch options to enhance this panchromatic image. Save your prefered version as the base image for the photo layer.

3. How did you create the enhanced base image?

For the photo layer, four sites are selected for display of small-format aerial photography. The locations and descriptions of these sites are given in the figure below.

Sample Ikonos panchromatic image of Nature Conservancy land in Cheyenne Bottoms. Click on small image to see larger version.
Kansas highway 4 runs across the top of the scene along with a railroad. Site 1 = Nature Conservancy barn and shop. Sites 2 and 3 = public nature trail to view marshes; these two sites have been utilized annually for SFAP. Site 4 = artificial drainage ditch.

SFAP images are selected to represent dry (drought) and wet (flood) conditions. Individual SFAP images are identified and described in the following tables. The approximate view direction (azimuth) is given for each oblique image.

**Site 1: Wet phase, August 2004**
Name	Azimuth	Features
CB05	320°	NC barn and shop next to Shop Creek. Blood Creek right background; Hoisington sewage treatment plant left background.
CB06	270°	Shop Creek on right side. Wet meadows.
CB07	135°	Shop Creek in foreground; wet meadows. Blood Creek in left background. CBWA in far background.
CB08	45°	Blood Creek across scene center. NC marshes beyond Blood Creek.

**Site 2: Dry phase, October 2006**
Name	Azimuth	Features
CB09	360°	Dry mudflats have been plowed (disked). Tractor is mowing vegetation thatch.
CB10	315°	Dry mudflats and meadows. Kite flyers at bottom of view. Hoisington in far background.
CB11	135°	Dry meadows in foreground. CBWA in far background.
CB12	50°	Dry mudflats and meadows. Site 3 at end of nature trail.

**Site 2: Wet phase, May 2005**
Name	Azimuth	Features
CB13	90°	Full marsh pools and wet meadows. Site 3 at end of nature trail.
CB14	315°	Muddy water in marsh pool. Hoisington in far background.
CB15	270°	Emergent vegetation in full-pool marsh. Cattle grazing in wet meadow.

**Site 3: Dry phase, May 2006**
Name	Azimuth	Features
CB20	45°	Dry mudflats and meadows. Delta of Deception Creek above scene center.
CB21	300°	Dry mudflats and meadows. Hoisington in far background.
CB22	225°	Dry mudflats and meadows. Blood Creek in background. Site 2 at fork in road.
CB23	140°	Dry mudflats and meadows. CBWA in far background.

**Site 3: Wet phase, May 2007**
Name	Azimuth	Features
CB16	90°	Flooded pools and meadows. Kite flyers at right edge.
CB17	45°	Flooded pools and meadows. Delta of Deception Creek upper center.
CB18	300°	Flooded pools and meadows. Hoisington in far background.
CB19	270°	Flooded pools and meadows. Blood Creek in left background. Site 2 at left edge of scene.

**Site 4: Dry phase, May 2004**
Name	Azimuth	Features
CB01	360°	Plunge pool at head of drainage ditch. Dry marsh with "weeds" scene center.
CB02	315°	Dry meadows and marshes. Hoisington in far left background.
CB03	240°	Dry meadows and cattle.
CB04	180°	Drainage ditch crosses section road. Dry meadows.

Download the SFAP images via FTP into your project working folder. You are now ready to create photo text layers using on-screen digitizing. Read and follow procedures in the Idrisi Help section on digitizing photo layers. Note in particular the procedure for editing or changing existing photo-layer vector files.

You will make two photo text layers--one for dry conditions (sites 2,3,4) and the other for wet conditions (sites 1,2,3). For sites 2 and 3, you may digitize the same points for each layer.

In order to activate the photo layer function, click "Feature Properties" button in the Composer window. Now move the cursor to a text label and click to show the associated SFAP images. Examine the SFAP images displayed using each photo layer.

Notes: You can display only one photo layer at a time on the base image. You must "remove" one photo layer before you can "add" the other. Some SFAP images may appear off the screen; move the base image to one side. Also some of the SFAP images may overlap each other; click on one and move it away.

4. Based on SFAP imagery, describe the appearance of Cheyenne Bottoms under dry conditions. Take note especially of water, vegetation, and soil moisture conditions.

5. Based on SFAP imagery, describe the appearance of Cheyenne Bottoms under wet conditions. Take note especially of water, vegetation, and soil moisture conditions.

Now compare the SFAP images with the panchromatic Ikonos image. In addition, compare these images with the multispectral composites and other images you made in exercise 3 for the same vicinity in Cheyenne Bottoms. The Ikonos dataset was acquired in July 2003 and represents typical low-water conditions in which small pools of water occupy marshes, mudflats are partly moist, and stream channels also contain water. In other words, the Ikonos images depict conditions in between completely dry (drought) and full pools (flood).

Many types of land cover are represented in the SFAP and Ikonos imagery: clean water, muddy water, moist mudflat, dry mudflat, emergent wetland vegetation, wet meadow, dry meadow, etc. The images depict these types of land cover in complicated mosaic patterns that change through time.

6. How effective is the Ikonos dataset for displaying, classifying, and interpreting different kinds of land cover at Cheyenne Bottoms? Explain your answer.

7. How could the effectiveness of Ikonos, Landsat, or other types of satellite imagery be increased for land-cover classification at Cheyenne Bottoms?

8. Explain the usefulness of SFAP for interpreting satellite imagery of land-cover conditions at Cheyenne Bottoms.

As your final task, create a map composition including the Ikonos panchromatic image and one of the photo text layers. Add a suitable title, subtitle with your name and date, and scale bar. Save an image file (jpg) to turn in.

Turn in

Written answers (1-8).
Digital file for your final map composition.