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University of Nebraska–Lincoln

You and your family have won an all-expense paid trip to see the season opening game of America's #1 football team, the Nebraska Cornhuskers. You arrive in Lincoln on Friday night and find a motel room close to the airport. Saturday is going to be a beautiful late summer day. You and the your family have to decide what you are going to do until game time at 7:00 pm.

What will it be: a visit to the State Capitol; a visit to the zoo; or a leisurely stroll through Pioneer park.

Not! Dad wants to go golfing at Mahoney Golf Course and you want to go to the State Fair and mom wants to shop at the Gateway shopping center. Unfortunately you only have one automobile, and Dad wants it. The question is, how far is it to the parking lots of Gateway, the beflagged greens of golf land and the State Fair park? Can you walk? Or are you going to trade a ride for washing dishes back home for the next month? How can you find out?

Fortunately, you have a high powered computer in your room (this is a very progressive hotel!), an imaging program, and an aerial image of Lincoln that shows your targets for the day! Let's use the measuring tools in the image program to measure the distances to your goals:

Opening an Image

First, open the imaging program, NIH Image, by clicking twice on the Image icon (a small microscope). Next load the Lincoln Landmarks image, named "LincLand", by selecting the File/Open option. (That is, click down on File on the top menu bar, drag down to Open on the pull-down menu which appears, and release. A dialog box will appear that you may use to locate and open the desired file.)

Note: If you get a message such as:

"This XXXK image is larger than the XXXK UNDO buffer. Many operations may fail or be Undoable."

Then:

  1. 1. Click OK.
    2. Select Options/Preferences.
    3. In the box labeled "Undo & Clipboard Buffer Size," type in a size larger than the size of the image you wish to open. For example, if the image size is 400K, then try making the buffer size 500K.
    4. Click OK.
    5. Click OK to the message: "You must close...."
    6. Quit NIH Image by selecting File/Quit.
    7. Restart NIH Image and try once again to open the image.

Using the Magnifying Tool

What a view! If you want to see something a little closer, select the magnification tool from the Tool Bar by clicking once on the little magnifying glass symbol. Your cursor will turn into a magnifying glass symbol. Move the symbol/cursor to any point on the image you want to see enlarged and click. Clicking again enlarges the image again. To shrink the image, hold down on the Option key on your keyboard and click. "You got da' power!" For this image, enlarging more than once is of little value because the pixels (square dots) that make up the image are so large (about 15 meters or 50 feet) compared to most houses and buildings. Features like buildings turn into a bunch of unrecognizable colored squares after just a few clicks on the mouse (try it!).

Setting the Scale and Using the Measuring Tool

Setting Scale

Now we need to set the scale on the image. Conveniently, there is a scale bar at the top of the image. First, click on the straight line measuring tool in the Tools Bar (fifth down, ). Move the cursor to the left end of the scale bar, click and drag the cursor to the other end (at 3 kilometers) and release. You should see a series of dashes moving along your measured line (the "marching ants"). Now select Analyze/Set Scale to get a dialog box. The length in pixels of the line you measured is shown in the box at the top. Select "kilometers" for the units and type the distance in kilometers in the Known Distance box (4.0 if you measured the whole line). The computed scale appears in the Scale box. Click OK to close the box. Now as you move the cursor around the image, the coordinates and any measurements you make will be in kilometers.

Making Measurements

To determine what measurements you make, select Analyze/Options to get a dialog box. All of the measurements with clicked boxes will be taken. For now, select only the Perimeter/Length (an "X" should appear in the box - all the other boxes should be empty), and click OK to close the dialog box. You are now ready to measure.

To find the distance from the Cornhusker Hotel to any spot on the image, move the cursor to the hotel, click and drag the cursor to the desired spot and release. Now select Analyze/Measure and then Analyze/Show Results to get your distance measurements.

These distances are straight "as the crow flies." They are not very realistic since you have to follow the streets to get from one place to another (unless, of course, you happen to be a Super Hero in disguise!). To get a more accurate distance, click and hold on the line measure symbol to get a dialog box. Select Freehand Line and release. Now when you click and drag on the image, the cursor will make a line along any path you choose, and not a straight line between the endpoints. Now starting at the hotel, trace along major roads to your target. Now select Analyze/Measure, and Analyze/Show Results to get your distance. (Note "O" Street on the image. This is the best road to use to get to more distant places like the golf course.) Note the differences in the straight line and road-line distances between the Cornhusker Hotel and different destinations.

After making your measurements, you now have some hard data to make your decisions on.

Just for fun, try measuring the distances to some of the other points of interest on the image. The airport in Lincoln has been selected as an alternate space shuttle landing site. How long is the runway at the airport? Mom has decided to take the bus to the mall. How far is it from the hotel to the mall? Or you could measure the distances to the various golf courses and try to convince Dad that it would be shorter and faster (and more fun!) to play one of the courses closer to the waterslide park.

Measuring Area

Now that you are starting to get comfortable working with images, let us try another kind of measurement: area. Go back to Analyze/Options and select Area. Click OK to close the dialog box again. Now, what area shall we measure? As you look to the North from the Hotel (to the top left on the image), you see what looks like a small lake: Capital Beach.

Measure the area and distance around the lake by clicking on the Freehand Line tool (click and hold on the measurement tool to get this option), placing the cursor somewhere on the crest and carefully tracing around it. You can start anywhere on the shoreline, but you must click down and go all the way around and come back to your starting point before releasing to close the loop. (If you don't close the loop, NIH Image thinks you measured a curved path and will give an incorrect number for the area.) Then select Analyze/Measure and Analyze/Show Result to see the length of the crest's circumference and the area inside the crest. The area will be in units of square kilometers.

Measure the length across the lake and see how large it is compared to the size of your school.

Now test your skills of observation. There are other lakes in the Lincoln image. See if you can find one and measure its size and area.

Extension Activities

Now that your mind is ablaze with delusions of power, there are endless measurements to be made! How far must you walk if you ride to the Country Club course with dad? How long would it take if you could walk 3 km per hour? How long will it take to walk to the University of Nebraska campus from the hotel? What is the area of the parking lot at the shopping center? How much more area is covered by Mahoney golf course than by the Lincoln Country Club?