Paint By The Numbers

Description: A pencil and paper activity demonstrates how astronomical spacecraft and computers create images of objects in space.

Objective: To simulate how light collected from a space object converts into binary data and reconverts into an image of the object.


Materials: (per group of two students)

Transparent grid
Paper grid
Picture of house
Pencil

Procedure:

1. Divide students into pairs.

2. Give one student (A) in each pair the paper copy of the grid on the next page. Give the other student (B) in each pair the picture of the house on the next page. Instruct student B not to reveal the picture to student A. Also give student B a copy of the transparent grid. (See notes about making student copies of the picture and grids on the next page.)

3. Explain that the picture is an object being observed at a great distance. It will be scanned by an optical device like those found on some astronomical satellites and an image will be created on the paper.

4. Have student B place the grid over the picture. Student B should look at the brightness of each square defined by the grid lines and assign it a number accord-ing to the chart above the picture.
Student B will then call out the number to student A. If a particular square covers an area of the picture that is both light and dark, student B should estimate its total brightness and assign an

intermediate value to the square such as a 1 or a 2. Note: The letters and numbers on two sides of the grid can assist the receiving student in finding the location of each square to be shaded.

5. After receiving a number from student B, student A will shade the corresponding square on the grid. If the number is 0, the square should be shaded black. If it is 3, the square should be left as it is.

6. Compare the original picture with the image sketched on the paper.

Discussion:

In this activity, the student with the transparent grid represents an astronomical spacecraft. The picture is the object the spacecraft is trying to image. The student with the paper grid represents the radio receiver on the ground and the image processing computer that will assemble the image of the object.

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Last modified prior to September, 2000 by the Windows Team

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