Image resolution describes how large an object must be in order to be resolved by a satellite sensor. In a 4 kilometer-resolution APT image each pixel is 4 km x 4 km; in a 1 km-resolution HRPT image, each pixel is 1 km. x 1 km. The smaller the area in each pixel, the more detail in the image.

### Use your artwork to demonstrate differences in resolution

1. Have students draw any multicolored picture they like on the graph paper that has the smaller squares.
2. Then have students lightly draw lines on the graph paper that mark off squares the size of the larger graph paper's grids. Thus each larger square should have four smaller squares contained within it.
3. Students then determine the average color represented in each larger square. Have them draw that color on a new piece of graph paper with the larger squares. Is the new drawing recognizable? What is the resolution of each pixel in the drawing?
4. Using the original artwork, the students then determine the average color represented in each of the smaller squares. Have them draw that color on a new piece of graph paper with the smaller squares. Now are the drawings recognizable? What is the resolution of each pixel in the drawing? What features are still not represented in the pixel drawing?

### Resolution in Satellite Imagery

To compare resolutions, take a photograph of the same person or object at a distance of 2 feet, 10 feet, 20 feet, and 100 feet.

Then look at archival satellite images of the same view of Earth at different resolutions.

### Materials

• crayons or colored pencils
• graph paper with two different size grids (i.e. 1 cm x 1 cm and .5 cm x .5 cm)