Sequence | Background | Objectives | Materials | Activity | Extensions | Evaluations

TOPIC-TITLE Deep Sea Technology - Making an Image AUTHOR Michael DiSpezio Roger Torda (JASON IV-Deep Sea Technology Authors) GRADE SUITABILITY Upper and High Elementary SCOPE Oceanography

Sequence Review the basics of sonar as presented in the previous activity. Explain that by "sweeping" the sound across an object, modern SONAR technology can produce extremely accurate three-dimensional views of underwater objects. Sometimes an image-enhancing technique called false coloration is applied to acquired data. To produce a false color image, sonar return times are sent to a computer. The computer processes this information and uses it to "paint" an image of the target with bright, distinct colors. < < go top

Background Summary SONAR equipment provides accurate imaging and measurement of subsurface features that are not easily accessible. By comparing and contrasting the times required for echo detection, computers can compile a precise three-dimensional profile of an underwater target. < < go top Objectives Students will be able to do the following: Learn how SONAR used to construct images. Construct a profile of a vent chimney. < < go top Materials Overhead projector Transparency made from Master 2.3b, SONAR Imaging (used in previous activity) Transparency and student copies made from Master 2.3c, Profile Grid of a Hydrothermal Vent Chimney Erasable transparency markers for teacher demonstration Crayons or markers for student use < < go top Activity Project Master 2.3b, SONAR Imaging. Review how this master was used to illustrate the previous activity. Then, use overhead markers to color in the image's blank boxes. Explain that this type of false coloration helps scientists identify details of the SONAR image. Distribute student copies of Master 2.3c, Profile Grid of a Hydrothermal Vent Chimney, and project the transparency made from the same master. Use colored markers to fill in the key at the bottom of the master. Then color in several grid boxes for each time range. When you are confident that the class understands the activity, have students color in their own grids accordingly. When students have finished coloring their grids, have them compare their completed false color representations. Ask the class: Does the revealed image appear similar to the illustration on the master? (Yes, it should.) What do the different colors represent? (Parts of the vent chimney at different distances.) Why is it advantageous to use false coloration? (It brings out details that would be lost in a plain black-and-white image.) < < go top Possible Extension For younger students Supply students with crayons or markers and have them compile false color images of familiar shapes such as cones, cubes, and cylinders. For older students Have students select a familiar classroom object and produce a false color image of the object as it might be detected by SONAR. Explain that false coloring is frequently used in a high technology medical scanning technique called Magnetic Resonance Imaging (MRI). MRI images of internal body parts allow physicians to study internal tissues without invasive surgery. If possible, obtain several false color images from a local hospital or laboratory. < < go top Teacher Evaluation Review how false color images are produced and used to illustrate three-dimensional features. Describe the role of the computer in producing this high technology display. < < go top