SO432, Hydrography

Fall 2000

## Definitions10 @330___________

Short answer    5 @  6        30   ___________

Short answer    1 @ 10        10   ___________

### Essay1 @ 3030___________

Total                        100   ___________

Read the directions carefully.  You have a selection of questions for the definitions and the short answers.

Insure that you devote at least 10 solid minutes on the essay.

Definitions:  define 10 of the 12 terms with a concise sentence that clearly shows your understanding of the term:  Each is worth three points.

(a)    Portolan chart:

(b)   Selective availability:

(e)    Impedance:

(f)     NIMA

(g)    GI&S

(h)    GDOP:

(i)      DPI:

(j)     Lossless compression:

(k)   Large scale:

(l)      Graticule

Answer 5 of the 6 short answer questions and this and the next page; each is worth 6 points.

(1) How do we measure the error in locating positions with a GPS?  Why must we do this statistically?

(2) Differentiate radiometric and geometric corrections for side scan sonar, and give a reason why each type of correction might be required.

(3) What is an ellipsoid, and when must we use it in mapping?  How does the ellipsoid differ from a datum?

(4) How do we apply the concept of map scale to vector and raster data?

(5) What are the differences between the forward and inverse equation for a map projection?

(6) How can we use sonar methods to study the sediment below the surface of the ocean?

At Annapolis: h=1.285     k=1.285

At Annapolis:  h=0.781     k=1.281

You must answer this question; it is worth 10 points.

The two maps on the previous page both have Tissot indicatrices overlaid, and have the values of h and k indicated for the position of Annapolis.

• For each map, indicate the geometric figure used to construct the projection, and state why you chose that figure.
• For each map, indicate what you consider to be the most important characteristic of the projection.
• If you created a large scale map of the area around Annapolis with each projection, would you be able to tell the two projections apart?  Why or why not?

Essay.  This is worth 30 points.

The traditional chart or map was a paper product produced by a mapping agency.  We are now moving to an era of digital maps and charts, and have the capability to make the map into a base for GIS.

·        Discuss the advantages of turning the basic map or chart into a GIS data set, in terms either of an oceanographic research cruise or a naval ship.

·        Discuss the costs of this transformation.

·        Discuss the challenges in designing the map or chart data set, and how decisions in the design stage will affect the ultimate users of the data.