SO432, Hydrography

Exam 1

Fall 2000



Definitions 10 @ 3 30 ___________

Short answer 5 @ 6 30 ___________

Short answer 1 @ 10 10 ___________

Essay 1 @ 30 30 ___________

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:

(c)    Meads Ranch:

(d)   NAD27:

(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.



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.