SO432, Hydrography

Fall 2001

## Definitions10 @330___________

Short answer    2 @ 10        20   ___________

Figures         2 @ 10        20   ___________

### 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 15 solid minutes on the essay.

Quality of your answers is important.   For full credit your should use correct terminology, and show that you understand the concepts involved.

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)    NIMA

(f)     GI&S

(g)    DPI:

(h)    Lossy compression:

(i)      h and k:

(k)   Flattening:

(l)      Raster:

Answer 2 of the following 3 short answer questions.  Each is worth 10 points.

(a)    Your GPS reports the coordinates of your position to be about 500 m from the position on your map.  Can this be possible without either the GPS or your map being wrong?  Why or why not?

(b)   Discuss the parts of the GPS system, and how each is involved to provide you with an accurate location.

(c)    Discuss how a sidescan sonar uses a sound wave to paint a “picture” of the bottom.  Insure that you specify what is measured and how that is translated into a pixel on the screen.

You must answer this question, worth 10 points.

Several common geometrical forms can be used as the basis for a map projection.

·        List the forms

·        If an example is available in the figure below, identify it and state how you recognized it.

·        If an example is not available below, state why none of these projections uses that particular geometric basis.

·        You may or may not need all 4 figures, and you might not have enough figures for all the geometric forms.

You must answer this question, worth 10 points.

The figure below shows four map projections.

·        Explain what the overlaid circles and ellipses tell you, and how these projections differ.

·        Explain which of the projections might be used by NIMA for a large scale operational map, and why.

Essay.  This is worth 30 points.  You should use correct terms and show that you clearly understand the concepts involved.

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.

·        What is the difference between a map and a chart, and can that distinction change in the digital age?

·        What are our choices in how we design the storage of  digital data, and do those choices affect the utility of the digital products?

·        What is the concept of scale for maps, and does this concept still make sense in a digital world?