SO432, Geographical Information Systems

Exam 1, Fall 2008

 

Definitions

10@ 4 points

40

 

Short answers

5 @ 12 points

60

 

TOTAL

 

100

 

 

This is an open book exam. You may use your personal copy of the text book and any notes you have permanently written in it. You may not attach any papers to the book, but you can tab the book.

 

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

 

Quality of your answers is important. For full credit you should use correct terminology, and show that you understand the concepts involved. Demonstration of understanding, and placing you answer in the context of GIS, is much more important than finding a random sentence from the book describing or defining the term, which will be an average answer.

 

All work on this exam is individual. You may not any materials (books, notes, computers), and you may not use IM, texting, talking, or any other means to communicate with other individuals.

 

Red comments are key points, but not complete answers.

 



Definitions: define 10 of the 12 terms with a concise sentence that clearly shows your understanding of the term: Each is worth 4 points.

 

1)      Lossless compression:

2)      Forward projection:  15 skips

3)      ESRI shape file: vector data, actually 3 files

4)      Metadata:

5)      Regional operations:  6 skips

6)      NGA:

7)      Quadrangle:

8)      World file:   (6 skips) no information on datum/projection

9)      RMSE:    6 skips

10)  Meades Ranch:

11)  Map scale:

12)  Precision:


The next five pages contain 5 questions, each of which is worth 12 points. You can answer on the page or on the back of one of the pages. You must answer all 5. For each answer you should clearly show that you understand the principles and use appropriate terminology. 

 

1) How can you develop a feature coding scheme for a GIS database that will have several levels of detail in each category? As an example, consider either the NLCD or the TIGER data sets we have looked at in the labs.

 

2) Use the diagram to answer the following questions:

         Discuss the terms fields/attributes, tuples/records, and relations/tables in relation to the following diagram and indicate why it is important for GIS operations.

         Would this snippet of a data base work well for plotting the locations of earthquakes? Why or why not?

         Would this work for analyzing the earthquake magnitudes?

 

LAT

LONG

MAGNITUDE

 

N39.83

W121.34

MW=7.6

 

N43.76

W118.78

ML=6.4

 

N31.23

W132.67

MS=5.9

 

 

Lat/long are not very precise (2 decimals in degrees are good to about 1 km) but will work well for a lot of plotting since for earthquake studies you often have a very large area.  Bigger problem is that the computer will not like N/S, E/W, and should use +/-.  For the magnitude, putting the units means that you cannot do any numerical computations because the data is in a string field.  You could put them in different fields like MW, ML, and MS, and only put in the values for the one you had, or just add a SCALE field and put the values in that.

  


3) Why should GIS users worry about horizontal datums?

 

 



 

4) The diagram above shows a map projection covering much of the central US.

 

o       Explain the purpose of the markings on the map above, and what they tell you about the map projection used in the map.

 

o       Where does this projection have the least distortion, and how can you tell? Two parallels have h=k=1.00, one through TX-FL and the other through OR-NB-ME

 

o       Could the military use this map for operations? Why or why not?  Only use conformal maps for military operations.

 

o       Can you suggest what projection this is?  Albers equal area conic.


Raster data Vector data

 

5) What are the differences between these two maps above, both of which came out of a GIS? How is the concept of scale applied to each, and what happens to each as you blow them up?