SO432, Geographical Information Systems

Exam 2, Spring 2014


Definitions (pick 10/12)




Maps (no choice)









Read directions carefully. You have a selection of questions for the first part of the exam. Carefully select which questions you will answer, and only answer the correct number.

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



All work on this exam is individual using only what knowledge you are acquired. You may not any reference materials or storage devices (books, notes, computers, stray ink on your person or uniform), and you may not use IM, texting, talking, or any other means to communicate with other individuals.


Definitions: define 10 of these 12 terms with a concise sentence that clearly shows your understanding of the term, and not just that you can find the term in the index or glossary of the text: Each is worth two points.


  1. 2.5D
  2. Drop in the bucket:
  3. Filter a database:
  4. Focal operation:
  5. Graticule:
  6. Integer versus floating point:
  7. KML/KMZ: Google Earth, open standard
  8. Meades Ranch
  9. Quadrangle: standard extents, parallel/meridian boundaries
  10. Shapefile: 3+ files, vector, ESRI, de facto standard
  11. Slope focal operation
  12. Triangulation: TINS and registration
  13. Unregistered image:

Map A covers 3x2


Map B covers 7.5x7.5

Map C shows counties of California sized by population, and covers about 10x10


Discuss the challenges you would have registering the three maps above, which you have as PNG images.   The PNG images show significantly more detail than show up on this page.

         Which would be the hardest to register and why?

         Would any of the maps be a candidate for an affine transformation? Why?

         Could any of these maps easily be replaced with a shapfile? Why?


A GIS tech is digitizing shorelines at the Naval Academy for environmental planning. The southern line has 19 points defining the 248 m long shoreline segment, while the northern has 98 points for 305 m.


Why does the one line contain so many more points, and does that make it better than the other?


Is the tech doing a good job? Why or why not?




You are supporting an infantry battalion planning a raid on a compound, and ordered DEMs showing the area. The battalion commander thinks the two grids he received show the compound at two different times, and wants to know what he could do with DEMs of the same area at different times. Would DEMs from different times be useful? Map algebra

Do you think the battalion commander is correct that these show the area at two different times? If not, is there anything else they could be, and would they be useful in that case? DTM/DSM




The battalion commander is concerned about the holes in the data, and notices that the two displays above (which both show a blowup of the same DEM) seem to have a different number of holes.

Can you explain to him why the display chosen might change the number of holes shown in the data? Focal operation reflectance versus grayscale elevation

Do you have any idea why the holes are where they are?  Flat pond water, which gives a return only directly under the aircraft


What kind of data set is this? What can it be used for?


What features are we seeing in this view, and how can you identify them?