Example SURE 425
Exam Questions
- Define the following terms: object, instance feature,
heuristic
- How does the Spatial Data Transfer Standard (SDTS)
differentiate between a point and a node? Give an example
of each. SDTS has three specialized spatial object types:
complete chain, area chain, and network chain. What are
the differences?
- What are the benefits of the National Spatial Data
Infrastructure (NSDI)? Identify the steps needed for
implementation of the NSDI. Several challenges are
presented in the Strategic Plan for the NSDI. Identify
and describe four of them.
- Metadata is data about data. Describe four of the data
elements for metadata. What are metadata? What is the
value of metadata from both the user and producer
perspective? What are the major uses of metadata?
- What is the National Geospatial Data Clearinghouse and
how will it be used?
- There are two extremes in the conceptual model of space:
entities and continuous fields. Describe them.
- Examples of practical forms of spatial reference are the
specific Cartesian or azimuth coordinates. Identify and
give an example of three other spatial referencing
devices.
- To be useful, a GIS must provide a toolbox to the user
that will meet the capabilities they envision. To do so,
the system must fulfill a number of capabilities.
Describe the conditions which a GIS must fulfill.
- What is the importance of the measurement scale? Give a
specific example.
- Your employer just returned from a convention where
he/she frequently heard the term spatial/geographic
information system. They know you studies GIS at Ferris
and ask you to describe a spatial information system to
them. What is your answer?
- Convert the hexadecimal value 02C to its binary
equivalent.
- What is the difference between a simple list and an
ordered list?
- There are two extremes in the conceptual model of space:
entities and continuous fields. Describe them.
- Describe the difference between a regular tessellation
and an irregular tessellation.
- In a vector model, nodes carry important information.
Explain.
- Convert R7, C9 to the Morton Order. What is the row and
column number for Morton position 28? Given a sample data
set, find the (a) row order, (b) row-prime order, (c)
Morton Order, and Peano Order.
- One of the properties of regular tiling is shape (also
self-similarity). What is it and why is it important in
tesselations?
- Given a sample data set, show the quadtree representation
of that data.
- Using tesseral arithmetic, determine whether the quadtree
leafs 0332 and 2 are adjacent. Using the notation x,y
where x is the quadtree leaf and y is the value for the
leaf, explain how you would find the quadtree structure
by overlaying two maps. Find the quadtree structure and
the leaf attributes for a derived map by overlaying two
input maps defined by their quadtree structure and leaf
attributes.
- The Octahedral Quaternary Triangular Mesh (O-QTM) was
introduced by G. Dutton. Describe this method of global
tessellation. What are the advantages of the O-QTM
tessellation? Describe how the O-QTM has a built in
mechanism for documenting scale and accuracy. The basic
form of O-QTM is a series of 8 triangles covering the
globe. Explain the process of subsequent divisions.
- When acquiring digital data from a data supplier, we need
to consider the data characteristics to see if they are
compatible with the application. Give a few concrete
examples.
- What is the difference between interpolation and
extrapolation?
- What is the difference between a pointwise and global
method of interpolation? Describe the advantages of using
trend surfaces as global interpolators. How is a
pointwise random-to-grid interpolation performed? Give a
graphical example. Describe the two different methods
used in patchwise methods of interpolation. What are the
advantages of a patchwise model over a global model of
interpolation?
- Describe two different general sampling schemes used in a
DTM. What is progressive sampling? Explain how it works.
Describe systematic sampling for a DTM extraction and
explain why this method is favored by the photogrammetric
operators. Identify weaknesses in using a random sampling
scheme in DEM data collection.
- Describe the process of picking a TIN model from DEM data
using the VIP (Very Important Point) algorithm. Use a
sketch with your description. How is the Fowler and
Little algorithm employed in creating a TIN model? How is
the drop-heuristic method employed in creating a TIN
model.
- Sketch the Delaunay triangulation for eight points given
in a figure by linking points in the figure. Is the line
segment EG in the Delaunay triangulation? Explain why or
why not. Given the elevation data for the figure, show
how the ridge line between two points can be maintained
within a Delaunay triangulation.
- What is the general position assumption? What is the
empty disk property and how is it used in Delaunay
Triangulation? A regular grid is not a general position
assumption. How can we act on the grid points so that the
general position assumption is fulfilled?
- Explain a strategy for determining if a point lies within
or without a polygon. Use a sketch along with your
explanation.
- Describe the procedure used in the Douglas-Peucker
algorithm and give a graphical example.
- Describe two of the elements of line generalization.
- What is the purpose of line simplification? How is a
three point moving window used in line simplification?
Give a graphical example along with your written
explanation. One method of line simplification is the
retention of only a fraction of the points within the
data set. What are the disadvantages of this line
simplification method? Also give a graphical example.
Describe the Jenks' linear simplification algorithm.
- Find the shortest Euclidean, Manhattan and Network
distance from point A to point B in an accompanying
figure.
- The fractal dimension indicates how measures of the
object change with generalization. Explain. What is the
Steinhaus Paradox? How is the fractal dimension
determined? What is the difference between geometric and
statistical self-similarity?
- What are the important criteria for an ideal curve?
- Describe what a TIN model is. Describe how distance
ordering is used to triangulate a TIN.
- Using the 4-connectivity model (or 8-connectivity model),
draw the drainage network for this DEM. If a channel
starts only when the flow reaches a volume of 3, what
does the channel network look like? Remember to define a
tie breaking rule (state in your answer) and enforce it.
- What is a pit in a DEM? Explain the process of flooding
pits to form lakes. How is the Base:Height ratio
important in measuring DTM photogrammetrically?
- Describe how the minimum enclosing rectangle is used in
line-line intersections. Graphically show this with an
example.
- Describe three sources of error in spatial data. Describe
the National Map Accuracy Standards (NMAS). What are the
differences between Engineering Map Accuracy Standards
(EMAS) and the ASPRS standards for large-scale mapping?
Koppe's formula is an alternative to the NMAS. Explain.
- Your company has decided to submit a request for a
proposal to implement a GIS for a county containing a
large metropolitan area with a lot of surrounding farm
land. The company has put together a team to draft the
proposal with different members leading the discussion on
different areas of the project. As the survey engineer,
your task is to study the issue of creating a digital
terrain model. Assume that this county has data to some
degree under different formats. Select a method for
creating the DTM and justify the selection, keeping in
mind the applications of this data by the different
departments within the county. Also, clearly identify the
realistic assumptions for this hypothetical study.
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This page is maintained by Bob Burtch and
was last updated on 19 October 2000.
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