Chapter 1 Review Questions

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Chang, GIS, 9e Chapter 1 Review Questions

• Define geospatial data.

Geospatial data are data that describe both the locations and characteristics of spatial features such as roads, land parcels, and vegetation stands on the Earth’s surface.

• Describe an example of GIS application from your discipline.

[Refer to Section 1.2 and describe an example of GIS application from geography, forestry, geology, environmental studies, business, public health, etc.]

3. Go to the USGS National Map website (http://nationalmap.gov/viewer.html)

and see what kinds of geospatial data are available for download.[Go to the above website, follow the instructions at the website, and check for geospatial data available for download.]

• Go to the National Institute of Justice website

(http://www.ojp.usdoj.gov/nij/maps/) and read how GIS is used for crime

analysis.[Go to the above website. “Learn about Crime Mapping” is included in the lower right corner. It lists three topics: What is GIS; Mapping Crime: Principle and Practice; and Understanding Hot Spots.]

• Location-based services are probably the most commercialized GIS-related

field. Search for “location-based service” in Wikipedia

(http://www.wikipedia.org/) and read what has been posted on the topic.

Accessed on August 9, 2010, Wikipedia defines a location-based service as “an information and entertainment service, accessible with mobile devices through the mobile network and utilizing the ability to make use of the geographical position of the mobile device.”

• What types of software and hardware are you currently using for GIS classes

and projects?[Name the software package (e.g., ArcGIS 10.2) and the hardware (e.g., PC Windows 7) for the GIS class.]

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• Try the map locators offered by Microsoft Virtual Earth, Yahoo Maps, and

Google Maps, respectively. State the major differences among these three systems.[Go to each website, try the map locator, and summarize, in your opinion, the major differences between the map locators.]

• Define geometries and attributes as the two components of GIS data.

Geometries describe the locations of spatial features, which may be discrete or continuous. Attributes describe the characteristics of spatial features.

• Explain the difference between vector data and raster data.

Vector data use points and their x-, y-coordinates to represent spatial features of points, lines, and areas. Raster data use a grid and grid cells to represent the spatial variation of a feature.

• Explain the difference between the georelational data model and the

object-based data model.The georelational data model stores geometries and attributes of spatial features in separate systems, whereas the object-based model stores them in a single system.

• Provide an example of mashup mapping.

[We can superimpose a map showing state parks on Google Earth. We can even attach a short description to each of the parks.]

• Why is "volunteered geographic information" useful for disaster

management?VGI is useful for disaster management because it can provide near real-time data with images and descriptions to decision makers.

13. The following link, http://www.openstreetmap.org/#map=12/52.1977/0.1507,

shows a map of Cambridge, England based on OpenStreetMap data. Use the map to compare the quality of OpenStreetMap data with Google Maps.[You can place OpenStreetMap and Google Maps side by side for comparison. The highways and streets seem to match well. It would require superimposition of the two maps to make an accurate comparison, which is not possible for this question.]

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• Suppose you are required to do a GIS project for a class. What kinds of

activities or operations do you have to perform to complete the project?[The project will most likely involve data input, data management, data display, data exploration, data analysis, and, in some cases, GIS models and modeling.]

• Name two examples for vector data analysis.

Examples for vector data analysis include buffering, overlay, distance measurement, spatial statistics, and map manipulation.

• Name two examples of raster data analysis.

Examples of raster data analysis includes local, neighborhood, zonal, and global operations.

• Describe an example from your discipline, in which a GIS can provide useful

tools for building a model.[A GIS can be used for building simple models. For more complex models such as environmental models, a GIS is typically used for data visualization, database management, and data exploration.]

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Chang, GIS, 9e Chapter 2 Review Questions

• What is a datum?

A datum is a mathematical model of the Earth, which serves as the reference for calculating the geographic coordinates.

• Explain the difference between NAD27 and NAD83.

NAD27 is a local datum based on the Clarke 1866 ellipsoid, a ground-measured spheroid, whereas NAD83 is a geocentric datum based on the GRS80 (Geodetic Reference System 1980) ellipsoid. NAD83 is a more accurate reference than NAD27.

• What is WGS84?

Developed by the U.S. Department of Defense, WGS84 is a global reference system for supporting positioning and navigation. It is the datum for GPS readings.

• Pick up a USGS quadrangle map of your area. Examine the information on

the map margin. If the datum is changed from NAD27 to NAD83, what is the expected horizontal shift?[The expected horizontal shift is listed on the lower margin of a USGS quadrangle map.]

5. Go to the NGS-CORS website (http://www.ngs.noaa.gov/CORS/). How many

continuously operating reference stations do you have in your state? Use the links at the website to learn more about CORS.[Go to the above website, click a state on the map, and see how many continuously operating reference stations are within the state.] Surveyors, GIS professionals, engineers, scientists, and others can apply CORS data to position points at which GPS data have been collected. The CORS system enables positioning accuracies that approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically.

• Explain the importance of map projection.

A map projection offers a couple of advantages. First, a map projection allows us to use two-dimensional maps, either paper or digital, instead of a globe. Second, a map projection allows us to work with plane or projected coordinates rather than longitude and latitude values. Computations with geographic coordinates are more complex.

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