Data Formats & Models

1) A data model is a set of rules/constructs used to describe and represent aspects of the real world in a computer.  The two types of data models are vectors and rasters.  Vectors use coordinate data to represent spatial information through points, lines, and polygons, while rasters represent spatial information through grids, where each grid cell has a value, and all grid cells together form an image. 

2) Topology is the study of geometric properties that do not change when the forms are bent, stretched or undergo similar geometric transformations.  Topology is important because it is necessary to represent vector data neatly and accurately, even though its forms usually are warped in some way.  Topological vector models also effectively represent adjacency, connectivity, containment, area definition, and contiguity.

3) A vector data model would be best for representing hillside slope, through a topographical map.  The vector data model effectively shows many contour lines, which is the best way to show elevation and slope.

4) In a raster data model, as cell dimension (the real-world area represented) increases, the level of detail decreases.

5) Four types of attribute data are nominal, ordinal, interval, and ratio data.  Nominal data is descriptive/categorical data, and can be image, such as of a building.  Ordinal data is ranked/ordered data, such as a bar graph ranking states by economic growth.  Interval data is ordered data, with absolute differences in magnitude and absolute zero, such as on a scale, where numbers are different based on their position on a scale.  The scale of a map is an example of interval data.

6) Two types of vector data file formats are shapefiles and coverages.

7) Two types of raster data file formats are grids and images.

8) It is not possible to select features in ArcCatalog.

9) The world.mdb dataset does not contain a feature dataset; it contains feature classes.
10) The feature classes are cities, countries, disapp_area, and world30.

11) Flight_path.lyr is a shapefile.

12) It is possible to add data to an ArcMap document by selecting Add Data from the File menu, or by dragging the data from an ArcCatalog window.

13) There are 699 features in the disapp_area feature class, according to the table window of the preview menu in ArcCatalog.