Lab 3

1. What is a data model? Describe the two most commonly used data models.

A data model is a set of rules/constructs used to describe and represent aspects of the real world in a computer. The two most common types of data models are vector and raster models. Vector models consist of points, lines, and polygons. They are most useful in representing non-continuous data, such as a river, city, park, etc. Raster models define features as a set of cells in a grid. They are most useful in representing continuous data, such as elevation, pollution levels, rainfall, etc.

2. What is topology and why is it important?

Topology is the study of geometric properties that do not change when the forms are bent, stretched or undergo similar geometric transformations. They are important because they capture and record relationships between features. These may include adjacency, connectivity, and containment.

3. What type of data model would be best for representing hillside slope? Justify your answer.

A raster data model would be best for representing a hillside slope. This is because a slope has continuous changing data that would be very difficult to display in a vector model. Each cell in a raster model can contain the different elevations at that particular location, as opposed to having to draw contour lines.

4. Describe the relationship between spatial detail and cell dimension with regard to raster models.

Resolution is the relationship between spatial detail and cell dimension. The larger the cell dimension the lower the resolution, and the smaller the cell dimension the higher the resolution.

5. What are the four types of attribute data? Give an example of each.

The four types of attribute data are nominal, ordinal, interval, and ratio. Nominal data is descriptive/categorical data. An example would be mammals, birds, reptiles, etc. Ordinal data is like nominal data but it has some sort of rank or order associated with it. In college undergrad students are freshman, sophomore, juniors, and seniors. However, the amount of time they have spent in each category may vary from one person to the next. Interval data has ordered data and the differences between the values are constant, and zero is arbitrary. An example would be temperature (not including Kelvin). Ratio data is also ordered data, but it has an absolute data. Temperature measured in Kelvin fits into this type since it has an absolute zero.

6. List two types of vector data file formats.

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

7. List two types of raster data file formats.

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

8. You can do all of the following in ArcCatalog EXCEPT:

a. Identify features

b. Copy data

c. Select features

d. View metadata

c. Select features

9. In the Chapter 4 exercises, does the World.mdb geodatabase contain a feature dataset?

No

10. What are the names of the feature classes contained in the World.mdb geodatabase?

Cities, countries, disapp_area, and world30 are the different feature classes.

11. What data format does the flight_path.lyr layer file reference?

It is referencing a shape file.

12. What are two ways to add data to an ArcMap document?

One way to add data to ArcMap is to click the add data button on the standard toolbar. The other way to drag the data from ArcCatalog

13. How many features (records) exist in the dissap_area feature class? How can you determine this using ArcCatalog?

There are 699 records for the dissap_area feature class. In ArcCatalog you click on the Metadata tab and then the Attributes tab. Under the attributes there will be details for disapp_area, and it lists the number of records.

14. Complete the ESRI online module “Basics of the Geodatabase Data Model” and post a screenshot of the certificate.