Coordinate Systems and Projections

1. Why do we need to work with projected coordinate systems in GIS? Pick the two correct answers:

a. To convert units of measurement from angular degrees into linear units (meters, miles, feet)

b. To synchronize various data sources that use different coordinate systems to ensure that analysis is consistent

c. To represent coordinates in three-dimensional space for improved visualization

d. To minimize distortion caused from working with three-dimensional data and a two-dimensional computer screen or map

2. What is a datum?

a. A mathematical model of the earth that accounts for its “true” shape (lumps and bumps)

b. A specific point on the earth’s surface used as a reference for measuring distances

c. A mathematical model of the earth and set of reference points that defines the shape of the earth for mapping

d. A coordinate system used to represent three-dimensional spatial data in a two-dimensional computer

3. Which of the following is an example of a projected coordinate system?

a. WGS 1984

b. NAD 1983

c. NAD 1983 New Hampshire State Plane

d. Geographic Coordinate System (GCS)

4. What is projection on the fly?

a. A process spatially aligning different data layers that are in different coordinate systems by temporarily converting them into the coordinate system; this is automatically done by ArcGIS, and the conversion is only effective within the current project; it will not affect the original datasets on the hard drive.

b. A process for mathematically transforming the coordinate system of a dataset when it is added to a GIS project, automatically updating the metadata of all data layers to reflect the current coordinate system used in the project.

c. A process that temporarily transforms data from one format to another to make it compatible with GIS software; this transformation involves converting data files into a format that can be read and processed by the GIS application, ensuring that all data layers can be displayed and analyzed together.

d. A process that generates 3D visualizations of two-dimensional data, done by temporarily creating 3D models by adding an elevation component to the data, which can include terrain details, building heights, and other vertical elements.

5. What is the difference between the tools project and define projection?

a. Project updates the attribute table with new data, while define projection adds projection information to the metadata

b. Project merges multiple datasets into one, while define projections splits the dataset into many layers based on its projection

c. Project assigns a coordinate system label to the data, while define projection mathematically transforms coordinates from one system to another

d. Project mathematically transforms coordinates from one system to another, while define projection assigns a coordinate system label

Quiz 2: Coordinate Systems and Projections

1. Why do we need to work with projected coordinate systems in GIS? Pick the two correct answers:

2. What is a datum?

3. Which of the following is an example of a projected coordinate system?

4. What is projection on the fly?

5. What is the difference between the tools project and define projection?