Geo 365

Front 1

Define:
Geospatial data

Back 1

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.

Front 2

Explain:
Vector data vs. Raster data

Back 2

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.

Front 3

Define:
Geometries and Attributes as the two components of GIS data.

Back 3

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

Attributes describe the characteristics of spatial features.

Front 4

Explain:
Georelational data model vs. Object-based data model.

Back 4

The georelational data model uses a split system to store geometries and attributes.

The object-based data model stores geometries and attributes in a single system.

Front 5

How does data exploration differ from data analysis?

Back 5

Data exploration involves the activities of exploring the general trends in the data, taking a close look at data subsets, and focusing on possible relationships between data sets.

Data analysis uses GIS commands to perform operations on data.

Front 6

Name the 5 examples for vector data analysis.

Back 6

1) buffering
2) overlay
3) distance measurement
4) spatial statistics
4) map manipulation.

Front 7

What are the 4 operations for raster data analysis.

Back 7

1) local
2) neighborhood
3) zonal
4) global operations

Front 8

What are the 3 levels of approximation of the shape and size of the Earth for GIS applications?

Back 8

1) Sphere

2) Spheroid or Ellipsoid

3) Geoid

Front 9

Define:
1) Sphere
2) Spheroid/Ellipsoid
3) Geoid

Back 9

1) Simplest model used in map projections for approximating Earth.

2) More accurate approximation accounting for the minor and major axis.

3) Most accurate approximation accounting for Earth's irregular surface and irregularities in density.

Front 10

Why is the datum important in GIS?

Back 10

A datum is important in GIS because it serves as the reference or base for calculating the geographic coordinates of a location.

Front 11

Describe the three types of map projections by the projection or developable surface.

Back 11

1) A cylindrical projection uses a cylinder as the projection or developable surface.

2) A conic projection uses a cone.

3) An azimuthal projection uses a plane.

Front 12

How is the scale factor related to the principal scale?

Back 12

The scale factor is defined as the ratio of the local scale to the principal scale. In other words, the scale factor is the normalized local scale.

Front 13

The geographic coordinate system is defined by _______ and _______.

Back 13

Longitude and latitude

Front 14

What is a meridian?

Back 14

Another term for lines of longitude.

Front 15

What is the range of longitudes (in degrees)?

Back 15

0 to (+/-) 180

Front 16

What is a parallel?

Back 16

Another term for lines of latitude.

Front 17

What is the range of latitudes (in degrees)?

Back 17

0 to (+/-) 90

Front 18

Name two commonly used projected coordinate systems that are based on the transverse Mercator projection.

Back 18

1) Universal Transverse Mercator (UTM) grid system

2) State Plane Coordinate (SPC) system.

Front 19

How do you convert coordinates of degrees-minutes-seconds (DMS) to decimal degrees (DD)?

Use 45*52'30" as an example

Back 19

DMS: 45*52'30"
=
(45 + 52/60 + 30/3600)
=
DD: 45.875*

Front 20

Define:
Datum

Back 20

A mathematical model of the Earth, which serves as the reference or base for calculating coordinates for locations.

Front 21

What are 3 commonly used datums?

Back 21

North American Datum of 1927 (NAD 27)

North American Datum of 1983 (NAD 83)

World Geodetic System of 1984 (WGS 84)

Front 22

What spheroids are NAD 27 and NAD 83 based on?

Back 22

NAD 27 is based on Clarke 1866

NAD 83 is based on GRS80

Front 23

What is the purpose of a map projection?

Back 23

To display 3-dimensional information in 2 dimensions.

(i.e. 3-D spheroid to 2-D map)

Front 24

What is the primary use and benefit to WGS 84?

Back 24

It is the datum for GPS readings

Front 25

Which datum is used for GPS readings?

Back 25

WGS 84

Front 26

The line of tangency between the projection surface and the reference globe...

Back 26

Standard line/parallel/meridian

Front 27

________ is the normalized local scale, defined as the ratio of the local scale to the principal scale.

Back 27

Scale factor

Front 28

What are the 3 coordinate systems commonly used in the United States?

Back 28

1) Universal Transvers Mercator (UTM) grid system

2) Universal Polar Stereographic (UPS) grid system

3) State Plane Coordinate (SPC) system

Front 29

How many zones is the UTM grid system divided into?

Back 29

60 zones

Front 30

Explain:
On-the-fly Projections

Back 30

Data sets are automatically converted to the coordinate system denoted by the first data set in display.

Front 31

Name the three types of simple features used in GIS and their geometric properties.

Back 31

1) A point has 0 dimension and has only the property of location

2) A line is one-dimensional and has the property of length.

3) A polygon is two-dimensional and has the properties of area (size) and perimeter.

Front 32

What are two important functions of topology?

Back 32

1) It ensures data quality, such as lines meeting perfectly and polygons closed properly.

2) It can enhance certain types of analysis such as geocoding and traffic volume analysis

Front 33

What are the two advantages of using shapefiles as opposed to topology-based data such as coverages?

**Hint: think outside the program**

Back 33

1) Shapefiles can display more rapidly on the computer monitor

2) Shapefiles are non-proprietary and interoperable, meaning that they can be used across different software packages.

Front 34

Explain the relationship between the geodatabase, feature dataset, and feature class.

Back 34

Geodatabase, feature dataset, and feature class form a hierarchical structure.

A geodatabase can contain one or more feature datasets, and a feature dataset can store one or more feature classes that share the same coordinate system and area extent.

Front 35

Describe the difference between the geodatabase and the coverage.

Back 35

The difference between the two models lies mainly in the composite features of regions and routes.

The geodatabase does not support the region subclass and replaces the route subclass with polylines with m (measure) values.

Front 36

Explain the two differences between the georelational data model and the object-based data model.

Back 36

1) The object-based data model stores both the spatial and attribute data of spatial features in a single system rather than a split system.

2) The object-based data model allows a spatial feature (object) to be associated with a set of properties and methods.

Front 37

What are the 4 basic elements of the raster data model?

Back 37

1) cell value
2) cell size
3) raster bands
4) spatial reference

Front 38

What is the main advantage of using a raster data model vs. vector data model?

Back 38

Rasters have fixed cell locations.

Front 39

What is the main disadvantage of using a raster data model vs. vector data model?

Back 39

Rasters cannot display the precise locations of spatial features.

Front 40

What are two examples of integer rasters?

What are two examples of floating-point rasters?

Back 40

Interger:
Land use & soil types

Floating-point:
Precipitation & Elevation

Front 41

Explain the relationship between cell size, raster data resolution, and raster representation of spatial features.

Back 41

A larger cell size means a lower resolution and greater difficulty in representing spatial features with cells.

Front 42

Calculate the number of rows and columns using resolution....

You are given a 30-meter DEM:
UTM coordinates (in meters) at the lower-left corner are (560635, 4816399) and the coordinates at the upper-right corner are (570595, 4830380)

Back 42

Rows = (URy - LLy)/res.
= (4830380 - 4816399)/30
= 466


Columns = (URx - LLx)/res.
= (570595 - 560635)/30
= 332

Front 43

What is the general formula for determining number of rows and columns from coordinates and resolution?

Back 43

Rows =
[(UpperRight-y) - (LowerLeft-y)]/resolution

Columns =
[(UpperRight-x) - (LowerLeft-x)]/resolution

Front 44

What are the 5 methods for producing a DEM?

Back 44

1) Stereoplotter and aerial photographs

2) Contour lines

3) High-resolution satellite imagery

4) Radar data

5) LIDAR data

Front 45

Explain the difference between lossless and lossy compression methods

Back 45

A lossless compression method allows the original image to be precisely reconstructed.

A lossy compression method cannot reconstruct fully the original image but can achieve high-compression ratios.

Front 46

What is vectorization?

Back 46

Vectorization refers to the conversion of raster data into vector data.