Introduction to Geospatial Technologies, Final

Describe how differential correction and WAAS are similar and how they are different:

Both operate through a series of base stations that calculate position correction information. WAAS only operates within the United Sates. DGPS operates all around the world

Address Parsing:

Breaking an address up into its components parts

Develop a Spatial analysis question and apply the spatial analysis tools of AGOL to this question:

Can you see the big pink building in down town Portland from Mount Hood if you could see that far? Use the viewshed analysis tool.

Predict what will happen when an SQL attribute query is performed on a dataset:

Certain attributes are selected from the attribute table. These attributes are then displayed accordingly to the written SQL.

Describe how the scale of your data affects your map and the map design:

Large-scale maps show a smaller geographic area. Small-scale maps show a larger geographic area.

Ellipsoid:

Larger at its center than at its poles

Equator:

Line of latitude that runs around the center of Earth and serves as the 0 degree line from which to make latitude measurements

Prime Meridian:

Line of longitude that runs through Greenwich, England, and serves as the 0 degree line of longitude from which to base measurements

Boolean operator:

One of the four connectors used to build a compound query

Relational operator:

One of the six connectors used to build a query

Identify the main elements required in map design to effectively communicate information:

Scale bar, north arrow, legend, type of lettering used, labels, fonts, map layout

Spatial query:

Selecting records or objects from one layer based upon their spatial relationships with other layers (rather than using attributes)

Describe the three basic questions that underlie internal map making:

Who will be using it? Is the information on the map being effectively conveyed to the map reader? Is the map well designed and laid out properly?

WAAS:

Wide Area Augmentation System, a satellite-based augmentation system that covers the United States and other portions of North America

List the different types of relational and Boolean operators used in SQL:

=, <>, <, >, >=, <= And, Or, Not, XOR (all data except for what's in common)

Vector data model:

A conceptualization of the world that represents spatial data as a series of vector objects (points, lines, polygons)

Tiger Line Files:

A file produced by the U.S. Census Bureau that contains (among other items) the line segments that correspond with roads all over the United States.

Legend:

A graphical device used on a map that explains what the various map symbols and colors represent

Scale Bar:

A graphical device used on a map to represent map scale

Thematic map:

A map that displays a particular theme or feature

Reference map:

A map that serves to show the location of features, rather than thematic information

Large-scale maps:

A map with a higher value for its representative fraction, such maps will usually show a small amount of geographic area

Small-scale maps:

A map with a lower value for its representative fraction, such maps will show a large amount of geographic area

Buffer:

A polygon of spatial proximity built around a feature

Define a map and discuss the considerations that a map maker must make in designing a map:

A representation of geographic data. Scale bar, north arrow, legend, type, labels, fonts, and layout.

Network:

A series of junctions and edges connected together for modeling concepts such as streets

Define how a spatial query differs from an SQL attribute query:

A spatial query effects spatial relationships that are not based on their attributes. Whereas a SQL attribute query effects attribute relationship that are not based on their spatial locations.

Attribute table:

A spreadsheet - style form where the row consists of individual objects and the columns are the attributes associated with those objects

Suitability index:

A system whereby locations are ranked according to how well they fit a set of criteria

Edges:

A term used for the links of a network

Junctions:

A term used for the nodes (places where edges come together) in a network

Nominal data:

A type of data that is a unique identifier of some kind - if numerical, the differences between numbers are not significant.

Ordinal data:

A type of data that refers solely to a ranking of some kind

Ratio data:

A type of numerical data in which the difference between number is significant, but there is a fixed non-arbitrary zero point associated with the data

Interval data:

A type of numerical data in which the difference between numbers is significant, but there is no fixed non-arbitrary zero point associated with the data

Choropleth map:

A type of thematic map in which data is displayed according to one of several different classifications

Transit Cost:

A value that represents how many units are used in moving along a network edge

Raster data model:

A way of representing spatial data that utilizes a series of equally spaced and sized grid cells

Remote Sensing:

Acquisition of data and imagery from the use of satellites or aircraft

Map algebra:

Combining datasets together using simple mathematical operators

Describe how datums and the geographic coordinate system of latitude and longitude are used to reference locations on the Earth's 3D surface:

Datums are models of the Earth, could be an ellipsoid of geoid. Once determined, the prime meridian is placed through Greenwich, England which represents the zero marker for lines of longitude. Where the Equator, set in the "middle" of the earth will represent the zero marker for lines of latitude. Each line of longitude/latitude will represent a distance (deg, min, sec).

Multipath Errors:

Delay in the signal due to reflecting from surfaces before reaching the receiver

Metadata:

Descriptive information about geospatial data

Explain the formula for calculating the distance from GPS receiver to satellite, D = t * c:

Distance equals the amount of time it takes an object (particle) to reach its goal multiplied by the speed of light, since we are dealing with wavelength signals which are traveling at the speed of light.

Spatial Analysis:

Examining the characteristics of features of spatial data, or how features spatially relate to one another

Describe why geospatial technologies can be considered "geography in action":

Examining your household value compared to the neighborhood. You are using basic geographic concepts of space and place through technology.

Trilateration:

Finding a location in relation to three points of reference

Define the four different types of non-spatial (attribute) data that are linked to spatial (locational) data:

Nominal: Unique identifiers such as a phone number or social security number. It's also names of descriptive information. Ordinal: Ranking system Interval: No fixed zero point. Can have negative and positive numbers - such as temperatures Ratio: Fixed non-arbitrary zero point. No negative numbers

Summarize the three basic systems and tools that make up geospatial technology:

GIS (Geographic Information Systems), GPS (Global Positioning System), Remote sensing

Explain Einstein's Theory of Relativity with respect to the speed of light and satellite timing.

GPS is based on an array of 24 satellites orbiting the earth, each one carrying a precise atomic clock. Most GPS receivers do not have an atomic clock. The satellites are moving at incredibly fast speeds altering the tick speed in comparison to the receiver clocks. The difference in gravity also plays a role in the tick speed. Mathematics are used to fix the GPS tracker to put you in the correct spot.

GIS:

Geographic Information systems, computer-based mapping, analysis, and retrieval of location-based data

GIS:

Geographic information systems, A computer-based set of hardware and software used to capture, analyze, manipulate, and visualize geospatial information

Describe how the discipline of geography is fundamental to understanding geospatial technology:

Geography is why things are where they are. It deals with the spatial characteristics of our planet and spatial relationships and interaction of the people and features that occupy it.

GPS:

Global Positioning System, a technology using signals broadcast from satellites for navigation and position determination on Earth

GPS:

Global Positioning System, acquisition of real-time location information from a series of satellites in Earth's orbit

Differential correction:

Ground based correction where the coordinates are known.

Visual Hierarchy:

How features are displayed on a map to emphasize their level or prominence

What makes geospatial data unique:

It is connect to a real-world location

Describe how spatial data are projected onto a 2D flat developable surface of a cylinder, cone or flat plane:

It is like having a clear globe and putting a light bulb in it and projecting it on the wall. The further the area is from the light bulb the more distorted it is, like the outer edges of the continents. For the cylinder projection we can see that the lines of longitude are evenly placed from each other at a distance. Because the Earth is a globe shape, the lines of longitude come together at the top and bottom. This would make the top and bottom of the map look larger than it actually is. That's why Antarctica looks huge in map projections.

Describe how a GIS allows the user to store and link spatial (locational) data to non-spatial (attribute) data:

It uses an attribute table with records as the objects (spatial data) and fields as the attributes (non-spatial data)

WGS84:

Made for U.S. Department of Defense and is used for GPS.

NAD27:

Made for United Sates and North America

False Easting:

Measurement made east/west of an imaginary meridian set up for a particular zone

Datum:

Model of Earth that is used for plotting locations anywhere on the actual surface of the Earth

Geoid:

Model, places on Earth's surface at mean sea level to try and account for the differences

Describe how and what kind of delays in the travel time of the satellite signal can cause errors in the calculation of a GPS location:

Multipath signals can cause errors in the calculation of a GPS location because the direct signal would have reached the receiver at a faster time. This could be canopy cover, or other kinds of cover that the wavelengths cannot penetrate through.

Describe how the same underlying attribute information can be rendered differently using different data classifications methods (natural breaks, quantile, equal interval, standard deviation):

Natural Breaks: selects class breaks by searching for spaces in the data values. Quantile: Places an equal amount of data values in each class. Equal Interval: Total span of values divided by desired classes, data values are then equally distributed. Standard Deviation: Computes class break values by using the mean of the data values and the average distance a value is away from the mean.

Union:

Overlay that combines all features from both layers

Symmetrical difference:

Overlay that retains all features except the ones in common

Identity:

Overlay that retains all features from first layer along with second layer common features.

Intersect:

Overlay that retains the features that are common to two layers

Know examples how geospatial technology is used in both the private and public sectors:

Public: Wikipedia, GPS, Google Map Maker Private: Companies that with to open businesses in certain locations, marketing

Summarize the basic components of NAVSTAR GPS:

Space segment: satellites and the signals they broadcast from space, Control segment: control stations that monitor the signals, User segment: receivers on the ground

Define spatial thinking and concepts of space:

Spatial Thinking: finds meaning in the shape, size, orientation, location, direction or trajectory, or object, processes of phenomena, or the relative positions in space of multiple objects. Concepts of Space: objects and events have relative position and direction.

Describe how SQL allows the user to create a subset of geospatial data based on specific queries of the non-spatial attribute data:

Structured Query Language uses mathematical functions to allow users to create subsets of geospatial data. It uses one of the relational operators.

SQL:

Structured Query Language, a formal setup for building queries

GNSS:

The Global Navigation Satellite System, an overall term for the technologies that use signals for find locations on Earth's surface

NLCD:

The National Land Cover Database, a raster-based GIS dataset that maps the land-cover types for the entire United States at 30-meter resolutions

PDOP:

The Position Dilution of Precision, describes the amount of error due to the geometric position of the GPS satellites

NAVSTAR:

The U.S. Global Positioning System

Cartography:

The art and science of creating and designing maps

Reference database:

The base network data used as a source for geocoding

Overlay operation:

The combining of two or more layers in the GIS

Describe how the WGS84 and NAD27 datums are created differently, and explain the implication of those differences for finding your location on Earth:

The implication of those difference is they use different references as their zero points. Because of this, they could arrive at the same location but a couple hundred feet away from each other.

Explain how the resolution of a grid cell relates to distance and area on the Earth's surface in the raster data model:

The larger the grid cell the more area it represents of the Earth's surface. The finer the resolution (higher resolution) the more grid cells there are so the clearer the image is and the smaller the scale is. For example, with a finer resolution the scale could be 1:5. For every 1 grid cell there are 5 units of measurement.

Connectivity:

The linkages between edges and junctions of a network

Attributes:

The non-spatial data that can be associated with a spatial location

Geocoding:

The process of using the text of an address to plot a point at that location on a map

Route-finding:

The route that corresponds to the lowest cumulative transit cost between stops in a network

Projection:

The translation of locations on the 3D earth to a 2D surface

Know what a Boolean raster layer represents and how it is used in raster overlay operations:

This is a site suitability.

UTM:

Universal Transverse Mercator, Grid system of locating coordinates across the globe - can't do polar regions

Summarize the difference between the discrete object view (vector data model) and the continuous field view (raster data model) of locations in the real world:

Vector: Points, lines, polygons - fixed locations, or a sixed starting and stopping point Raster: Grid cells, near infinite amount of points - temperatures, elevations, atmospheric pressures, etc. A surface filled with values

Know which datum NAVSTART GPS uses for coordinate locations:

WGS84

Explain the concept of trilateration and why 4 satellites are needed to determine an accurate position on the Earth's surface:

You need three satellites to find your position in a 2D world and the fourth satellite is used to accurately measure the time it should take to reach that satellite. The other three satellites distance could be slightly off, putting you in a different area, but the fourth satellite will correct for that error.

Dissolve:

combine polygons with the same features together

Define the term spatial analysis and provide an example from your discipline:

examining characteristics of features or spatial data. Forest Engineering: examining where soil erosion might be most prevalent and where to build rock buttresses would be best.

NAVSTAR GPS

is one type of geospatial technology, a GNSS, that allows the user to locate their position on the Earth's surface.

Geospatial data:

items that are tied to specific real-world locations