GPS/GIS Midterm

What is the study of geography?

The study of where things are, why they are located there, and how the characteristics of a location influences events taking place there or at nearby locations

How can we use geography?

- Make better use of resources and the natural environment

- Place businesses, schools, and services in locations where they best serve our needs

- Allocate personnel resources to where they are most needed and can do the most good

- Manage or even avoid conflict

- Produce the abundance of food, fiber, and oil crops that feed, clothe, and house us

- Understand the natural world itself

How can we use GIS information?

The information is derived from data, and the data has attributes that can describe the space.

What does the "systems" part of GIS represent?

- Systems means a framework for managing and organizing information, or data

- The system provides sets of tools and functions to interact with, manipulate, explore, analyze, and visualize information

What are the definitions of GIS?

- A spatial system that creates, manages, analyzes, and maps all types of data (ESRI)

- A powerful set of tools for collecting, storing, retrieving, transforming, and displaying spatial data from the real world. (Burroughs, 1986)

- A decision support system involving the integration of spatially referenced data in a problem solving environment. (Cowen, 1988)

Why do we need an information system based on geography?

- The simple answer is "all objects occupy physical space"

- Without this simple and abstract fact, we can't measure distance or area

- Location matters!!

What can we do with GIS analysis?

- provide information with maps

- calculation of areas, distances, route lengths

- measurement of terrain attributes (slope)

- logistics: route planning, vehicle tracking, traffic management

What 3 things does GIS integrate together?

- hardware

- software

- data

What is hardware?

the physical device on which a GIS platform is used: computer, laptop, tablet, cell phone, etc.

What is software?

the digital tool that allows you to capture, organize, analyze, and store data

What is data?

arguably the most significant component of any GIS system

What are some different types of GIS software?

- ESRI - ArcGIS- Market leader, privately owned by Jack Dangermond; Strong in education, government, and business logistics

- QGIS- Free and publicly available; Geospatial data processing tools with extensive plug-in support

- ERDAS IMAGINE- Useful for LiDAR processing

- Harris Geospatial - ENVI- Useful for image analysis, atmospheric correction, hyperspectral data

What are some examples of applied GIS?

- Urban Planning, Management & Policy

- Environmental Sciences

- Political Science

- Civil Engineering/Utility

- Business

- Education Administration

- Real Estate

- Health Care

Spatial data can be used to describe what about objects occupying a geographical space?

- Location: longitude; latitude, (x,y)

- Shape: linear, circular

- Size: 100 acres; 5 km

- Orientation: North to South

How does vector data represent the world?

Uses points, lines, and polygons

- Stores information in x, y coordinates

- Useful for storing data that has discrete boundaries, such as country borders, land parcels, and street

- Has associated tables describing their attributes (e.g., elevation, population size)

How does raster data represent the world?

Stores information of features in a cell-based manner

- Examples are satellite images, photogrammetry, and scanned maps

- Consists of a matrix of cells (or pixels) organized into rows and columns

- A raster image can take many forms, such as .bmp, .tif, .jpg, etc

- Used to store continuous data such as elevation data

What are the characteristics of a point?

- Represented as a single "dot" on the map

- Used to indicate discrete locations

- Usually has a single X, Y coordinate

- Used to represent a feature that is too small to be displayed as a line or area

What are the characteristics of a line?

- Ordered sets of points that have the look of a straight line or a curved arc depending upon the feature it describes

- They have a length but no width

- Used to represent a geographical feature too narrow to have an area, such as a stream or a road.

What are the characteristics of a polygon?

- Closed features whose boundary encloses a homogenous area

- Have an area that is given by the arcs/lines that make the boundary

- Used to represent features that have area

What does raster metadata contain?

- Data image size: # columns and # rows

- Pixel size

- Geographic coordinates of the first (NW corner)and last pixel (SE corner)

- Image projection

What is cartography?

The art, science and technology of map making, the use of maps as research tools and as sources of information, and the study of maps as historical documents and works of art.

What concepts does cartography typically involve?

- Map projection

- Map scale

- Map symbols and legends

- Map generalization

- Spatial data analysis

- Map accuracy and precision

- Map design and layout

What are the two types of coordinate systems?

- Geographic coordinate system: locates objects on the curved surface of the earth

- Projected coordinate system: locates objects on a flat surface (projected maps)

What is a geographic coordinate system?

a reference system for identifying locations on the curved surface of the Earth

What is a graticule?

A network of intersecting lines

What are meridians?

Vertical lines or lines of longitude

What are parallels?

Horizontal lines or lines of latitude

How are geographic coordinate systems measured?

Using degrees, minutes, seconds

What is a geoid?

- Describes the irregular shape of the Earth

- A measurement of mean sea level

- Earth's mass is not uniform at all points and the direction of gravity changes, so the shape of the geoid is irregular

What is a spheroid?

A three-dimensional shape created from a two-dimensional ellipse. The ellipse is an oval, with a major axis (the longer axis) and a minor axis (the shorter axis). If you rotate the ellipse, the shape of the rotated figure is the spheroid

How can GCS latitude and longitude angles be expressed?

- Degrees, minutes, seconds (DMS)

- Decimal degrees (DD): easier to display and compute

What is a datum?

- Mathematical model (i.e., spheroid) that approximates the shape of the Earth to enable accurate position, length and area calculations

- Combines the spheroid and specific origin location to align in the Earth's surface

What is a map projection?

Comes from the concept of projecting a light source through the Earth onto a two-dimensional surface

- Plane

- Cone

- Cylinder

What is a planar projection?

- Produces maps on which the longitude lines converge at the north pole and radiate outward

- Plane will cover the pole and will produce (more) accurate map projection for polar region

What is a conic projection?

- Produces maps with straight converging longitude lines and concentric circular arcs for latitude lines•Cone

- Cone placed over the Earth will cover the midway between the equator and the pole, and it will be a (more) accurate map projection for mid-latitude zones

What is a cylindrical projection?

- Produces maps with straight, evenly-spaced meridians and straight parallels that intersect at right angles

- A cylinder wrapped around the equator and will produce (more) accurate map projection around the equatorial zone

What four spatial properties on a map are subject to distortion?

- Shape

- Area

- Distance

- Direction

What is the universal transverse mercator (UTM) system?

- UTM projection minimizes distortion within that zone

- Divides the Earth into 60 zones

- One zone is a 6° segment of the Earth

- Each zone has a central meridian of 500,000 meters, instead of lat/lon coordinates

What is a map?

- A representation of the Earth's features drawn on a flat surface

- Uses symbols and colors to represent the features in a specific area

What are the 5 types of maps?

- General Reference

- Topographic

- Thematic

- Navigation

- Cadastral

What is a general reference map?

Summarizes the landscape to identify general features and their locations (cities, roads, lakes/rivers)

What is a topographic map?

Summarizes the natural resources and physical landscape features (terrain, elevation, and slope)

What is a thematic map?

Summarizes one particular information or theme (population density, land cover, and geology)

What is a navigation map?

Combines aspects of topographic, general reference and thematic maps to produce navigation maps for ships, boats and aircraft

What is a cadastral map?

General land administrative map for establishing land ownership and supporting land market values

What visual aspects of a map are important?

- Clarity and Legibility: graphic elements must be clear and legible

- Contrast: symbols, lines and other elements should be large enough

- Color: Impact on key information

- Organization of information layers

What are the 8 steps for map production in order?

- Map Question

- Data Selection

- Data Acquisition

- Data Storage

- Projection and Scale

- Cartographic Elements

- Production

- Printing/Display

What are the essential elements of a map?

- Map body

- Legend

- Title

- Scale

- North arrow

- Grid coordinates

What are the optional elements of a map?

- Map projection

- Source of data

- Author

- Date

- Graphs, tables, images, informative text

What is table?

A simple structure to compile and save information as a database

What is a database table?

A collection of related data organized into rows and columns

- Each row is a unique record of a non-spatial characteristic

- Each column contains an attribute field to represent certain data

- Each cell contains a data value

- Each attribute field (column) has associated data type

How can we manipulate the attribute database?

- Data entry & editing

- Sorting data

- Queries

- Data statistics (median, var)

- Data graphs

What are the steps in creating the attribute database?

1. Identify the attributes to be captured

2. Create an attribute field (column) for each attribute

3. Specify the data type for each attribute

4. Write the attribute values in the field (column)

What is a relational database?

A collection of tables that can be connected to each other by unique attributes in a table

What are attribute and spatial queries?

- Two types of queries used in GIS to search for specific features within a layer or multiple layers

- Both can be used individually or in combination to find specific features

- In GIS, these queries can be performed using tools such as "Select by Attributes" and "Select by Location"

What are attribute queries?

- Used to search for features based on specific attribute values or conditions

- Based on the information stored in the attribute table

What are spatial queries?

- Used to search for features based on their spatial relationships with other features

- Can be used to find features that are within a certain distance or area of interest, intersect with another layer, or have a specific topology relationship

- Based on the spatial location and geometry of the features.

What is Spatial Operation?

Used for:

- extracting geographic information or content from data

- compiling new geographic information from other geographic information

- visualizing spatial relations between and among various geographic features