ENR 3700 Midterm 2 Study Guide
ENR 3700 Midterm 2 Study Guide ENR 3700 (Environment and Natural Resources) Kaiguang Zhao
Popular in Introduction to Spatial Information for Environment and Natural Resources
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This 8 page Study Guide was uploaded by Sophie_ on Saturday March 19, 2016. The Study Guide belongs to ENR 3700 (Environment and Natural Resources) Kaiguang Zhao at Ohio State University taught by Dr. Kaiguang Zhao in Spring 2016. Since its upload, it has received 171 views. For similar materials see Introduction to Spatial Information for Environment and Natural Resources in Environmental Science at Ohio State University.
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Date Created: 03/19/16
ENR 3700 Midterm 2 Study Guide Introduction to Geospatial Information Systems Dr. Kaiguang Zhao Since I’m uploading this a week before our midterm, here’s a reminder of upcoming due st dates! Our 3D hologram homework is due tomorrow, March 21 and the video is limited to less than one minute for the extra credit points. The second homework assignment is also optional— see the last slide in lecture 7 for details! Both can be uploaded through Carmen dropboxes. Many of these notes are derived from our PowerPoint, PDF, or video sources posted by Kai on Carmen. I’ve tried to make them more understandable and digestible so they’re easier for studying and memorizing! Review of Class Terminology Term Definition GIS Geographic information system RS Remote sensing GPS Global positioning system "Geo" Earth "Spatial" In space 2 components of Attribute and location geospatial technology Thematic layers Imagery, elevation, transportation, addresses, boundaries, water features, survey control Liebig's law of Productivity of many living organisms/ecosystems minimum limited by the scarcest nutrient, will lack of geospatial skills become your limiting factor when advancing your career Coordinate systems A frame used to define the locations of geographic entities using some coordinate value. Describe how to use (x,y) values to label a point on earth. Help establish absolute position on earth rather than relative. Alternative/related Spatial coordinate system, spatial reference system, nomenclature coordinate reference system Ellipsoid/Spheroid Earth is not perfect sphere. It bulges near the equator, a model to approximate the shape of Geoid) Geoid Represents the surface of the Earth as if it were caused by gravity alone. It best represents mean sea level. The ocean surface would be hilly...true shape of the Earth. Irregular surface with equal gravity NAD27, NAD83, 3 common datums for USA WGS84 NAD27 Local, created manually by surveying the entire continent, references a single survey point NAD83 Higher precision ellipsoid, compatible with modern survey techniques, used by the federal government and most states WGS84 Used by the entire globe, used for weapons system guidance Geographic coordinate Defined based on spherical coordinates. Units: system decimal degree Projected coordinate Based on projection that transforms spherical system coordinates to flat planar coordinates Shape, area, distance, 4 characteristics that can cause distortion from direction projections What are 2 common Universal Transverse Mercator (defined in meters), PCS for US? State Plane Coordinate System (US state…each state divided into zones) Cartography The sciences, arts, and technologies of making maps Essential map elements Map body, unmapped areas, title, legend, map scale, map symbols, direction, info sources, cartographer, dates, coordinate system Optional map elements Neat lines, inset/locator maps 3 representations of Lexical, graphical, representative (fraction) scale A large scale shows A lot of detail how much detail (1:100) Small scale Not much detail (1:1000000) RF= Map length/Actual length Azimuth Comparable angles measured clockwise from due north (reading from 0 to 360 degrees, only uses North as a reference) Bearing Horizontal angles referenced to either north or south line, divided in quadrants N or S angle between 0 and 90 degrees) True North Direction from any point along a meridian towards the north pole Magnetic North Directions given by the compass and other instruments that rely on the Earth's magnetic field Magnetic Declination Difference between true north and magnetic north Agonic line Line of zero declination where no corrections are required / passes through the eastern section of US GIS A computer-based system for capturing, storing, querying, processing, analyzing, and displaying spatial data 5 components of GIS People, software, hardware, data, methods Vector Use geometry primitives to represent discrete features with a clear spatial location and boundary (points are represented by coordinates) Raster Use a grid and grid cells (pixels to rep features, especially continuous fields such as elevation and precipitation level of detail is greater because it is determined by size of cells) Topology Spatial relationship between geographic features (adjacency, proximity, connectivity) Metadata Data/description that provides information about other data…makes sense of the attribute information table 3 common vector data Shape file, coverage, geodatabase formula Shape File Includes several files can only save one type of feature class (line, polygons, point) / stores only location and attribute table Coverage File Integrated homogeneous set of feature classes (points, lines, polygons stored together) / topology is explicitly stored, contains many features Geodata Base Object-oriented data management file system that is a collection of dataset, feature classes, object classes, and relationship class Geodata Base No separation between attribute and location data, store topology and behavior Rasterizing Divide area into grids and fill those grids occupied by vectors Vectorizing Trace locations of filled pixels along boundaries Image Segmentation A pattern recognition algorithm, ask computer to automatically aggregate pixels in raster images into vector-based objects Digitizing and potential Topological errors (gap, overshoot, spike, mismatch, problems disconnection, measurement errors) Digital Elevation Slope, aspect, and hillside Model (DEM) merges what? Map algebra and raster Use math like expression to process raster layers calculator Mosaic raster images Combining multiple images/raster into a single one, often apply algorithms to cope with overlapped areas or no-data areas Buffer Rings drawn around features at specific distance from future Merge Combines features of an input theme with similar features from an adjoining theme to produce an output theme that contains the attributes and full extent of both themes Dissolve Aggregates features that have the same value based upon some attribute Clip/Mask Cookie cutter, no altering of attributes Intersection Cut an input theme with the features from an overlay theme to produce an output theme with features that have attribute data from both themes GPS Tells your current location and is a space-based radio navigation system 3 segments Space, control, user Space A constellation of 2 to 32 GPS satellites Control A network of ground-based monitoring stations GPS receivers User Standard positioning Free and available global positioning system service What can GPS tell us? current position with reasonable degree of accuracy - display a line of past positions and store them -store a large number of known locations and provide a range and bearing to them -gives real-time estimates on progress to/from location (ETA) -provide estimated altitude, keep accurate time Trilateration Use satellites as reference positions via the concept of intersecting spheres What 2 things must you Satellite position, receiver-satellite distances know for GPS to work? Distance=velocity*time To see how long it takes for a radio signal to get from the satellite to the receiver use What are the sources of Satellite, receiver clock, accidental/intentional signal error when using a jamming, poor visibility, atmospheric interference, GPS? multiple signals, selective availability, poor satellite geometry (DOP) PDOP Positional dilution of precision, indicator or the geometry of satellite constellation, accounts for both #s of satellite available and their relative locations to each other The lower the DOP Better the GPS measurement. value, the How to get better GPS Use DGPS measurements. DGPS Differential GPS. Increases accuracy dramatically. Use one stationary and one moving receiver to help overcome the various errors in signal. Stationary receiver is located on a precisely known control point. Correction factor derived from stationary receiver, broadcasted to other receivers. Shx Index file. Each record contains the offset of the corresponding main file record from the beginning of the main file Dbf Table file, contains feature attributes with one record per feature Prj Projections definition file, stores coordinate system info Georeferencing Converts scanned paper maps or ungeoreferenced images into spatially referenced data by adding spatial coordinate info GIS Data Sources and Applications: Another lesson about safely unplugging the USB drive • This is the lecture that Kai had to record again due to his corrupted PowerPoint file. GIS • Define problems/tasks • Gather data o Download, GPS, telemetry, digitizing, remote sensing, field work, etc. • Process and analyze data o Query, map algebra, viewshed analysis, buffer, intersect statistical model, query, union, etc. • Interpret and report the data and info o Map, graphic, table, writing, video, equations, hologram, etc. Places to obtain or download data 1. Produce your own data 2. Purchase commercial data (some can be very expensive) 3. Download from a public domain a. Federal data sources: USGS, US Census, NOAA, NASA, USDA, EPA, DOT, US Fish & Wildlife Service, US Forest Service, Data.gov (192,687 datasets) b. State and local government sources: Ohio DNR, Ohio EPA, City of Columbus (Columbus.gov), Ohio Geographically Referenced Info Program (ogrip.oit.ohio.gov) Data availability • Get metadata and data to fit your needs. Use common sense and be smart about it! • Metadata is descriptive information needed to make sense of your data. It usually includes information about the publisher, data, file format, description, spatial references, scale, its accuracy, lookup table, etc. Applications of GIS • There are many of them. • GIS can be used in virtually any field. Examples: • The first spatial analysis was performed regarding public health and epidemiology: 1854 Broad Street cholera outbreak in London. • Public health is a focus area that is increasingly making use of GIS. • Human-climate interaction: the evolution of our languages is influenced by climate. o Climate-shaped human languages § Tonal languages require humidity • Global ecology: public webcam and climate-vegetation interaction • Marine biology: use of satellite telemetry o E.g. Mary Lee • Sociology: mapping environmental attitude versus footprint “The application of GIS is limited only by the imagination of those who use it.” –Jack Dangermond, President of ESRI The first law of geography • Nearness is closeness in space, in the strict sense. In the general sense, closeness is anything: time, income, age, species, education background, ethnic group, interest, etc. Homework 2 • Use the following websites (or just Google) to find a successful GIS application in areas of your interest, and then write a one-page essay to describe what you found and your thoughts about potential utility of GIS to your future career (Due March 28 on Carmen). o http://www.esri.com/industries o http://www.esri.com/software/arcgis/arcgisserver/success-stories o http://www.esri.com/software/arcgis/arcpad/success-stories o http://www.esri.com/software/arcgis/extensions/businessanalyst/success-stories o http://www.esri.com/partners/hardware/geospatial-experts/case-studies
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