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C188 FINAL Exam Study Guide with 207
Questions and Answers
spacial data - objects located in space, usually cartesian plane, x,y can references objects in relation to one another georeferenced/geospatial data - spatial data that has been located in reference to a standard coordinate system for the earth in long/lat transaction processing systems - computer processing where computer responds to user requests (yelp, uber) decision support systems - programs that analyze data and present it so users can make decisions, local fire/flood study spacial data model: vector - points, lines, polygons; complex data structure geographic feature components - geographic positions, attributes, spatial relationships, time basic questions for GIS - location, condition (where), trend (what changed), routing (best way), pattern, modeling (what if) any cell rule conversion -
all cells touching near cell center rule for conversion - only nearest cell touching topological model - TIN - Triangulated irregular network quantile - Each class contains an equal number of features. Well suited to linearly distributed data. standard deviation - Shows how much a feature's attribute value varies from the mean. Class breaks are created with equal value ranges that are a proportion of the standard deviation (usually at intervals of 1, 1/2, 1/3 r 1/4 standard deviations using mean values and the standard deviations from the mean) equal interval - Divides the range of attribute values into equal-sized subranges; best applied to familiar data ranges, such as percentages and temperature natural breaks - Based on natural groupings inherent in the data; best group similar values and maximize the differences between geometric interval -
Geodesy - science of measuring the shape of the earth geoid - a less lumpy version of the earth, based off variation of gravitational pull on the earth (as if the earth was all liquid) bathymetry - the measurement of depth of water in oceans, seas, or lakes ellipsoid - a way of assigning a set of coordinates (lat,long) to location; we cant measure with it bc degrees of longitude not constant; we try and get it to fit the geoid, but we have to make sacrifices (ex: we can get it to fit Europe, but other areas will be way off=datum datum - the way we use the ellipsoid to fit the geoid, coordinate system and set of reference points used to locate places on earth, define geographic coordinates for a region WGS84 - world geodedic system, tries to fit the entire world NAD 83 - north american datum, tries to fit north america as best as it can, includes Canada and Mexico projection - making the curved ellipsoid flat to fit a planar coordinate system so we can transform lat and log into meaningful units (ft, meters); 3 types: plane, cylindar, cone; each projection preserves different aspects of the data
precision - the number of digits that can be stored in the field; if precision > 6 chose double, if precision < 6 chose float scale - the number of decimal places for float and double fields map essentials (TODALS) - title, orientation, date, author, source distortions in projections -
- equal area projections: preserve area by assigning then an area on the map proportional to area on earth
- conformal projections: preserve the shape of small features and show directions (navigation)
- equidistant projections: preserve distances to places UTM (universal transverse mercator) - divides world into zones, each 6 degrees wide; coordinates discontinuous across zone boundaries; Nor-Cal is zone 10 vertical datum - measures elevation cylindrical projections - used for maps of the entire earth conic projections - used to represent mid-latitude regions
digitizing - the process of transforming spatial data from a hard copy to a digital file, use a mouse/cursor remote sensing - the process of collecting data about objects or landscape features without coming into direct contact with them; preformed form orbital or sub-orbital platforms using instruments which measure electromagnetic radiation emitted from the terrain geodetic center of north america - Meades Ranch , Kansas remote-sensing: 1st order elements -
- tone- variation form black to white
- color - multitude of combinations of hue, value, chroma
- resolution - the ability of the entire photographic system (lend, exposure, etc) to render sharply defined images remote-sensing: 2nd order elements -
- Geometric arrangements of objects: size and shape
- Spatial arrangement of tone/color: texture, pattern remote-sensing: 3rd order elements -
- locational or positional elements: site (how objects arranged in respect to one another or terrain; aspect, topography, etc) and association
- interpreted from lower order elements: height and shadow stereoscopy -
the science and art that deals with the use of binocular vision for the observation of overlapping photos or other perspective views *stereoscopic vision=ability to see ad appreciate depth of field though perception of parallax GPS - A Us owned entity started in 1978 US Department of Defense - decided the military needed a positioning system and created GPS How many satellites make up GPS? - 27 (24 in operation and 3 in case one fails) 11,000 miles in space One satellite lasts 10 years How Does GPS Work? 5 reasons - 1.Trilateration from satellites
- Distance measured using the travel time of a radio message
- Timing - atomic clocks (4 in each)
- Satellites position in space
- Signals travel through atmosphere Trilateration from satellites - 1st- one satellite locates a point somewhere on sphere with satallite in center 2nd-does the same and narrows search based on intersect 3rd- where all three intersect Signals travel through the atmosphere -
NextGen - FAA plans for a new GPS system that will show planes location in real time McHarg's Suitability Habitat of the model - practical technique for landscape planning that is the basis for much of the work in GIS Desegregation/aggregation -
- the process of overlay disaggregates the spatial polygons and aggregates the attributes AND - intersection OR - union Various types of Point Buffers - simple buffer- overlap dissolved compound buffer- overlap identified nested buffer topology - set of points, lines and areas which obey specific rules Conflation -
- two maps referring to the same phenomena, if geo-referenced correctly, should coincide when the two maps are overlaid
- if they are not matched up then you must conflate in order to get them together Edge Matching - builds a single and continuos map
Editing Functions - functions that add, delete and change deposition of features Line coordinate Thinning - redundant data is thinned to reduce volume, VIP points controlled by operator Sliver polygons - result of coastline weave removing slivers - areas are small long and thin slivers generally have only 2 bounding arcs while real polygons rarely have 2 alternating attributes Fuzzy Tolerance - defining a tolerance limit for each indicates the amount of uncertainty applied to each line Data Reduction: - classification: thresholding data fields into clusters Generalization: making classification less detailed by combining classes Binary model - simplest form of preference building +1 and - 1 Raster -
- Spline
- Kringing DEM - digital Elevation model Discrete features -
- using raster to do vector like analysis two fundamental types of analysis: - vertical- simple cells and Map Algebra allow us to recombine layers rapidly Horizontal- regular partitioning of the earth aids in measuring the characteristics of a cell's neighboring cells Map algebra- values of true and false (whats the deal) - any non zero input is considered to be true any zero is considered to be false Merge Function - join two or more discrete rasters Mosaic Function - join two or more continuous rasters cell by cell analysis - looks at one cells neighborhood and then returns a value to that cell Zonal Statistics tool - measure a grids characteristics then join summary into a polygon shape file Discrete Data -
intermediate values are not permissible Continuous Data - permissible to calculate intermediate values 1st law of geography - everything is related to everything else, but close things are more closely related Thiessen polygons - a cellular network of polygons Delaunay Triangulation - the dual of the Thiessen or Voronoi Polygons
- proximal method that satisfies the requirement that a circle drawn through the three nodes of a triangle will contain no other node advantages to the TIN model -
- deals with regular data from grids
- it can deal with irregular data such as spot elevations
- it can deal with contour lines
- ability to describe the surface at different level of resolution disadvantages to tin - more processing is needed can be slow and need huge computres flat triangles - generated along contours when the sample points occur along the contour at a distance that is less than the distance between contours LIDAR -
branching circuit Location-allocation - improve or opimize demand conditions by allocation of supply Location Allocation: Spatially unconstrained vs Spatially constrained - Spat. Unc- demand and supply interact in straight lines and the friction of travel remains constant Spat Con- models that are embedded within a line network, where each segment has individual constraint parameters (speed) point-point class - supply and demand are reported at an actual point location location set covering - models which minimize the required facilities to serve demand maximal covering - maximize coverage with a fixed number of facilities polygon to polygon class - uses polygon data rather than points to create a constrained service region creates a complex polygon spatial interpolation - Estimating the value of a variable of interest at an unsampled location based on the values measured at sample locations adaptive - intelligent sampling - sample pattern dictated by data variability
Global vs Local Estimators - Global- use all sample points to estimate values at unsampled locations Local- estimates are based on neighboring points Exact vs Inexact Estimators - Exact- the values at input sample locations will have same values in the output surface Inexact estimators will create an output surface where even the values at the original sample locations may be estimates Deterministic vs stochasitc methods - deterministic: based on a mathematical model Stochastic: based on a geostatostocal model that incorporates random variation and accounts for spatial autocorrelation Inverse Distance Weighting - estimates the value of an attribute at un-sampled points using a linear combination of values main factor affecting IDW - power parameter weight diminishes as distance increases arbitrary power parameter Spline Function - creates the smoothest possible line along the set of points Global polynomial interpolation - Global polynomial interpolation (GPI) fits a smooth surface that is defined by a mathematical function ( a polynomial) to input sample points
A Satellite in 2008, which features a panchromatic sensor with a spatial resolution of 0.41 meters. Myth of Satellite Resolution - has 1:50,000 scale accuracy Myth of accuracy for practical applications - Satellite remote sensing has 90% accuracy 1st order elements of image interpretation - tone, color, resolution 2nd order elements of image interpretation - size, shape, texture, pattern 3rd order elements of image interpretation - site, association, height, shadow point scale - scale at a point with a specific elevation on the ground Means every point on a vertical photograph will have a different vertical scale Stereoscopy - the science and the art that deals with the use of binocular vision for the observation of overlapping photographs or other perspective views and the method by which such views are produced spectral resolution - number and size of the bands which can be recorded by a sensor Image Classification -
multispectral image classification and segmentation used to differentiate land cover classes based on their spectral response for production of thematic map products WGS84 - What datum are GPS stellite locations reported in NAD84 (2011) - What datum are GPS stellite locations reported in for the United States Wide Area Augmentation System - WAAS: a large scale continental differential GPS system made by the FAA. Accuracy of 3m, 95% of the time. geosynchronous satellite transmission - Satellite that stays in the same location all the time (over the US). used to alert aircraft when it has a problems using a GPS transmission. disaggregation of spatial polygons - creating more fragments from overlay aggregation of spatial polygons - combining more fields in one record Floating point grids - raster sets with continuous variables with decimal place Integer grids - raster sets with discrete values merge - join two or more discrete rasters
