69 Cards in this Set
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Translation
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Only + and - (no multiplication or division)
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Rotation
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angles, cos, sin
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Scale
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Multiplication and visions where the size of the object is changed (change axis scale)
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Skew
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Changes it shapes
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Georeferencing... how many control points do you need?
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Only put in the number of points that are required to transform the map (unless you really want to warp the original image permanently)
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Image transformations: 1st order
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affine: parallel lines parallel
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Image transformations: 2nd order
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2d curve constrained only at control points
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Image transformations: 3rd order
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more curvature but only at control points
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spline
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smooth but through all control points
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adjust
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local rubber sheeting
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georeferencingtool limitations
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does not take elevation into account, "fit" only at control points
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Why model in gis?
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dangerous environments, understanding processes, concept validation
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Models: what are they?
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representations of reality
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Static models
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linear
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Dynamic models
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iterative, deterministic, stochastic
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What does stochastic mean in dynamic modeling?
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Introducing a random variable into a process that you do repeatedly, something is slightly different each time
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What are random numbers?
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They arent really random. sometimes they can be if through a physical process but if its being generated through a computer its not really "random"
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Types of models:
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digital, analog, agent based, cartographic models
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Simulation of processes: why?
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Try before you buy, avoid danger, avoid mistakes
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Automation issues
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neighbors, cell size, cell shape, wraparound, edge effects
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How do you find a "fairly high place" if given a digital elevation model?
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Something over the average height. Take the DEM and find the average elevation in a region and then find the elevationsthat are within 1 standard deviation from that mean. things that are fairly high will be 2 st deviations from the mean, but not 3 (that would be high)
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How do you find peaks and ridge lines?
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these are locally high places
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How can you use elevation variance to determine the roughness of terrain?
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In practice it doesn't really work because the standard deviation of a sin wave and a congruent line are both 100. how else do you determine surface roughness?
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Proxies
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Peaks, fairly high, smooth, not too steep, westerly views
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Modeling issues
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experimental, empirical control, between case, within case, synchronic
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Modeling limits
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reduction of a complex problem, factor selection, sensitivity to small modifications, error estimation
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Modeling benefits
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inexpensive, safe, allows incorporation of qualitative factors, makes possible exploration of space, facilities participation by stakeholders
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Prism clusters
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defining clusters of people by neighborhoods (upper crust, blue blood estates, empty nesters)
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Ethical issues of GIS and privacy/ethics/ responsibility
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GIS displays as tools for persuasion, digital slavery, money and GIS
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Legal issues of GIS
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copyright laws, freedom of information act, liability
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Technical issues of GIS
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ecological fallacy, modifiable area unit problem, error propagation
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You are given dots, how do you connect them?
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There are many ways to connect them. Without an order, you dont know how to connect the dots. Its a simple issue if you have the boundary of the community, and you have GIS points, then you know there is an order to map the community. But if you're doing data mining, and you need to conne…
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Why would somebody buy something they can get for free? why would there be a sale of public information?
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because the data has been combined andformatted, it may be very convenient to buy it rather than do all the workyourself. Formatting, checking something, just to produce what YOU’REinterested in.
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TEMPEST
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emissions security --- recovering of plain text by capturing electromagnetic or acoustical energy.
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Plain text recovery
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electromagnetic radiation from video. eavesdropping risk -- by picking up and decoding electromagnetic interference produced by the equipment, it became clear this type of information theft was easy
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Data security
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passwords, file hiding, field hiding, locks and keys
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Gerome dobson and geoslavery
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using GPS to track people
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WHY GIS?
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costs (high start up), benefits
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Benefits of GIS
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direct (cost reduction), indirect (information exchange, competitive advantage, visualization tools)
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List direct benefits and indirect benefits for having GIS in an agency:
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direct: effectiveness of cost reduction and innovation of sales
indirect: information exchange and greater understanding
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direct costs of GIS
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hardware and software, training, learning curve
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Indirect costs of GIS
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reliance on computers, turnover, working environment
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what is the fifth essential element of GIS?
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data display (VISUALIZATION)
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six primary visual variables:
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orientation, size, shape, value, hue, texture
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Design elements
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scale, color, titles, symbols, text, legend
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scale
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publication requirements, level of detail, appropriate symbols
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Additive light is....
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RGB
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Subtractive dyes are....
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CMYK
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when would you use additive (light) RGB?
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if you're going to use the map on a website or LED screen
(RED GREEN BLUE)
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WHen would you use subtractive (dyes) CMYK?
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If you're printing on an ink jet printer, or on a book/poster, you should use CMYK
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RGB
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red, green blue
LCD, CRT projector
web display
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CMYK
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-Cyan, Magenta, Yellow, BlacK
-Inks, dyes
-printed map
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GIS tradition, "4 will suffice"
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you can color any map using only 4 colors
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DPI (whats an appropriate DPI and what is unacceptable) --- and what does DPI stand for!?
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Dots per inch
450 DPI can capture all of the details, 225DPI things start to dissolve, 100 DPI is unacceptable
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Absolute location
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longitude, latitude, height
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Relative location
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proximity, distance, direction
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contextual location
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place, spatial environment
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Located based service delivery: examples??
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cell phones, smartphones, hybrid devices
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data mining
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discovering patterns in data using artificial intelligenceor database sstems… the main goal of the data mining process is to extractinformation from a data set and transform it into an understandable structurefor further use. can be used to increasesales, promote new product, based on you…
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Advantages to internet GIS
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· Local control over final map scale, center, projection,layers
· Time sensitive information updated by server
· Changes in data sets controlled by servers
· Reduction in redundant storage
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Disadvantages to internet GIS
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· Trust in server
· Increased metadata requirements
· Loss of local control
· Loss of redundancy
· Disaster potential
· Language problems
· Privacy issues
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Anoto digital paper
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Digital paper, pen, bluetooth... Looking at a dot could tell you where you are ona piece of paper up to ½ mm. a set of dots so uniquely designed that thedistance and direction seen by a video pen can tell you where you are. Thatmeans that with a little video pen with Bluetooth attached to…
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What is LIDAR?
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Light emission and ranging... high quality elevation models.
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Does LIDAR result in a DEM or DOQ?
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a DEM. They have nothing to do with a DOQ
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Toblers first law of geography
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everything is related to everything else but nearer things are more related than distant things
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Advantages of using GIS model builder tool? why not just do it?
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First, it provides its own documentation. The model that you see on the screen is what is run. You can make a script. Export and make a script from it. Second, you can change the criteria and run the program again without having to start over. Its faster. you can run it again with a diffe…
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Whats an agent based model?
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based off one individual person/animal/ automobile. Some avatar. Its not on 100 things... it follows ONE THING THROUGH A PROCESS
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Map algebra:
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Some neighborhood operators. And you have some global and local raster map algebra operators.
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If I take a raster grid full of numbers and another raster grid full of numbers and I add numbers, is that global or raster math?
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local raster math
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GRG 360G: Final