exam 1 ans 2 Flashcards

Question

What is a Coordinate system?

Answer 1

A coordinate system is a way to describe a spatial feature/entity relative to a center -What are coordinates: ways to reference location on map

Answer 2

1.decimal/degrees 2.degrees/minutes/seconds -Represents a world ellipsoid

Answer 3

-Is a grid system that works by dividing the world into a series of zones, and then determining the x,y coordinate for a location in that zone -Determine zone of intrest (ex 17N) then determine position with easting (6 digit) and northings (7 digit) -projected coordinate system -good for large scale

Answer 4

-Cartesian grid based system (like UTM) Created in the 1930s. Used for US city and county data mainly -Zones are formed following state and county boundaries. Every state is split between north and south while UTM splits the world, referenced in feet

Answer 5

-Coordinates the number -Datum is the year measurements taken -projection is then the distortion

Answer 6

-Used to transfer the spherical earth (3D) onto a 2D surface, Allows for the systematic arrangement of parallels and meridians on a flat surface representing the geographic coordinate system (ex lat and long) - introduce some level of distortion (bc flattening image)

Answer 7

1. Distance (maintains equidistance relationships so distance from centre is the same no matter what direction) = equidistance 2. Area (areas have proportional relationships to their corresponding features on the earth) = equal area 3.Direction (maintained when angles are portrayed correctly in any direction) = azimuthal 4.Conformity/shape (maintains angles, so no N/s, E/W lines intersect at 90 degrees, but at expense of distance = conformal)

Answer 8

-Distances at center are true but the distortion in other properties increases as you move away from the center point. - Area is distorted -Distance is very distorted towards bottom of image -Scale is for the most part preserved Used in the United States and other large countries with larger east west than north south extent one main type: -(Albers equal area) -Scale and distance are distorted north to south but maintained west to east -Areas are proportional and the directions are true

Answer 9

-Continuous picture of the earth, Countries near the equator in true relative positions -Distance increases between countries located toward the top and bottom of image. View at the poles is very distorted. -Area for the most part is preserved -Mercator works at local and global near the equator but the farther you go it is not very good for a local projection

Answer 10

-Flat paper on globe and wherever the paper touches the globe is the center point and where accuracy is conserved -Part of earth is visible; not the entire globe just partial; maybe more hemisphere or continent. View is half of globe or less -Distortion occurs at all four edges. -Distance is for the most part preserved; good if distance is variable of study - mainly used for polar research

Answer 11

-Ways to understand distortion of projections -geometric deformation indicator that is an infinitely small circle on the surface of the earth projected as a small ellipse on a map projection plane. It helps depict distortions (areal, linear, angular)

Answer 12

real features found on the earth's surface real features that have been transformed and represented in a digital world Digital objects and their associated attributes and values represent geographic entities

Answer 13

PAL Points (fire hydrant, trees): aka nodes, labels Area (census areas, land use): aka arcs (points with lines from front point to end point), polygons (closed figure). A closed string of coordinate points that are connected by nodes and vertices and arcs --> sized and perimeter properties Lines (roads, rivers): aka arcs, polylines. A string of coordinate points that are connected by nodes (the start points and end) and vertices and arcs X Y will say HOW the points were derived

Answer 14

1. Determining discrete vs continuous features 2.World is constantly changing (ie, urban sprawl), therefore so do entities

Answer 15

1. Vector (point, line, area (polygon)); discrete method of data created with vertices, nodes, arcs --> stored as topological tables////geographic (ie. GPS)coordinates to store the location of a geographic entity 1. Large scale= more detail 2. Small scale= less detail 2. RASTER (grid, pixels); Continuous - assign different properties to each cell on the grid - dont have signitfigent attribute table, if they do then it is based on the pixel value -based on a grid -->columns and rows to create pixels

Answer 16

1. Non- topological characteristics: -No tables -Cant shift node/boundary and expect all the data to shift with it; doesn't have framework -Over and undershoot cannot be fixed without topology; cant do things automatically like connect nodes 2. Topological (NOT TOPOGRAPHY) geometric relationship that exist between entities located it space. It can be thought of as the study of how entities are organized relative to one another, whether they are adjacent; connected; or contained; Helps to detect errors in spatial data (-Identify entity, Know its going to become object, Either place map on digitizer and trace OR interacting digitizing characteristics 1.Computer will recognizse start nodes, vertices potentially, and the arcs 2.Computers will make polygons, tell you which ones interact, the number of nodes and the arcs etc.

Answer 17

Adjacency: the information about the neighbourhoods of different entities Contained: the information about entities that enclose other spatial features Connected: the information about the links between entities

Answer 18

- Used to describe and depict spatial entities that are continuous across a landscape - Raster data are representing by an array/grid of cells in rows and columns - each cell contains a value that describes the phenomena being examined (a measurement or description). cells are usually called picture elements (pixels) - there are many but some broad groupings are: CRSQ 1. Chain coding 2. Run-length encoding/block coding 3. Simple rasters 4. Quadtrees

Answer 19

1. cell size -refers to x and y dimension of each pixel -important because the raster layer has one value associated with each pixel --> only one type of land can be represented in each cell 2. cell value -unique nominal, ordinal, or interval/ratio scaled value associated with each type

Answer 20

- raster data must be georeferenced to relate them with other spatial datasets -referenced using a coordinate system that is related to the number of rows and columns in the layer - the georeferenced values can be interpolated within individual pixels

Answer 21

-reduces data volume on a row by row basis -stores a single value where there are a number of cells of a given type in a group, rather than sorting a value for each individual cell -block coding: extends run length encoding approach to 2 dimensions by uitilizing groups of square blocks to store data

Answer 22

- reduction is based on the boundary of the entity/feature -the boundary in this case is defined as the sequence of unit cells starting from and returning to a given origin -the direction of travel around the boundary is usually given a number or letter system

Answer 23

Start with vector data set containing polygons with associated attributes a grid with the desired cell size is superimposed. The polygons which contain the centres of each of these grid cells are then determined the values of the grid cells become the values of the attributes of the polygons which contain them

Answer 24

Start with gridded satellite classification with class numbers contained each grid cell borders between differing class numbers are located polygons are then generated for each contiguous area by storing the x, y coordinates of the points along these borders

Answer 25

-Rester is larger -Vector data sets have much smaller data especially for simple geographical entities

Answer 26

-rastr can be done with only quadtrees -vector is good for topological questions (adjacency, connectivity, and containment)

Answer 27

-raster scale increases which leads to "blocky" images creates problems if resolution is high -vector handles scale and rotational changes better because entities are stored as precise coordinates

Answer 28

-raster models are better at 1. surface modelling and interpolation 2. analysis of continuous and complex data sets -vector models are better at 1. analysis involving discrete spatial entities 2. simple overlays and geometric operations

Answer 29

-Backbone of how raw data is stored and how information is generated from it -A collection of related data

Answer 30

DEOTSSO 1. Data management systems (DBMS) can house large quantities of data and allow multiple users to work on the database concurrently 2. (data)Evolve in a database 3. (in) One location, therefore reduced redundancy 4. Transfer user knowledge between applications 5. (data) Sharing is encouraged 6. (data) Security and standards for data acessc an be developed and enforced 7. (If) Organized, maintenance costs are reduced and there is a reduced data application

Answer 31

Structure/organization turns DATA into INFORMATION and efficient management of INFORMATION gives it VALUE

Answer 32

DATA is RAW collection and then turns INTO information

Answer 33

1. order data 2. re order data 3. summarise data 4. combine data in order to obtain information of value

Answer 34

1) shared manner 2) easy access 3) with concurrent access (simultaneous) 4. minimum data duplication 5. with integrity (validity) ensured

Answer 35

store attribute data associated with spatial data in a GIS store topological data associated with spatial data in a GIS store metadata associated with spatial data in a GIS overall make querying of spatial data possible

Answer 36

- a data model to represent real world objects in a digital context stored in a computer -a data load capability- tools to help import and load data into the database structure -indices- help speed up searches -

Answer 37

-engine filters out to different types of database -more about thinking things through 1) Data investigation -why are you collecting the data and what aspects do you need? -type, quantity or quality, choosing the right entity and attribute 2) Data relationships - when you have multiple tables, understand the relationships between entities and their attributes 3) Data design and structure -what software? field names, structures, types are you going to develop? 4) The database -how do you populate database? process? how is data maintained/upgraded?

Answer 38

1. one to many 2. many to many - multiples compared to multiples, these WILL NOT JOIN 3. one to one - a unique value to a unique value (there is not more than one) 4. many to one -help used decide of the proper tables for their relational database

Answer 39

1. Entity sets: the fundamental thematic groupings or phenomena being modelled 2.Relationship sets: “subsets of the cross product of two or more entity sets” ex the subset of hotels in a certian town 3.Mappings: which define the relationship between the members of entity sets, may be one to many, one to one, many to many

Answer 40

1) Single files (a database type) -AKA flat files -Spreadsheets; the data is stored in columns (fields) and rows (records) -Useful for smaller datasets -Will have limited impact on computational speed or storage space 2) Relational databases (a database type) -Related to one another via unique identifiers that allow users to link two or more databases or tables together -The unioque identifer can also be referred to a primary key in the origin table -The same field in the adjoining (destination) table is called the foreign key -If both tables have the same field name in each database, this is referred to as the common key

Answer 41

1. Inputting the result of a classification or computation 2. Allows specificity for the type of data field you require 3. Removed redundant or unnecessary fields 4. Improves storage capacity and processing time

Answer 42

1. Single record; typing and changing that record only 2. Multiple records; calculate command; these records are selected first and then updated with a specific value or classification

Answer 43

1.Select by attribute so ask questions for data via its attributes 2. Select by location so select data based on their proximity to other features 3. Use standard query language (SQL) -Syntax or SQL statements (using = ) -Boolean connectors (using “and:” or “or)

Answer 44

the indication of how good the data are; overall fitness and suitability of data for a specific purpose 1. “Garbage in-garbage out” (aka GIGO) --> need good data because biggers decisions will be based on it 2. Error prone data -Can affect the reliability of the final product -Lead to misinterpretation of the final product, affects decision making -Provide inaccurate measurements or models -Provide inaccurate results of queries

Answer 45

1. Metadata -Metadata is “data about the data” ; the 5 W’s, scale, projection and coordination, transformation, and usage 2. Understanding accuracy vs precision -Accuracy is the extent to which estimated data values approach its true value ex. Plus or minus two meters -Precision is the recorded level of detail of your data ex more decimal points 3.Understanding errors -Errors are flaws in data; the difference between reality and the GIS computer environment -Errors can be single, definable departures from reality ex. The easting and northing location for one water monitor was entered incorrectly -Errors can also be persistent widespread deviations throughout a whole database ex easting and northings for all water monitor locations was everted incorrectly 4. Completeness -Will cover the entire study area and time period; complete set of attributes in database 5. Compatibility -Is the data used together sensibly? Data should be collected and captured using similar methods ex are the overlays at the same scale 6. Consistency -Applies not only to separate data sets but also within individual data sets 7. Applicability -Appropriateness or suitability of data for a set of commands, operations, analysis or to solve a specific problem

Answer 46

1. Bias -Systematic variation of data from reality -Can be technical or human based 2. Resolution -To describe the smallest feature in a dataset that can be displayed or mapped -Raster is figured out by cell size --> whatever the set cell size is and larger seen -Vector is determined by scale of the original map, the point size, and line width of the features represented thereon and the precision of digitizing 3. Generalization -Simplifying the complexities of the real world to produce scaled models and maps

Answer 47

-International organization of standards (ISO) -important because Protects an institution or organizations data investment 1. Helps user understand data 2. Enables discovery 3. Limits liability 4. Highlights prudent data stewardship 5. Reduces workload associated with questions about data 6. Reduces overall costs in the long term

Answer 48

conceptual errors: Errors stemming from our knowledge and understanding and trying to model reality. 1. Ecological fallacy; the assumption that an individual from a specific group or area will exhibit a trait that is predominant in the group as a whole --> take one individual context and apply to everyone/whole 2. MAUP (modification areal unit problem); a challange that occurs during the spatial analysis of aggregated data in which the results differ when the same analysis is applied to the same data, but different aggregation schemes are used 3. Mental Maps 4. Individual perception of reality 5. Spatial models used to reflect reality; vector and raster 6. Coming from different backgrounds/disciplines; reductionist view (detailed, explains parts of a system ex biology), OR holistic view (broader, tried to explain interrelationship at meso and macro scales)

Answer 49

1. Survey data -Operation of equipment (GPS) -Incorrectly inputting the wrong attributes into the database 2. Remote sensing data or air photos -Georeferenced incorrectly -Misclassification (clouds or shadows in an image) -Time sensitive 3. Maps -Digitizing process -Generalization -Boundaries (fuzzy)

Answer 50

1. Source map error continuous data -Fuzzy boundaries -Map scale -Map measurements 2.Operational -Mainly focusing on digitizing process (map registration) -Human error; psychological, physiological, line thickness, method of digitizing (point vs stream mode)

Answer 51

1. conceptional errors: Errors stemming from our knowledge and understanding and trying to model reality 2.Errors stemming from source data 3.Errors in data encoding 4.Errors in data editing and conversion 5. Errors in data processing and analysis

Answer 52

1. Considered “last line of defense” against errors -Cleaning and editing is done by scrutinizing the work – manual -Cleaning and editing is done by automatically by setting parameters, tolerances, and topography rules within the software to help detect errors (vector) -Minimize misclassifications by eliminating “noise” from easter cells, this can be rectified by filtering and reclassifying each cell to meet the trends in the data 2. Conversion -Raster to vector -Topological problems -Vector to raster -Loss of connectivity vis topological errors -Loss of small polygons -Change to grid orientation -Change to grid the origin and datum

Answer 53

GIS analysis techniques can bring in error 1. Classification; what intervals used to classify; reflectance values for each pixel within a specific wavelength 2. Aggregation/disaggregation; is aggregating smaller to larger than no problem 3. Integration through overlay procedures

Answer 54

1. Visual inspection: Cleaning, editing, and comparing your output with the source data 2. Double digitizing: Map is digitized twice 3. Error signatures: Each person digitizing does it differently. If they make the same mistakes, they become identifiable to that individual; “their error in signature” 4. Statistical analysis: outliers, error modelling (epsilon), error bands around digitized lines (Monte Carlo)

Answer 55

1.Error detection 2.Management accountability 3.External accountability 4.Quality reporting

Answer 56

1.Source 2.Data capture method 3.Editing and cleaning procedures 4.Conversion and transformation 5.Identifying known errors

Answer 57

The generation of a unique purpose polygon that is a specified distance around a point, line or area feature

Answer 58

Positive buffering: Buffering algorithm identifies the geometric coordinates of a line exactly n units away from a point, line or feature. Identifies x and y of the beginning node, intermediate vertices and the ending node Point buffering: buffering around a point creates a perfect circle zone that are some n units from the point feature Line buffering; buffering around a line creates a zone that has the approximate shape as the original linear feature extended out n units from the original linear feature Area/ polygon buffering; buffering around an area creates a zone that has the approximate shape as the original polygon feature extended out n units from thew original polygon feature Variable buffering; the buffer distance or buffer size can vary according to numerical values provided in the vector layer attribute table for each feature

Answer 59

1.Arbitrary -Best guess by a GIS analyst of what the size of a buffer should be; not based on scientific principle 2. Causative -Landscapes or conditions surrounding points, lines, and areas are not heterogenous -If a priori (before the fact) about these conditions, then you can apply causative bugger logic to identify what the buffer distances should be for each 3.Mandated Agencies set strict guidelines and restrictions for buffer dimensions around features

Answer 60

-An overlay of two or more thematic features can be performed using either vector (topological) or raster (logic) layers -Topological overlay involves comparing 2 or more vector feature layers that have been topologically structured to produce a new topologically structured vector feature layer -Basically, new layer combines the attributes and geometric characteristics of the 2 initial input layers

Answer 61

**see visual representation 1. intersection; uses AND 2. union; uses OR 3. symmetrical difference; uses XOR 4. Identify; computes geometric intersection of the input layer and te identify layer = the input feature will get the attributes of the identity layer 5. clipping; none of the attributes are combined 6. erasing; none of the attributes are combined 7. splitting

Answer 62

1. Overlay of a point layer on a polygon layer= point in polygon overlay 2.Overlay of a polygon layer on a polygon layer= polygon in polygon overlay

Answer 63

**view example 1.Shows step by step approach to how GIS analysis was conducted 2.Automates the process 3.Makes it shareable 4.Makes it transferable and interoperable

Answer 64

The process of taking input cell values and replacing them with new output cells. Change cells value or meaning by applying this technique. Simply or reinterpret cell value.

Answer 65

-To determine the euclidean distance (as the crow flies) between the two centroids of two pixels (cells) in a raster, you would use Pythagorean theorem -This uses the Euclidean algorithm and simply searches a specific distance away from a point, line, or area and recodes all of those pixels into a user specified value (distance value = 100m) -Point Euclidean, line Euclidean, area (polygon) Euclidean

Answer 66

Where each pixel (cell) at a location in a raster dataset may be considered a local object. The value of this pixel can be operated upon, independent of neighbouring pixels (basically changing the value of a cell) 1. Arithmetic 2. Logarithmic 3. Trigonometric 4. Power functions (integer, sin, log10, ^2)

Answer 67

Map algebra: tomlin; a suite of arithmetical and algebraic operations/functions Take two raster with two different (multiple) values and combine them 1. Simple math operations (min, max, mean, std dev) 2. Simple math operation; ranking (summation) 3. Simple math operations; frequencies (majority, minority, diversity)

Answer 68

- basically adding a bunch of layers to create a sandwich -Extent is the same between each layer -Each cell is the same value? -The cell between each layer line up to the next layer must line up or else overlay will not work -Raster is not just cell on top of cell -Resolution MUST be consistent between each layer

Answer 69

RUSLE -revised universal soil loss equation; determines the long term average annual soil loss in tons per acre per year for a geographic area (if erosion occurs what is the restoration factors you will put into place? Map tells you where and possibly how you can)

Answer 70

1. Shape -Local raster operation modifies the values of each cell in a raster layer, while neighborhood operations are dependent of the characteristics of neighboring cells -So, cell (f) values change due to the cells surrounding it -Uses a spatial filter (3x3 or 5x5 most common) 2. Filter -Value of the output cell is a function of the logic applied to the cells in the n x n spoatial moving window. Can fill in missing values, as spatial window moves it recalculates all values.

Answer 71

1. Qualitative operation; land cover (majority, minority, diversity/unique values) 2. Quantitative operations; elevation (minimum, mean, max, std dev)

Answer 72

1. Zonal mean; the max elevation value in each zone is assigned to all the pixels in the zone 2. Zonal minimum: the minimum elevation value in each zone is assigned to all the pixels in the zone

Answer 73

-Use netwrks to move goods, resources, serivces, and themselves from place to place - Even other species rely on them to migrate form habitat to habitat or landscape to landscape -A system of topologically interconnected lines and intersections that represent a linear network of possible routes from one location to another used: 1. Optimum paths or pathways 2. Locating resources or facilities within a network

Answer 74

-Process of finding a geographic location from an address or a postal code -Process of transforming a description of a location to a location ont he earths surface -Most common type is address matching main componants 1. Input dataset; records of addresses 2. Output dataset; resulting addressed locations that are geographically referenced, can be impacted if input data is not quality assured 3. Processing algorithm; determines the appropriate position of the input postion in the output dataset. This is based on the attribute data in the reference dataset 4. Reference dataset; has all the geographically referenced information to aid in finding the correct locations of your input dataset

Answer 75

-Plots addresses as points on a map -Addresses are processed along road segemnts based on attrbitues in a geocoded database -results are also shown as a % of those addresses succesfully matched = match rate

Answer 76

1.Misspellings 2.Incorrect city names 3.Wrong direction 4.House numbers out of street range 5.Wrong street type 6.Abbreviations 7.Missing data 8 Must specify the network analysis to be performed ex straight line

Answer 77

1. Undirected -Transportation based -Movement along traversed lines (edges) n any direction -Instances of one-way, U turns are permissible -Fastest or shortest route applications 2. directed -Movement of services or materials in one direction within a network -AKA geometric utility

Answer 78

*see diagram 1. collect source network information -GPS, digitization 2. Build topologically correct Network dataset elements -edges (dervied from lines ex one way, length, x and y), -junctions (derived from -intersections, complete stop, 4 way, barriers), turns (right, left, yield) 3. specify network analysis -identify optimum route, find closest facility, identify service area and optimum delivery route and then location-allocation modelling 4. Solve the network analysis problem and present results -cartographic display, route instruction (turn by turn) *network layer defines elements and the connectivity gives values to the element attributes

Answer 79

1. shortest path or optimal route -Uses impedances or cost to move from one location to another 2. Network service area analysis -Geographic region that encases all parts of the network that can be reached within a certain impedance (cost) 3. Location allocation modelling for facility location -Finding best locations for on more facilities that services a given set of points (customers) -Take factors such as facilities available, cost and max impedance times

exam 1 ans 2 Flashcards

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