Terminology Flashcards
Certification
A process, often voluntary, by which individuals who have demonstrated a level of expertise in the profession are identified to the public and other stakeholders by a third party. Designed to recognize expertise. -GISCI
Deontology
Treat others with respect, and not as a means to an end.
Virtue ethics
View highly moral people as a personal guide or role model
Utilitarianism
Do the most good for the most people.
Kantianism
Follow maxims of conduct that anyone could follow or adopt.
HIPAA
Health insurance portability and accountability act; for the GISP, you must never expose an individuals health records or reveal their address. You can generalize the data so as to not reveal discrete info.
Data dictionary
Not a part of a software, and is often stored in a largely accessible system; describes the content of your data model; you can put codes, units of measurement, coordinate system, update frequency and data sources.
Open Geospatial Consortium (OGC)
International industry consortium of over 526 companies that develop interface standards; FAIR: findable, accessible, interoperable and reusable location info and services.
Geopackage
.gpkg extension; based on SQLLite, it’s an open format supported by OGC that supports vector and raster data.
Federal Geographic Data Committee (FGDC)
Chaired by the secretary of the Interior, it is an org. Of US Federal geospatial professionals that focus on providing executive, managerial, and advisory direction and oversight for geospatial decisions and initiatives across the federal government.
National Map Accuracy Standards (NMAS)
Overseen by the Federal Bureau of Budget; says that 90% of at least 20 points need to have a horizontal accuracy of either 1/30” for >1:20,000 (ie. Large scale, small area), 1/50” for <= 1:20,000 (ie. Small scale, large area), or a vertical accuracy of 1/2 the contour interval.
Geomorphology
Study of earth’s physical features and their relation to its geologic structures.
Divergent boundaries
Ocean ridge spreading
Convergent boundaries
Plates pushing together
Transform boundaries
Plates sliding past each other
DOQQ
Digital other ortho quad; old aerial file type; USGS
DLG
Digital line graph; old vector file type used by USGS
Root Means Square Error (RMSE)
The average of the distances between the mapped location and the actual location (distance in x and y)
RMSE = √(x1-x2)^2+(y1-y2)^2
Relationship between RMSE and NMAS
Measure the RMSE of 20 points, then compare those values to the NMAS for your map and see if the RMSE is less than or equal to the standard (both accurate and precise). If it is then your map is compliant with NMAS
Accurate
Attributes and features match the real-world data and locations.
Precise
Measurements are replicatable and come close to each other.
Raster Accuracies
Spatial, Spectral and Classification
Vector Accuracies
Spatial and attribute
Fuzzy Tolerance
an extremely small distance used to resolve inexact intersection locations due to a limited arithmetic precision of computers; usually digitizer precision uses a constant of 0.002”
Tenets of Spatial Data Transfer Standard (SDTS)
- Accuracy testing should be performed against an independent source of higher accuracy, such as survey or GPS coordinates
- Compare well known and easily identifiable locations on the raster to known locations on the ground and compute an RMSE
- Raster accuracy should be reported at 95% confidence level
- 20 points minimum should be tested, and should be distributed across the raster area
Pixel
A pixel is a cell, but not all cells are pixels. Pixels have records of a reflected value, used in remotely sensed imagery to identify ground cover or buildings/objects.
Confusion Matrix
A statistical method used to determine the land classification accuracy of a raster-derived classification layer; also called an Error Matrix
Kappa Coefficient
Similar to confusion matrix, a statistical measurement of how the land classification layer lines up with the ground truth; 0 is no agreement, and 1 is complete agreement.
Ground-truthing
Used in error or confusion matrices; Process of taking a set of random areas, called sample classes, and going out into the field to check to see if the land classification layer is accurate and precise compared to the “truth on the ground”.
4 kinds of raster resolution and accuracy
Spectral: are cell values the proper value?
Temporal: Does the raster accurately represent conditions for the time period claimed?
Spatial: is the raster in the proper location and does the cell size accurately represent the area modeled?
Radiometric: Are various features distinguishable from each other? Greater bit depth=higher resolution
CSDGM
Content Standard for Digital Geospatial Metadata; this is the standard created by the FGDC
ISO
International metadata standard endorsed by the FGDC; makes mandatory certain metadata fields, such as Title, Date, Geographic location, Language, Topic Category, Abstract and metadata. Also includes domains and their values.
Geoid
Surface of the earth’s gravity field; wide at the equator, and the pull of gravity is stronger over mountains. Geoid is the earth at 0 elevation
Spheroid (ellipsoid)
The approximate shape of the geoid as a mathematical model; bulges a little around the equatorial region, like the geoid
WGS84
GCS WGS84 is used by GPS units and is the globally preferred spheroid; SRID 4326
Geomatics
The mathematics of the Earth; is an umbrella term for every method and tool used for gathering, storing, processing, and delivering geographic information.
Geographic Coordinate System (GCS)
Used to define locations on the earth/3d surfaces as well as flat, 2d surfaces using grids; made up of Lats, Longs, Extents, the Prime meridian, international date line, the equator, and hemispheres
Datum
Mathematical model related to real world features; are used to shift the spheroid a bit so that it fits part of the earth really well
Control Points
Brass or aluminum survey points installed in the ground by the USGS in the US as well as internationally where the location is calculated to create a reference grid.
Datum Shift
The error of change you see by overlaying features represented in different datums.
NADCON
North American Datum Conversion Software; created by National Geodetic Survey; converts between NAD27 and 83
HARN
High Accuracy Reference Networks; US State Plane Coordinate Systems have been calculated in HARN; incorporates highly accurate measures of elevation
ITRF
International Terrestrial Reference Frame; determined by the intl association of geodesy (IAG) which updates it when tectonic plates move; not based on a spheroid, but upon very sophisticated calculations that come out to about the same as a spheroid-based datum.
Planimetric
Independent of elevation; represented on 2D maps as seen from the air. They contain no relief or elevation representation and are often digitized from ortho-rectified imagery.
Central Meridian
Centers your coordinate system on the area of the globe that you want to be the most accurate (line of longitude)
Universal Transverse Mercator (UTM)
A cylindrical projection that preserves direction and is rotated horizontally; is very useful around the equator; parallels and meridians are at right angles, and are 6 degrees wide, 60 longitude “slices”; typically in meters
Robinson Projection
Used for whole world maps, however it distorts shape; better for mapping higher latitudes
Lambert Azimuthal Equal Area
An azimuth maintains direction and area; lambert conformal conic projections are used for areas that are broader in the E-W range
WGS84 Web Mercator
Used by base maps and web maps; tries to preserve shape, but not area; SRID 3857
SRID/EPSG
Spatial Reference Identifier; Used by OGC
Georeference
Any data tied to real-world coordinates
Euclidean Distance
Bee-line distance, computed using the Pythagorean Theorem.
C = sqrt (a2 + b2)
Manhattan Distance
Sum of the length of the edges
Loxodromic
A line of constant bearing
North Azimuth Direction
Angle is clockwise from N
South Azimuth Direction
Angle is clockwise from S
Polar Azimuth Direction
Angle is counterclockwise from the positive X-axis (E)
Quadrant Bearing Direction
Specify N or S, the angle and the direction; ie. S15E or N45W
Angle of Deflection
Measured as a positive or negative angle away from the previous line
Typography
Process of putting text on a map, such as Labels, annotation, layout text; never use more than 2 font families on a single map
Color Formats and Qualities
RGB, CMYK, HSV
RGB: most common, each color has a value from 0-255
HSV: stands for hue, saturation and value; hue ranges from 0-360 and defines base color; saturation defines lightness and darkness (1-100%); value defines the color intensity (1-100%)
CMYK: all 4 colors are defined as a percentage (1-100%)
Multivariate
Defined literally as “many variables”, describes a map or display that has more than one layer displayed, or overlayed on one another.
Thematic Map
A map that is symbolized by a particular theme, rather than simply showing locations. ie. “Type of Ecosystems” map showing ecological system areas symbolized by type.
Jenks Natural Breaks
Data naturally falls into classes
Quantile class breaks
Equal number of features per class
Equal interval class breaks
Equal range of values in each class
Defined interval class breaks
Fixed interval where values are forced into breaks
Standard deviation class breaks
Classes are defined by how far above and below the mean values are
Geometric Series class breaks
Classes are defined by geometric series
Contours
Lines of equal value, whether it be elevation or depth; measures of air pollution, rainfall and noise are isolines; index contours are the thicker bold lines at set intervals that help with reading contours; supplemental lines are approximated values around flatter areas; intermediate lines are regular and thinner, typically unlabeled
Nodes
The ends of lines
Vertices
A vertex is singular; a point along a line that defines the shape of the line or the outline of a polygon
Pseudo-node
Nodes that appear connected, but are only overlapping so as to represent a change in line attribute (linear referencing system)
Dangling node
end of a node that doesn’t meet up with any other feature; is sometimes a geometry error, but can also be valid, such as cul-de-sacs in a roadway network
Intersection (geometry)
Where two or more lines cross, not necessarily an error (think overpasses and underpasses)
Centroid
The center of a feature’s weight
Shapefile
Store non-topological geometry; no annotation, domains, subtypes, or topology rules; not an OGC standard but an industry standard; required files are .shp, .shx, .dbf and ideally .prj
Geodatabase
Object-oriented database; relational; can hold vector and raster but not both; topology rules and networks; personal (mdb) can hold 2GB, file gdb can hold 4GB default or more, and SDE rdbms can hold as much as your server allows
KML & KMZ
Keyhole Markup Language; kmz is zipped kml; an OGC standard file type that holds 2D and 3D features in an XML language
DXF, DWG, DGN
AutoCAD and Microstation file types
Triangulated Irregular Network (TIN)
Based upon Delaunay triangulation, also called wire frame model, based upon vector points to create highly sophisticated surfaces with optimal storage.
ASCII files
Txt, dat, csv
Digital Elevation Model (DEM)
USGS files showing elevation, part of the National Elevation Dataset; represent 1:24000 scale bare earth maps; have been replaced by 3DEP LiDAR as the new standard for elevation
XML and GML
geography markup language; both are OGC standards for storing objects; gml is for custom features, kml and xml is for points lines and polygons
Spatial Data Transfer Standard (SDTS)
Published by ANSI, transfer data and metadata without loss; NOT an FGDC standard anymore
Differential Correction
Using a base station or reference station, taking multiple measures from a gps unit in the same place and being able to measure by how much each coordinate is off from the reference point.
Virtual Reference Station (VRS)
A network of reference stations that monitor GPS signals and log corrections in real time or during post-processing; is a paid or a free subscription service, one such example is CORS from NOAA
Real Time Kinematic (RTK)
A type of differential correction that occurs in real time using a rover and base station and a digital connection, usually a cellular network.
Satellite-Based Augmentation System (SBAS)
Satellites that send differential correction signals from ground stations to GPS receivers via satellites. Examples include WAAS in North America developed by the FAA, and the private company OmniStar
Geodatabase Topology
A model of the relationships that exist among eatures in a geodatabase; stores the properties of the topology with the data; defines rules on relationships among features; gives priority to features of greater accuracy; can only be applied to feature datasets; form of QC because it does not prevent you from making errors
Topology Rules
Must not overlap; Must not have gaps; Must be larger than cluster tolerance, must not self-overlap; contains point…
COGO
Coordinate Geometry; allows you to enter metes and bounds in order to develop a line or polygon.
Control Points
Locations on the unreferenced dataset that have exact matches on the referenced dataset/that you know the coordinates for and can type in
World File
Used to store georeferencing info; often have an extension ending in w like .tfw; either stored as the header of an image file, as a separate ASCII world file, or in the row/column info of the image; support affine (1st order polynomial) transformations
Field Data Collection Process
Planning: Get the right tools, set up schema and domains, decide on rules and methods
Collection: Collect data in a sample area: similar to the pilot study
QC: Check the accuracy of collected data, then go through steps 1-3 again if needed
Finish: Collect remainder of data
PDOP
Positional Dilution of Precision; describes how good the satellite configuration is for collecting accurate points; a low PDOP is better. Values below 6 are okay, but values below 4 are great
GPS Signal Frequencies
L1 mapping grade and L2 survey grade; satellites transmit on the same frequencies, however receivers use Code Division Multiple Access (CDMA) to separate signals out into channels
Signal-Noise Ratio (SNR)
Signal strength/Noise Level (lower values are better); similar to PDOP in determining accuracy of data collected
Unmanned Aerial Vehicle (UAV)
In essence, a drone; the entire system is known as UAS
Theodalite
A precision tool used to measure angles both horizontally and vertically; more accurate than transits; a total station is a theodalite plus a digital range finder.
Geomatics
The mathematics of the Earth, including gathering, storing, processing and delivering geographic information
Buffer
Creates a new polygon feature class from an input layer and buffer distance; input can be any geometry type
Clip
Extracts data from one feature class using polygons from another feature class. Attributes of the input FC/target are maintained
Union
Combines all features and attributes of 2+ feature classes. Can split features when necessary.
Intersect
Combines all features and all attributes of 2+ feature classes, but only in area common to both/all.
Spatial join
Joins attributes from one feature class to what may be an unrelated feature class (meaning there is no primary key, but only overlapping geometry)
Table Join
Joins attributes from a feature class or table with another feature class using a primary key and foreign key
Append
Adding geometry and attributes from another feature class into an existing one
Merge
Adding geometry and attributes from 2+ feature classes into a new feature class
Overlay Analysis
Works using boolean logic to return true/false values; can be done on rasters
PEMDAS
Acronym used to remember Order of Operations in mathematics; stands for Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction
Radians
2 radians = 360°
1 radian = 180°
1 radian/2 = 90°
1 radian/4 = 45°
Conversion factors
1 ft = 0.3048m 1 m = 3.28084 ft 1 mi = 5280 ft 1 mi = 1.60934 km 1 km = 0.621371 mi 1 acre = 43,560 ft2 1 mi2 = 640 acres
Tobler’s First Law of Geography
“Everything is related to everything else, but near things are more related than distant things.”; Described numerically with autocorrelation
Moran’s Index
Measure of spatial autocorrelation; Positive means that similar values are clustered together spatially; negative means dissimilar values are clustered together spatially; zero means that there is no spatial autocorrelation.
Correlation Coefficient
Ranges from -1-1, with 0 being no correlation
R-Squared
Coefficient of determination statistical equation; is the square of the correlation coefficient; gives you the percentage of variation that is explained by your model (how well does X explain the variation of Y?)
Oblique Imagery
Taken at an angle so you can see angles/heights of buildings and other structures
Normalized Difference Vegetation Index (NVDI)
A measure of the state of plant health; actively growing, healthy vegetation reflects lots of IR, whereas sick or dying vegetation reflects very little; values range from -1 - 1 where values of 0.2 - 0.5 is moderate health
Raster Classification
Can either be supervised or Unsupervised; basically, different ground surfaces reflect RGB and IR in different ways, so you can take those values and group them into classes, creating a landcover raster (discrete)
Light Detection And Ranging (LiDAR)
Laser-derived data; vector point clouds that are often used to interpolate raster surfaces; the first return is what bounces off of buildings and vegetation, basically anything covering earth’s surface, and the second return gives us bare earth surface values; LiDAR point clouds are stored as .las files
Unsigned 8-bit vs signed 8-bit rasters
Unsigned can hold 256 values; signed can hold between -128 - 127
BIL, BIP, BSQ
file types for raster storage
LZ77
LZ77 is run length encoding, the lossless method for compressing rasters; this basically only stores the cells with values
Spline
maintains measured values during a raster surface creation/interpolation process
IDW
Inverse Distance Weighted; weighted averages surrounding known values; cases smoother raster interpolation: points that are X cells away have 1/X the amount of influence over your missing cell value. So, the further away the points are, the less influence they have over your interpolated value.
Kriging
Kriging uses known points, fits an equation to them that would best represent the dataset, and creates a slope surface using interpolation. NOTE: This is only useful if your surface is relatively constant.
Map Algebra
Allows for execution of all Spatial Analyst tools, operators, functions and analyses on rasters;
can overlay and combine rasters, as well as manipulate them on a cell-by-cell basis; Raster Calculator is the tool used for Map Algebra.
Relational Database
A data structure in which collections of tables are logically associated with each other by shared fields; allows joins, relates and relationship classes
Object-relational Database
Feature classes, rasters, tables; each FC has an attribute table; there can be joined tables, relationship classes, topology rules and network classes
Views
A temporary subset of a table, yet if you make a change through a view, you change the original
Index
A data storage structure that speeds up retrieval time of data at the extent of extra space and writes
Trigger
Code that gets executed as the result of an action on a table
Function
A bit of code that performs a particular action
Schema
The structure of a database; can be based upon a model, such as PODS, APDM, UPDM, PPDM, LGIM
Short Integer
-32,768 to 32,767; Can be positive or negative, but must be whole numbers
Long Integer
-2,147,483, 648 to 2,147,483,647; Can be positive or negative, but must be whole numbers
Float
Single Precision; -3.4E38 to 1.2E38; can be decimals with up to 7 digits of accuracy, 6 if you’re in the negatives
Double
Double Precision; -2.2E308 to 1.8E308; can be decimals with up to 15 digits of accuracy, 14 if you’re in the negatives
BLOB
Binary Large Object; stores the shape/geometry (object) or can store images, videos, coordinates, word documents and other files in a single field.
GUID
Global Unique Identifier
Key Field
Field common to two or more tables where relationships can be established; Foreign Key and Primary Key
Relationship Class
A permanent connection between items in a geodatabase; uses key fields
Composite Relationship
One feature is a component of another, so if the first feature is deleted or updated, then other components must also undergo similar change
Simple Relationship
One feature is not dependent upon another for existence, however they are related.
Archive
A library of your historic GIS data; write protected, makes important historical data easy to find; sorted by last used date
Retrieval
Process of going back into archives to search for data by owner, project name, size, date saved
System Replication
Used as a live backup, running along side the production system in case Prod fails or otherwise goes offline
Database Role
A group of permissions assigned to users on a database
Scripting
Scripts are programs written in a scripting language that does not have to be compiled (ex: create a python script that does x)
Programming
Creating compiled tools and software
Software Engineering
Design, development, and implementation of software
API
Application Programming Interface; gives programmers access to components of their software, data, or service
IoT
the Internet of Things; explains the connection between many devices that are internet enabled, that can access and contribute data and information, as well as perform analytics and live reporting.
Ports
In essence, “doors” between the firewall and your organization, where only those who know about the door can gain access, but access is secured.
Firewall
Used to secure ports and programs from those that try to gain unauthorized access.
