REN R 201 Midterm 1 Flashcards

Geomatics

The science of dealing with systems/technology that collect, store, and applying georeferenced data using a variety of different measurement tools

Georeferenced data

A specific spatial location that is tied to a set of coordinates

What are the 7 tools that make up Geomatics as its components?

• Global Navigation Satellite Systems

• Photogrammetry

• Geodesy and land surveying

• Geographic information systems (GIS)

• Cartography

• Remote sensing

• Hydrography

Geographic Information System (GIS):

A system that collects, stores and visualizes data to answer spatial relationship questions by representing real world entities

What are Geographics? What are some examples?

• Deals with geographical or spatial features

  • Physical: Eg forest, soil areas, road networks, hydrology

  • Cultural: Census areas

  • Economic: Economic sectors (such as trade flow)

What is Information in GIS?

• Information includes vast data-sets with attributes (Characteristics), including non-spatial information such as classifying road types, forest species, etc

  • Data is plugged into software and the output is information

What are Systems in GIS?

Refers to technology, including software to visualize spatial data and the hardware it runs on

GIS Maps

• Digital representation of spatial data with separated layers showing information, offering insight into patterns, trends and relationships

  • Data is overlaid to show patterns

What does GIS allow us to do?

• Use spatial and non-spatial information together

• Lets us access records tied to geographic positions

• Allows us to manipulate and show knowledge in new ways

• Provides a set of framework for analyzing geographic data

What are the 5 components of GIS?

• People: Anybody who is using GIS (experts, consumers, analysts, etc)

• Software: The programme application that performs the function

• Hardware: Computer that GIS operates on

• Data: The information collected 

• Methods: The guidelines, standards, and procedures which change depending on the question being asked

Provide 3 examples of things we can do with GIS

• Finding and identifying geographic features

• Measuring geographic features

• Characterizing spatial distributions: Revealing patterns by grouping features, and narrowing down these features to create clear patterns

• Work with networks: Ie routing a bus network to reach the maximum amount of people

• Summarize geographic data

• Compare different map layers

• Run surface analysis

What does data analysis in GIS help us do?

makes us more efficient through communication, decision making, recordkeeping, etc

What are four Industries that use GIS to maximize the efficiency of their systems?

• Natural resource management (Forest management, wildlife conservation, soil mapping, etc)

• Agriculture (Precision farming, crop yield prediction, water stress, etc)

• Forestry (Forest inventory, tracking deforestation, forest fire management, etc)

• Ecology (Migration patterns, habitat stability, species biodiversity, etc)

What laid the basis for GIS and when?

14th century: Static maps and manual cartography lay the basis for GIS

What did John Snow do in 1854?

John Snow performs early spatial analysis to track the source of a Cholera outbreak in London to a contaminated water pump

What did the 20th century do to GIS?

The digital revolution allowed GIS to be applied to working fields

When was Canada’s Geographic Information System created? And Why? When did it become fully operational

1963: Development of Canada’s Geographic Information System (CGIS) to analyze Canada’s natural resources land inventory is created by Roger Tomlinson (the father of GIS, and the person who coined the name)

1971

What did Harvard establish in 1965?

Computer Graphic and Spatial Analysis lab

Who were the founders of the Environmental Systems Research Institute (ESRI) and when was it founded?

Established 1969 by Laura and Jack Dangermond

When was ERDAS founded?

1978

What did ESRI launch in the early 1980s?

ESRI launched ARC/INFO (software system) which integrated a standard relational database management system (INFO) to handle objects stored as arcs (ARC) with a command driven Toolbox

What were 4 key events that helped GIS’ popularity in the 1980s?

• GIS received a tech boom, with several other companies launching their own systems during this decade

• The Global position system (GPS) became operational

• A shift from mainframes to desktops and personal computers, increased analytic capabilities, a shift from government to large corporations and small companies, and academic communities involvement in the tech increased the boom

• GIS technologies were difficult to incorporate and resulted in a high failure rate for those adopting it

What are 3 things that affected GIS in the 1990s?

• Remote sensing, image analysis, and scanning technologies are integrated into GIS making it an integral part of any organization that uses maps

• Canada is the #1 country in developing GIS

• Remote sensing, AI, and scanning technologies are integrated into GIS, with Canada leading the development

Canadian Geographic Information System (CGIS)

First fully operational GIS model in the world, created to analyze data from the Canada Land Inventory (CLI) to inform the development and management of rural areas

What did CGIS innovations include (name 3)

• Using scanning to input high density areas/objects

• Vectorization of scanned images (vectorization is turning an image into a set of instructions for a computer on how to reproduce this image)

• Turning data into map sheets or tiles, matching edges across the tile boundaries

• Separating data into themed layers

• Standardizing a system to create absolute coordinates, allowing every one to know precisely where something is

• Coding boundaries of area objects

• Separating data into attributes (nonspatial) and locational (spatial) files

Synteny Mapping and Analysis Program (SYMAP)

• Landscape planning study developed by Harvard in the 60s 

  • (Harvard Laboratory for Computer Graphic and Spatial Analysis also developed other computer mapping programs)

What are the 5 GIS functional Elements?

• Data acquisition

• Preprocessing

• Data Managements

• Manipulation and Analysis

• Project Generation

What is Data acquisition in GIS Functional Elements?

Identifying and gathering the required data from a variety of different sources

What is Preprocessing in GIS functional Elements?

Manipulating the data for the GIS analysis or visualization (putting it into the GIS, exploring, converting the file as necessary, checking the quality)

What is Data management in GIS functional elements?

Organizing the data into a database

What is Manipulation and analysis in GIS functional elements?

Giving GIS instructions on how to generate the specific output

What is Project Generation in GIS functional Elements?

Deriving outputs from the GIS (stat reports, maps, charts, etc)

What are the 2 Data types in GIS?

• Spatial data: Describes the absolute and relative location of geographic features using vector or raster models 

• Attribute/non-spatial data: Describes the quantitative or qualitative characters of the spatial features

What are the two data models for spatial data in GIS?

Vector Data and Raster Data

Vector Data and it’s type of data

• Vector Data: Represents Geographic data using points, lines or polygons, and is used to show discrete and well-defined features (eg: roads, buildings, and land parcels)

  • Discrete features: Data with distinct start and end points

Raster data and it’s type of data?

• Raster data: Represents geographic features as grid cells, with each cell having a value and is used for continuous data (eg: temperature, elevation, precipitation)

  • Continuous data: Data where values fall along a number line and can have any value

  • Grid system misses portions of information shown in Vector

How is Vector data shown in GIS?

• Points: A location defined by a specific set of X, Y coordinates

• Line: Two or more points with a straight line connecting them

• Polygon: A set of points connected by lines that form a closed shape

Which areas is Raster data best for? Which areas does it struggle in?

Best for: temperature, elevation, aerial images, soil type, etc

Struggles with things that have a clear boundary (eg: a lake)

Spatial resolution

• The size of the grid cell/pixel used in the analysis in Raster Data

  • Changing the cell size comes with trade offs

What are the pros and cons of Smaller or Larger resolution?

Smaller:

• Higher resolution

• Higher feature spatial accuracy

• Slower display

• Slower processing

• Larger file size

Larger:

• Lower resolution

• Lower feature spatial accuracy

• Faster display

• Faster processing

• Smaller file size

Raster Tiles

• Raster tiling divides large datasets into smaller, manageable pieces 

  • Tiles make it easier to upload and download things, going piece by piece rather than all at once

Raster Tessellation

The tiling of a surface using one geometric shape of tiles, with no overlaps and no gaps (usually Hexagon, square, or triangle)

Shapefiles (.shp)

•  GIS file extension which is a collection of files and not just a single file, and can represent points, lines, or polygons

  • Cons: Take up a lot of storage, Dbase file format for storage which has a 10 character limitation

  • Usually shared as a .zip file and then is unzipped

What are the 3 most important file extensions used with ArcGIS for vector data?

.shp: Shape file

.shx: Index format for the feature geometry

.dbf: File geodatabase, feature attribute information in dBASE IV format

What is a Geodatabase? What are feature datasets and feature classes?

• Collection of geographic datasets of various types that are held in a common file system folder

  • Feature datasets: A collection container of feature classes (aka classes that share a spatial reference)

  • Feature class: A homogeneous collection of common vector features (lines, points, polygons) as well as annotations

What are the 2 main things that must be obeyed when naming Folders for ArcGIS?

• Note: Folder names should not include spaces, special characters, or start with numbers

• Note: Use _ to separate words in names

What does the contents pane allow you to do in ArcGIS?

lets you visualize all your data, by arranging the layer names

Queries:

• A tool used to search for and a select a subset of features and table records 

  • Queries are questions posed to a database

What are the types of searches and queries that can be done in ArcGIS?

• 1. Selection

• 2. Query by attribute

• 3. Query by geography (location or spatial query)

Select by location

• Allows you to highlight a particular feature by examining their position relative to that feature

  • Eg: “Pipelines completely within Caribou Range”

Spatial relation (include contains and covers)

• Tells the software what spatial relations we want

  • Contains means that the desired feature has to be entirely within the boundary 

  • Covers means that the desired feature must be inside the boundary, but can be touching the boundary

Structured Query Language (SQL)

Computer language developed to query attribute data by implementing clauses to structure the database queries

Clause

A language element that include select, from, where, order by, and having query statements, with “select” and “from” queries being mandatory

What are the meanings of the clauses select, from, where, order by, and having?

• Select: What attribute table field you want to see

• From: Where in the attribute table the information is

• Where: User-defined criteria for the information that has to be met in order for it to be included in the output set

• Order by: denotes the sequence in which the output set will be displayed

• Having: Used to filter output from the Order by clause

• Select and from clauses are mandatory, the rest are optional

What are the 3 operators that can be included in SQL?

• Relational: Employs statements like equal to (=), greater than (<), less than or equal to (>=)

• Arithmetic: Include mathematical functions (addition, subtraction, etc)

• Boolean (usually only appears inside a WHERE clause): Include the statements AND, OR, XOR (exclusive or), and NOT

  • AND: Selects records that match at least one condition

  • Or: Selects records that match both conditions

  • XOR: Selects records that match only one condition

  • NOT: Selects records that don’t match the expression

SQL Null Values:

Values that haven’t been specified or entered, and are always preceded by IS or IS NOT

Cardinality

• Describes the relationship between records in one table (the destination) and records in another (the origin) by using a common field

  • Database relationships are defined by cardinality describing the numerical association between records in two tables

What are the 4 types of cardinality?

• One-to-one (1:1): A single record in one table relates to a single record in another table

  • Eg: Each province has one capital city

• One-to-many (1:n): A single record in one table relates to multiple records in another table

  • Eg: One province can link to many cities

• Many-to-one (n:1): Inverse of one-to-many

  • Eg: Types of birds that visit a forest

• Many-to-many (n:m): Multiple records in one table, relate to multiple records in another table

Table join

Combines 2 fields based on the value fields that can be found in both tables

What does Multi-Criteria Vector Overlay do?

plugs into multiple different data sets with multiple different variables and finds the point where everything we want is available

What is topological overlay and derived spatial information?

• Merges spatial geometry and attribute records into a united layer

  • Derived spatial information: Creates new geometric boundaries (intersections) and resulting in an output feature

What are the 3 main tool categories in ArcGIS?

Extract toolset: Allows us to subset data without altering the associated attributes

Overlay toolset: Combines boundaries and joins attribute tables

Proximity toolset: Evaluates distance and neighborhood relations

What are the 3 extract tools?

• Clip: Cookie-cutter spatial extraction

• Select: SQL logical filtering (filtering out what we don’t want)

• Split: Subdividing layers

What are the 3 overlay tools?

• Intersect: A shared overlap

• Union: Complete combination

• Erase: Removing boundaries

What are the 3 proximity tools?

• Buffer: Zone set up based on the distance of the influence

• Near table: Point-distance metrics

• Thiessen: Voronoi proximal areas

What are the 2 types of Clip operations?

• Spatial extent trimming: Cuts out input features to the exact boundary of the clip, like a cookie-cutter

• Attribute table invariant: The output layer will only inherit attributes from the input dataset, attributes from the outside of the cookie cutter will simply be removed

What are the 3 clipping types?

• Polygon input: Polygons are clipped at the exact boundary of the clip feature

• Line input: Line segments outside the clip polygon or non-intersecting lines are removed (applicable with lines and polygons)

• Point input: Only point features inside the clip boundary are copied (applicable with only point, line, or polygons)

What are the 3 select tools?

• SQL logical filtering: Filters and removes data we don’t want based on attribute expressions (eg: “ZONING” = “PARK”)

• Output Generation: Outputs a new feature class that only has matching features to the filtering, retaining all the original attributes

• Split tool: Separates the data into smaller pieces

What are the two subdivisions of the split tool?

• Zonal Subdivision: Splits an input layer using split polygons to create individual dataset outputs for each zone (similar to making tiles, smaller size makes them easier to study) 

• Batch data division: A useful tool for dividing regional datasets into municipal or administrative management tiles

What is overlay analysis? What are the two types?

• “What’s on Top of What?” 

  • Fundamental spatial questions: Answering questions that can be answered by overlaying different data layers (eg: housing with floodplains)

  • Derived relationships: Overlay operations that create new vector geometrics and merge the relevant attribute records

What are the 6 overlay tools?

Erase

Identity

Intersect

Symmetrical difference

Union

Update

What is the Erase overlay tool? What are the 2 types?

• Remove features overlapping the erase boundaries

  • Spatial subtraction: Removes features or portions of features in the input layer that overlap the erase polygons

  • Exclusion mapping: Used to subtract restricted zones, waterbodies, or existing urban areas from potential candidate sights

What is the identity overlay toolset? What are the 2 types?

• Keep all input features, joining identity attributes

  • Input geometry preservation: Creating a geometric intersection, where everything outside of this intersection is removed

  • Selective attribute transfer: Portions of input features overlapping identity features inherit identity attributes, non-overlapping regions receive nulls

What is the intersect overlay tool? What are the 2 subtools?

• Preservers only the overlapping areas across layers

  • Shared extent extraction: Preserves only the features that overlap across all input layers (only want the “AND” part of the venn diagram)

  • Attribute combination: Combines input layers attribute tables from all participating layers into an output feature class

What is the symmetrical difference overlay tool? What are the two subtools?

• Retains areas that don’t overlap

  • Exclusive Extent Extraction: Returns features or portions of features in the input and update layers that do not overlap

  • XOR: Removes common overlapping regions completely

What is the union overlay tool? What are the 2 subsets?

• Combines all geometries and attribute tables

  • Complete geometric union: Combines all geometrics from input layers into a single output layer

  • All-inclusive attributes: Preserves all unique overlapping boundaries and attaches attribute values for every participating layer

What is the udpate overlay tool? What are the two subsets?

• Replaces input geometry with update features (eg: updating layer from having the wrong road shown to the correct road shown)

  • Geometry replacement: Calculates geometric intersection, replacing input features with updated polygon geometries

  • Attribute revision: Updates attribute tables and geometric boundaries using revised spatial boundaries

What are the 3 overlay topological errors?

• Undershoots: Vector lines that should touch fail to connect (creates gaps in the network), these can be super tiny and hard to notice

• Overshoots: Vector lines extend beyond the intended intersection point

• Sliver polygons: Tiny, spurious polygons created during overlay when shared boundaries do not align perfectly

What is Proximity analysis?

• Looking at what’s close to each other

  • Spatial relationships are analyzed by qualifying distances (aka asking “What’s near what?”)

  • Proximity analysis can be applied to resource management, such as by adding wildlife protection buffer zones, setback distances, etc

What are the 3 tools in Proximity analysis?

• Buffer: A distance polygon zone around points, lines, or polygons with a set distance

• Near/Generate near table: Calculates the distance, angle, and location attributes between the input features and the features near it

• Thiessen Polygons: Divides space into proximal zones where any location is closest to its associated sample point

What are the 8 buffer tools used in Proximity analysis?

• Zone of Influence

• Vector Feature Support

• Variable Width

• Multi-ring

• Doughnut Buffer

• Setback Buffer

• Non-dissolved Buffer

• Dissolved Buffer

Zone of Influence

Generates polygons around a feature where the polygon boundaries are all the same distance away from it

Vector Feature Support

A big circle around the entire vector things of interest (?) like a big circle around a bunch of points, or lines, etc

Variable Width

The buffer distance changes depending on its location relative to the feature

Multi-ring

Different buffers are applied to thing (like the rings of a target)

Doughnut Buffer

Excludes the thing that’s in the middle, which we don’t want

Setback buffer

Creates an internal buffer inside a polygon boundary

Non-dissolved buffer

Distinct entities overlap, with overlapping buffers preserved (figure e)

Dissolved buffer

Turned into a single polygon feature, with distinct buffers dissolved (buffer f)

What are the 2 ways to use the Generate Near Table tool for proximity analysis?

• Proximity metrics: Calculates the distance, angle, and coordinates between input features

• Standalone Table Output: Creates a standalone table, that can be used for finding multiple nearest features within a certain radii

Thiessen Polygons (Voronoi Diagrams)

Polygons that are made from point data, where each polygon represents an area around that specific area (Eg: for creating an average rainfall map based off data collected at specific stations)

What are the two applications of Thiessen Polygons?

• Proximal Area Zones

• Environmental Applications, like populating maps

Proximal Area Zones

Dividing the spaces around every location so that the polygon is always closest to its associated point than it is to any other point

ModelBuilder:

UNites the data that’s being modified into how you want it by automating the workflow through pipelines, which can then be shared, edited, and rerun across different spatial datasets

What are the two tools within ModelBuilder?

• Data Elements

• Geoprocessing tools

Data elements

The input variables that represent the input feature classes, tables, or derived output datasets

Geoprocessing tools

The specific tool modification that we want to use on the input variable

State the fundamental components that collectively constitute the field of geomatics

Global Navigation Satellite Systems, Photogrammetry, Geodesy and Land Surveying, Geographic Information Systems (GIS), Cartography, Remote Sensing, Hydrography

What was the earliest use of GIS?

1854: John Snow uses an early form of GIS to trace a cholera outbreak to a contaminated water pump in London

What was the key event in GIS history that took place in the 1950s?

Attempts were made to convert paper maps into computer usable forms (automated cartography) but with limited use (mainly by the government)