GIS Test 2

Primary v Secondary and raster v vector

You use someon elses' data, reused from another cource, data capture - direct entry, data transfer - ppl give you data and then you manipulate it in some way, importing existing digital data Rastrt: Scanned maps, digital election and Vecot: shapefiles, manual.

Raster, primary measurment of physical, chemical, and bilogical properties of objects with out direct contact. satelitte imahery and aerial photography.

registrationeorefrencing
- Control points in image/ on ground or rom gis layer Generating gis layers with RS
- Classification results
- Heads up digitizinf
Benefit of updating GIS layers with RS
- Currency: Provides coverage over large spatial areas quickly
- Editing: use old map and update that with new remotely sense data

Spatial resolution: size of pixels
Radiometric resolution: amt of infor in each pixrl
Spectral resolution: sensitivity to electromagnetic spectrum
Temporal resolution: time between imagery capture

Raster, Secondary
Using a scanning device to convert hard copy analog media into digital images
Images used as a background for digitizing
- Georefrence
-Graphic wallpaper
-Template for vectorization

Reduce wear and tear, improve access, provide database indexing and storage
Provide geographical context and historical record
Scan prior to vectorization (Creates raster data set that can be vectorized - auto and manual)

Vector, primary
Determined by measuring angles and distances from known points with GPS traces and waypoints
Mostly small geog areas of large scales
Geodetic surveys
Plane surveys
Horizontal surveys
Vertical surveys

the art and science of measuring the surface of the earth and its features

Take into account the true shape of the earth (X, Y & Z)

Treat the earth as flat surface (X & Y)
Most common
Used for legal boundaries, construction, etc

position of features on the ground (X & Y)

Determine elevation or heights of features (Z)

vector, primary
A constellation of GPS satellites orbiting the earth is used to determine positions of ground recievers
Traces and waypoints: Constellation of satellites used to determine positions of ground recievers
Collected data
- Immediate positions (field)
- Post processing GPS data (office), Differential correction (potential errors based on atmosphere, movement of satellites, etc,) allows for comparison to other consistent data set
Referred to as GNSS internationally

Trilateration: Need to connect to at least 3 satellites for x,y position
4 satellites is even more accurate, good for vertical measurements

vector, secondary
Puck on tablet
Easiest, cheapest, simplest
Stream digitizing vs. click click

vector, secondary
From a map on your screen
Ie. scanned in map or aerial photograph
Very often the most economical
Used in open street map assignment

important because unprojected/incorrectly projected or variable data sets within same project will frustruate/jeapordize your analysis
Make sure you are using same coordinate system

vector, primary
Process of finding associated geographic coordinates (often expresses as lat or longi) from other geog data like street addresses or postal codes

raster, secondary
When you georeference your raster dataset, you define its location using map coordinates and assign the coordinate system of the data being used
General steps
- Add raster database you want to align w projected arcgis pro data
- Add control points that link known raster dataset positions to known positions in map coordinates
- Save the info
- Can permanently transform the data if you want

assigns output values that depend on the specific set of input values
Based on matching input cell values to a reclassification table
Usually a single output value applies to a range of input values

usedd with raster data, converts it to vector
Batch vectorization = automated process

Radar imaging from space
Differs from optical imagery in that it sends a signal to the ground (RADAR)
Records the part of signal returned to the sensor
Two or more SAR images used for interferometry, a technique used to detect land deformations such as those caused by earthquakes and volcanoes (& other events)

Laser imaging from aircraft (usually)
Like SAR, it sends a signal (laser) and records the return signal, or bounce
Usually mounted on aircraft, rather than satellite
Used to detect shape & surface characteristics including deformations & changes in land cover, e.g. post-hurricane beach changes

High resolution
Centimeter accuracies
Bare-earth detection in forested terrain

"fitness for use" of data for an intended purposeelative accuracy and precision of a particular set of data
Understanding data quality is important because without it we do not know what confidence to put in the results of our analysis
Results are only as good as the input
Data are considered of sufficient quality if they meet fitness-for-use criteria

data may be used in ways not foreseen by their producers and by users without the knowledge or experience to judge whether an application is appropriate
GIS programs have ability to hide underlying data quality issues

Authority: credibility of the mapper/cartographer and quality of sources
Accuracy: degree to which information on a map or in a digital database matches true or accepted value
Precision: level of measurement and exactness of description in a GIS database
Currency: age of the dataset
Bias: consistent error throughout a dataset
BUT high lvl of precision is not high level of accuracy!!!

Data collection phase
Data input and editing phase
Methodological phase

Interactive vectorization - snap to features
Post-vectorization editing is required to clean up errors
- Importance of clean input data
- Build topology process: editing and cleaning
- Fix dangling vertices, snapping to nodes, overshootsndershoots, etc
- Set tolerances

The mathematics/science of geometrical relationships used to validate the geometry of vector entities
Topological rules for vector spatial features can enforce data consistency

properties of geographic objects that do not change when the forms are bent, stretched, or undergo similar transformations

Connectivity (Lines)
Directionality (Lines)
Adjacency (Polygon)
Exhaustive (Polygon)
Planar Topology (No overlaps)
Non-Planar (Overlaps allowed)
Dangles

Overlap
Connectivity

Spatial errors
Attribute errors
Conceptual Error
Procedural/Analytic errors (Logical Error)

statistical change that occurs when changing the size of spatial unit of analysis
Problem associated with aggregate data sources
Use of Arbitrary spatial units
Problem of Scale

errors due to performing analyses on aggregate data when trying to reach conclusions on the individual units
Like MAUP, it is a statistical misconception

Turning raw geographic data into useful information
- includes all manipulations/methods applied to Geographic data, to add value, support decisions, and reveal patterns and anomalies not immediately obvious
- Effective Spatial Analysis requires intelligent user, not just powerful computer
- Spatial Analysis helps in situations where eyes might otherwise deceive us

Location
Quantity
Patterns
Trends (Temporal Aspect)
Conditions & Relationships
Implications (Planning for the future)

measurments
scope
queries
proximity functions
geoprocessing

spatial estimation
area analysis
density

Simple numerical values that describe aspects of, or simple properties of geographic data
Ex. length, area, shape, OR, relationships between pairs of objects, like distance or direction
Distance: Different calculation methods based on data format
Vector Distance (Euclidean Distance)
Raster Distance
- Euclidean Distance
- Manhattan Distance
- Proximity

Geographical extent or area of the input data used to determine the values at output locations
Characterization of Scope: Local, Neighborhood, Global

Primary method of data retrieval
Allow us to create new information, but doesn't change older/existing information
Types of Queries:
Aspatial (non-spatial)
- Set algebra (<, >, =, etc)
- Boolean queries (or , and , not)
Spatial
- Adjacency
- Containment

buffers
spatial join
thiessen polygons

Creation of zone(s) of interest (inclusion or exclusion) around an entity

Fields from one layer's attribute table are appended to another layer's attribute table based on relative locations of the features in the two layers

- This method assumes the values of un-sampled area are equal to the value of the closest sampled point
- Mathematically defined by the perpendicular bisectors of the lines between all points
- Created from point data

Involves using data from one or more spatial layers and integrating it/them to form a new, single layer
- clipping
- dissolve
- intersect
- union
- identity
- erase/difference
- merge

Creates a new layer by using a polygon layer (or selected polygons from a particular layer) as a cookie cutter on a point, line, or polygon shapefile
The output layer contains information from Layer A only. Layer B is only used to define the new boundary

Dissolving features in a layer coalesces features that have the same attribute value
extremely important if you are trying to create a new shapefile, a file with a coarser layer of geography than your starting files

The intersect method preserves only those features falling within the spatial extent common to both layers
- features of the input layer are intersected or sliced by intersect layer
- attribute data from both layers included in the new layer's attribute table

- creates a new layer by combining two polygon layers
- new layer has data and shapes from both layers, including their intersection

- Computes a geometric intersection of the input features and identity features
- input features or portions thereof that overlap identity features will get the attributes of those identity features.

Geometries that are coincident between the Input Features and Erase Feature parameter values will be removed

Using merge is similar to union; a new layer is created from multiple layers but their features are not intersected
- allows you to combine the features from two or more layers of the same geometric type

Overlays are the combination of spatial and attribute data from two or more spatial layers
Polygon overlay: The output polygons has attribute properties from both parent layers

intersect method preserves only those features falling within the spatial extent common to both layers.
The features of the input layer are intersected or sliced by the intersect layer
Attribute data from both layers included in the new layer's attribute table

Union creates a new layer by combining two polygon layers. The new layer has data and shapes from both layers, including their intersection.
In fact, union differs from intersect only by the fact that all the features of both layers are included in the resultant layer, including those features that did not overlap.

form of spatial overlay analysis
Polygon to point: Adding to the attribute properties of a point feature based on the polygon in which it resides
Point to Polygon: summarizing the attributes of all points within a given polygon
Spatial join = basis of point in polygon

spatial interpolation
TIN (triangulated irregular network)
thiessen polygons

procedure of estimating the values of properties at un-sampled sites within an area covered by existing observations
Widely used for:
- Climate Data
- Predictive stats
Data must be spatially auto-correlated
Only works for continuous variables

This method is used to construct Digital Elevation Models (DEM)
Adjacent data points are connected by lines to form a network of irregular triangles

This method assumes the values of un-sampled area are equal to the value of the closest sampled point
Mathematically defined by the perpendicular bisectors of the lines between all points
Created from point data

by area and by shape
area
- Calculation in GIS
- Difficult to measure by hand but simple in a computer
Shape
- Basically, calculating the perimeter relative to the Area
- Application of this factor means something resembling a circle would return the value of 1, and very distended or distorted shapes will have much higher value

Point
Line
Kernel

Calculates a magnitude per unit area from polyline features that fall within a radius around each cell

Calculates the density of features in a neighborhood around those features
Magnitude of process per unit area (total kernel density/areal unit)
Kernel height
- Default of 1
- Can assign height based on attribute using population_field parameter
Search radius
- At what distance does this process effect the system of interest
Density estimation using two different distance parameters in the respective kernel functions

Biases are present
Ppl take maps at face alue
Influence decisions and behavior
All maps represent world from some perspective
Understanding perspective important to help avoid inherent bias
How you represent your data matters
- Projection, symbology, class breaks, etc

Stringing together series of functions in order to create new spatial layers
Model builder: geoprocessing models in ESRI
- Feeds output of one tool into another tool as input
Basically to demonstrate process and what you did

- mode of production for software and data
- Permits users to use, change, improve the software, and to redistribute it in modified or unmodified form
- Often developed in a public, collaborative manner
- distinguished from closed source, or proprietary software & data

Human-readable source code is made available under a copyright license that meets the Open Source Definition
Data distributed under a 'share alike' scheme. I.e., you can use it, modify it, but must share it under the same terms

Free Redistribution: the software can be freely given away or sold. (This was intended to expand sharing and use of the software on a legal basis.)
Source Code: the source code must either be included or freely obtainable (Without source code, making changes or modifications can be impossible.)
Derived Works: redistribution of modifications must be allowed. (To allow legal sharing and to permit new features or repairs.)
Integrity of The Author's Source Code: licenses may require that modifications are redistributed only as patches.
No Discrimination Against Persons or Groups: no one can be locked out
No Discrimination Against Fields of Endeavor: commercial users cannot be excluded.
Distribution of License: The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.
License Must Not Be Specific to a Product: the program cannot be licensed only as part of a larger software distribution.
License Must Not Restrict Other Software: the license must not place restrictions on other software that is distributed along with the licensed software.
License Must Be Technology-Neutral: No provision of the license may be predicated on any individual technology or style of interface

built on the same principles of openness, transparency, and consensus as open source software.
Open standards lay the grounds for innovation, growth and fair competition by establishing functional criteria
Open standards are not synonymous with open source. Open standards are specifications that outline required functionality
Open Source software & data are implementations that follow specifications
Open standards dictate what software/data should be, not how it is developed

By collaborating, we can lower costs, open to new sources of contributing talent
Encourages innovation/Speed of innovation
Lower total cost of ownership (TCO)
Faster bug fixing & community response
Establish de facto standards with re-usable code & data

OSI was formed in 1998 as an educational, advocacy, and stewardship organization
Enables a development method for software that harnesses the power of distributed peer review and transparency of proces
Standards body, maintaining Open Source Definition for good of the community

Not-for-profit organization
Mission is to support and promote the collaborative development of open geospatial technologies and data
An incubator for open source geospatial software

Open Source lowers barriers to entry
Allows participation, interaction and immersion
- Crowdsourcing
- volunteered geographic information

Accessible: Open geospatial data and low-cost, open source geospatial tools are making everyone a geographer and expert on locational awareness
Utility: Applications in tourism, insurance, community development, urbanegional planning, economic development, disaster preparedness & response, and more
Value: Open source GIS has the same capabilities as proprietary software at a much lower price, making it an exceptional value

Open source tools tend to be loosely coupled
Open source tools depend on an open internet
As infrastructure to distribute data/software
As an institutionally neutral platform for collaboration

Crowdsourced map of the world w an open content lisence so anyone can edit map and use the data
Like wikipedia for maps
Collaborative map of the entire world
Data project, not software

open source, desktop version
Can basically do all the same stuff as ARCgis
Is free
Plugins
Free to download/install
Developed by independent orgs and developers
Hundreds available

ushahidi, Open Data Kit, GeoNode, StreetComplete

GPS - ground surveying w GPS unit
Local knowledge
Imagery/trace features
Sources - purchased/donated imagery, bing

Java open street Map Editor
- Desktop editing application for OSM
- Advanced editing tools in a stable environment
- "Check out" data to edit offline
- "Push" data back up to the server, with validation checks​​
Field papers
- print atlas, take paper into field
Mobile mapping
- apps support mapping in field on phone (Vespucci, OSM GO, StreetComplete)

Assist educators to introduce open source mapping and OSM in the classroom

international team dedicated to humanitarian action and community development through open mapping.
Developed Tasking Manager for collaborative mapping

Data produced can be used to invade privacy
Data are used to inform policy decisions
GIS technology has potential to exacerbate societal inequities

Applies to collection, analysis, and visualization of data
Collection and analysis
- Research or crowdsourced?
- Cleaning of data of Personally Identifiable Information (PII) before shared
- What of security sensitive data?
- No official standard for geospatial industry
Ethics need to evolve w industry

professional/industry organizations
UNICEF: Focuses on how geo tech are used to protect vulnerable populations
American Geographical Society (AGS): EthicalGEO, prioritizes privacy, politics, ppl, planet, property
Code of ethics

Maps should be evident, not deceptive or confusing
Know your audience - facilitates effective communication
Do not lie w your data
Show all relevant data as completely as possible
Dont discard contradictory data, remain neutral in data portrayal
Portray your data accurately
No plagiarism
Choose neutral symbols to minimize bias
Repeatability of work
Sensitivity to cultural valueseliefs

maps affect perception
Maps can inform but deceive
Deceptive maps have existed for ages and hide critical info
Maps need to show appropriate info for the reader to make an informed decision
Inappropriate mapsraphics lead to misunderstanding
When you map a phenomenon consider
- Data standardization (population in geographic area)
- Color choice

A map typically created using GIS or similar technologies
- OpenStreetMap as source
- ArcGIS or QGIS as editor and analysis
Served on the web, consumed on the web
A service (continuously available online), rather than a product (physical paper)

May have flexible modes of consumption
- Filters to choose what features to display
- Tools to change display colors, icons, emojis
- Option to print or export .pdf
May serve static maps or real-time maps
May permit editing by users

All interactive maps have some sort of contextual data
Base-maps are the most commonly used type of contextual data
Services such as Google maps, Bing, Mapquest, Mapbox... provide base maps
Due to relatively static nature of data, typically served up in image (raster) tile format

Vector map tiles
- More recent technology to share maps
- Geography divided up much like raster tiles, but using compact pre- generated vector data
- Rendered on the client side with opportunity to customize the map style

Tiled maps cache efficiently: If you download tiles of Manhattan to view a map of Central Park your browser can make use of those same tiles from cache instead of downloading them again when showing a map of Jersey City.
Tiled maps load progressively: Central Park will load before the outer edges of Manhattan letting you pan or zoom into a particular spot even if tiles at the edges of your map view haven't finished loading.
Tiled maps are simple to use: The coordinate scheme describing map tiles is simple, making it easy to implement integrating technologies on the server, web, desktop, and mobile devices.