-physics

-sensors (photographic and digital)

-photogrammetry (taking measurements from photographs)

-how GI (geographical information) is made

Remote Sensing future.... includes possibility of advanced sensors and digital analysis

-making maps

-variety of sources from clay tablets, writing on sand, to paper maps

-key to survival of people

-key to economic growht of kingdons, nations, etc

-maps were money. nothing has changed

WAR YEARS- Mapping Gets Serious

-advent of flight and photography ~1909 (photography ~1839)

-combine technologies during the First World War.. perfect them during second

-it takes less than 50 yrs from the start of aerial photgraphy from a place to get to digital imaging

Aerial Photography/Imaging

Measurement (physical/chemical)

Data

Date with structure- digital maps and analysis

Advanced computer mapping and modelling

Databases

Geospatial Revolutions

-last 5 yrs or so. It is everywhere now.. google microsoft

-advanced photography

-digital imaging

-satellites (all types)

-high altitude and high speed flight

-rockets

-digital image processing (photoshop)

We live in two worlds: the natural environment and the build environment. These are increasingly in conflict. We have to re-learn how to "fit in".

The natural environment is self-regulating, the build is managed.

Trying to:

1)See the Whole (large scale- patterns, linkages, trends)

2)Manage Places (small scale- watersheds, communities, neighborhoods, districts)

We must abstract the real world to model it and perceive it.

GIS= Geographical Information System

-links databases and maps

-manages information about places

-hard part is trying to link "managing places" to "big picture"

-most geography is not done at a global scale

-The discrete pieces don't understand the connections. That is our job

Helps answer questions such as:

-where is it?

-what else is nearby?

-where is the highest concentration of X?

-where can I find things with characteristic Y?

-Where is the closest Z to my location?

GEOGRAPHIC- 80% of gov data collected is associatd with some location in space.

INFORMATION- attribues, or the characteristics (data), can be used to symbolize and provide further insight into a given location

SYSTEM- a seamless operation linking the information to the geography - which requires hardware, networs, software, data, and operational procedures

GIS data has a spatial/geographic reference

This might be a reference that describes a feature on the earth using:

-a lat/long

-a national coordinate system

-an address

-a district

-a wetland identifier

-a road name

A GIS stores information about the world as a collection of thematic layers that can be linked together by geography.

GIS provides Data Integration

-roads/land parcels/population/utilities/land mines/hospitals/refugee camps/wells/sanitation

Integrates:

-topology

-vectors (lines)

-images (squares)

-networks

-3D objects

-addresses

-terain

-CAD drawings

-attributs

-annotation

-surveys

-dimensions

Vector

-a seris of x,y coordinates

-for discrete data represented as points, lines, polygons

Raster

-grid and cells

-for continuous data such as elevation, slope, surfaces

Vectors are mostly two-dimensional (continuous vs discrete data)

MT Q: Compare and Contract Vectors and Rasters

-Produce good cartographic products

-Generate and maintain metadata

-Use and share geoprocessing models

-Managing data in a geodatabase using data models for each sector

GIS in:

EDUCATION

-over 7000 universities worldwide teach GIS

-used in MANY disciplines

AGRICULTURE
-farm management

-pest/disease tracking

-crop monitoring

-yield prediction

-soil analysis

-precision farming

NATURAL RESOURCE MANAGEMENT
-forestry

-ecology

-mining

-petroleum

-water

-wildlife

PLANNING/ECONOMIC DEVELOPMENT
-land use/zoning

-emergency preparedness

-populaiton forecast

-market analysis

-property tax assessment

-transportation

-cell phone (addressing)

-multidisciplinary

-a real-world technology using real data

-involves authentic tasks/assessments

-promotes holistic/systematic approach

-engages multiple ways of learning

-encourages community connections used at scales from local to global

Today's challenges require a geographic approach:

-climate change

-urban growth

-sustainable agriculture

-water

-international security

-energy

-epidemiology/Disease tracking

-natural hazards

GIS skills needed in workforce!

-in 204, US Secretary of Labor identifid geospatial technology as one of the 3 most important evolving fields

-GIS part of Canada's Job Training Initiative

-Major NSERC education programs for secondary, technical, and adult education programs

(Real World GIS)

Because GIS is used in many departments, coordination is needed

-software licensing

-instruction

-data

GIS is Rapidly Evolving!

-From Integrated Projects

-To Coordingated Systems

-To Cooperative Networks

-To Collaborative Societal

Data is the greatest expense

-previously, data scattered in multiple departments, not coordinated

-in the future, data will be accssible anywhere, GIS portal and Web services will facilitate sharing

Definition - the technology, policies, standards, human resources, and related activities necessary to acquire, process, distribute, use, maintain, and preserve spatial data.

-Part of many nation's e-Gov strategy (www. GSDI.org)

1% of the landmass can be currently acquired every day at 0.5m resolution BUT..

*current system designs do not allow to receive the data that can theoretically be collected daily.

-Even at that rate and with perfect weather, it takes about 6 months to cover the entire landmass.

DATA OVERLOAD!

-Imaging platforms have become numerous (one 1m sensor in 1999, 10 or so in a few years)

-Sensor data volume per platform has increased enormously due to scene size, improved resolution, and number of data channels)

-Too much data collected er day to be analyzed by humons.

1998- first consumer mapping website

2001-Keyhole founded

2003-Keyhole product released

2004-Google Acquires it

2005- Google maps, google earth, microsoft virtual earth

2007- GPS

Over the years...

-resolution and cost/performance index have decreased

-data price per km2 has increased

-system cost of earth observation satellites has increased

**Satellite imagery costs are growing 2 times faster than the systems capitalization cost would explain

STILL NOT THAT AVAILABLE! THE FUTURE USER IS NOTE A GIS EXPERT!

-public use and availability is the key!

Where are we going?

-convergence of remote sensing, geospatial and web technologies is creating significant new utilizations and demand for geospatial imagery

-great proliferation and improved quality of global imagery fuels new applications and increase demand

-satellite imagery is finding its way into mass market applications.

-Complex GIS functionalities are hidden behind friendly user interface

INDUSTRY TRENDS
-Forward-thinking actors Google, Microsoft, and others are going to cintinue to drive new imagery use (a shock for the GIS world)

-Under international competition pressures, the satellite industry's internal self-protective politics becoming largely irrelevant, the way telephone companies monopolistic approach did in the 1980's

**We witness teh beginning of hte proliferation of sources of high resolution of satellite imagery

GOING FORWARD

-Imagery portals have created a new set of non expert users who are developing application of imagery beyond traditional GIS applications

-Three key factors are driving this outcome:

*1)Ease of access and use (growth of the internet as a global platform for applications)

*2)Significant usability improvements and convergence of technologies (elimination of the GIS technical expert)

*3)Spin-off from the "Professional" to the "Casual User" (Virtual globe applications have produced greater awareness of the potential uses of satellite imagery)

PROCESSING TRENDS

-We will be rapidly choking on data volumes

-A lot of software development needed for automation

A "1day-1earth-1m" system is on the drawingboard: this is 125 TB of data per day!

WHAT IS NEEDED?

-Higher Resolution

-Shorter Revisitation

-Reasonable User Fee

-Remove the "man-in-the-loop" as much as is possible for data processing

-easy distribution/access

-open standard and interoperability between the various converging technologies

Innovation is driven by mainstream users, not GIS experts

-It would be nice if companies stopped inventing new image formats for each new satellite or imagery solution

-Vendors will have to start paying more than lip service to open standards (ie. be able to open the files consistently.. one software than can do anything)

**We (users) must encourage open standards, open format initiatives, and open source software/algorithms

Must improve interoperability between systems (opposite of interoperable is "software specific"

-Data Acquisiiton

-Data Processing

-Data Storage

-Use Enabler

-Web Serving

-Web Delivery

*Want integration and automation of all phases*

Digital acquisition can solve many of the acquisition problems, but there are still major bottlenecks

-one color scene (15km2) at 0.5m is about 1.5GB

-total imagery collection capacity per day for GeoEye and DigitalGlobe is about 6TB/day

Today lossless compression ration is abotu 4. At current downlink speed the typical satelite duty cycle does not allow to retrieve that data daily. Lossless compression ratio of 10 is required to download what is collected.

This is the big challenge

Based upon the previous collection capacity of only two systems, we globally need to process maybe 2TB/hr (for value added products/mosaics and orthophotos). We are far from that.

Earth landmass is about 900TB at 0.5m resolution

Future trends will be towards automated grid computing solutions for geolocation, mosaicking, color balancing, and compression.

2TB drives today; 20TB drives soon

Satellite operators need to take a hard loo at their storage and retrieval approach: e-business

Future approach to backup imagery is:

-cheap delivery solutions: high bandwidth streaming

-off-site hard disk replication (mirror sites)

USE ENABLER

-current licensing business model is huge roadblock for the development of a mass user base and to leverage the full potential of omnipresent satellite imagery

-Governments are the main (only?) funding entity behind this industry and need to consider Satellite Imagery as part of the country infrastructure (like GPS, roads, airports, etc.)

Short of a free access we need to devise a user's fee based method of cost recovery just like forroads and airports

EASY OF USE
Acess enablement tecnologies pretty much exist (Google Earth, Virtual Earth, etc)

What needs improvement is global bandwidth access

The typical user (a non specialist) needs simple intuitive tools.

Web Delivery

-peer to peer delivery proven to share TB's of imagery to lots of users

-35% of all internet traffic today is P2P

-kep it simple!

WEB SERVING

Pretty muc hsolved today (google, etc)

Big challenges:

-increasing integration

-adding value

-availability of imagery

-New instruments, new ways to collect data

-massive archival systems

-new ways to analyze data and to make sense of it

-automated processing

-the major limitation is the inability to quickly extract the information we need from the data we have...

-Human interactno (at a higher level) may still be embeddd in the system for the foreseeable future

Need to owe the cost of products by implementing a new Service Oriented Architecture (SOA)

-sharing open source science algorithms

-creating standard interfaces for tasking sensors via a SOA standard

-making sensor capabilities and models, data sources and algorithms non proprietary

-allowing users to create new algorithms out of existing algorithm components

Web based services required by the non-speciality user

-Sensor Planning Service (SPS): details or capability and availability of sensor (whether in-situ or on-orbit) and provides automatic means for user to task sensor. Develop a universal language used to self-describe sensor capabilities and availability.

-Sensor Observation Service (SOS): provides observation data to user.

-Web Processing Service (WPS): classifies desired features

-Web Mapping Service (WMS): produces maps

-Web Coverage Service (WCS): places features on map

___________

THING/CURRENT/VISION..

-Processing algorithms/custom/open source building blocks

-Interoperability/ow priority/high priority

-Time to create&implement new algorithms/months/minutes

-Cost to ""/high/low

-Sensor access and tasking/cumbersome/automated

value added processing automation/average/high

-Data storage and transfer requirements/high/low (filter and transfer only nedd features;archive virtual products)

-Ease of finding and reusing existing algorithms/difficult/easy

Most of the basic technology needed is here today and few technical hurdles remain

Big challenges are in other areas:

-Data licensing policy

-Pricing policy

-Standardization of formats

-Open standard acceptance

-interoperability

Movie... http://geospatialrevolution.psu.edu/episode1/complete... TESTABLE!

Think about the applications

Solutions from outside of GIS

NOTES
-look where people work

-most info now has geospatial tag

-GPS receiver collects signals from space.

-US Marine corps used geospatial info to find how they could get into Haiti

-can create and map the situation on the ground

-maps b4 earthquake were't up to date.. data was donated, could find hospitals, etc.

-2000 volunteers from 49 countries contributed to the mapping of Haiti

-info forwarded to aid organizations

Remote Sensing: The technique of obtaining information about objects through the analysis of data collected by special instruments that are not in physical contact with the objects of investigation

Remove Sensor: The instrumentation that is responsible for the collection of information from a distance.

Data Collection

-Wide variety of sensors

-Electromagnetic Energy (photographic, digital[sat], RADAR)

-Acoustical energy (SONAR)

Data Analysis

-Manual extraction of information

-Automated extraction of information

-PRimary source of information for Earth resources management

Cambrian: First fossils with eyes

1839: Public disclosure of first photographic proceses

1858: First known aerial photograph using a balloon (80m)

1882: kites used (up to 600m)

1903: invention of airplane

1909: first aerial photos from plane

WWI: first maps from oblique photos

WWII: aerial photography flourishes

1970: sat imagery becomes available

pres: photography still one of most important remote sensing tools

1. Improved vantage point

2. Stop action (image of whatever is going on)

3. Permanent record

4. Broad spectral range.

5. Spatial resolution/photogrammetry

View large areas from remote location.

Patterns not evident on the ground (too close)

Observe in different ways (areas of EM spectrum)

Temporal scales (historical record)

Reduce ground visits

Availability

Overall cost

DATA ACQUISITION

1.Enegy sources (ie. sun)

2.Propagation ofenergy through the atmosphere

3.Energy interactions /w surface features (absorption, reflectance, transmittance)

4.Retransmission of energy back through the atmosphere

5.Airborne/spaceorne sensors

6.Produce analogue photograph or digital image

DATA ANALYSIS

1. Examine data (qualitative)

2. Data correction (geometric, radiometric)

3.Interpretation and statistica analysis

4.Classification scheme design

5.Accuracy assessment

6. Hardcopy production and/or integration with GIS

7. Results used in decision-making process

Dynamic form of energy caused by the oscillation or acceleration of an electrical charge

-assocation with atomic nuclei during  fission and fusion reactions

-All matter above absolute zero (-273C) emits electromagnetic radiation.

ENERGY SOURCES
-Wide range of sources of natural and artificial EMR
-The Sun emits greatest amount of radiation in the visible part of the spectrum

-Wide range of different possible energy regions.

Wavelength: the distance b/w successive wave peaks

-usually measured in micrometers or nanometers

Cycle: one coplete wave; one wavelength

Frequency (v): the number of cycles per second passing a fixed point.

Different spectral composition nd magnitude from visible light.

-Gamma rays, X-rays, UV, infrared, mocrowaves, radiowaves

-Differ in wavelength, frequency, and energyd

Energy defined: The capacity to do work, and can be mechanical, chemical, elextrical, and electromagnetic.

3 methods of transfer of energy:

-conduction (direct transfer by physical contact)

-convection (energy transfer through a medium (liquid or gas) in direct contact)

-radiation (energy transfer without an intervening material medium)

EMR: Electromagnetic energy in transit

-only detectable if it ineracts with an object.

-travels the speed of light (299,292.8 km/sec in vacuum)

-described by two related models, wave and particle

WAVE MODEL OF EMR

Wave model looks at EMR as a series of continuous waves that are equally and repetitively spaced.

One wave is electric and the other is magnetic (occur perpendcular to each other).

EM waves travel at the spped of light (3x10^8m/s)

c=(frequency)(wavelength)

QUANTUM MODEL

Electromagnetic energy is composed of packets of energy or "quanta".

Energy of quantum is:

Q=hv

h=Planck's constant (6.626x10^-34Jsec)

v=frequency

Combined Models

v=c/wavelength

Q=hc/vavelength

*Longer wavelengths= lower energy content.

Incoming = irradiance

-top of atmosphere

-diffuse sky

-global incident on target

Outgoing = radiance

-at sensor

-total from target at sensor

-intrinsic (at target no atmo...?

The target that the sensor sees depends on the angle of reflectance, which depends on both atmospheric thickness and and wavelength.

Basic pinhole Camera (upside-down image)

Basic Single Lens Camera (SLR)

-film at focal plane

-adjustable diaphragm

-focal length - distance from focal plane to lens

-shutter is behind adjustable diaphragm

-SLR= single lens reflex

-lens helps to focus

-film records

-adjustable diaphragm controls light getting in

MAPPING CAMERA
-fanciest camera (~$250000)

-500ft spools of film

-piece of film is size of sheet of paper

-sucked up by vacuum (otherwise floppy)

-need two people to move it

-data block auto-records information

-shutter in lens

-optics are fast (emit lots of light)

-lenses are expensive part

-Large number of variables make up image quality:

1)Quality instrument

-flat film plane

-quality optics

2)High definition film

3)High contrast target

*for good quality, rely on both the camera and physics.

Instrument (camera) improvements

-ie. why mapping camerais better

Large format helps

-contact size is 23cm by 23cm

-lots of film compared to a 35mm camera which is only 24/36mm

Problems with technique

-platform moves while image is taken (forward motion compensation)

-Difficult to isolate just the optical properties

-Easier to do if running comparisons b/w lenses

-Static target... what can it resolve?

-Sort of like going to the optometrist

-use a resolution test pattern

Focus

-achieved by moving lens

-focal length fixed for each lens

-always infinity in aerial photgraphy

Exposure

-amount of light reaching the film

-shutter speed (duration of exposure)

-relative aperature (amount of light per unit time)

-geometric differences

-map gives directly above view

-photo has a central focus point, and anything not in it is seen from an angle

dead centre of photo= principle point

Vertical (film plane flat)

Low oblique (film plan slightly tilted, optical axis is a small angle from perpendicular to the ground

High oblique (film plane very tilted, optical axis is a large angle from perpendicular to the ground)

Need to view two images separeately for stereoscopic vision (convergence angles)

Stereoscopes separate each eye so they only see one image at a time

many different types of stereoscopes

Some people can veiw stereoscopic imges without the aid of a stereoscope (magic-eye procedure)

eye base = distance b/w eyes

instrument base= distance between prinicipal point on both photographs that you are viewing.

photo base = distance b/w principal point and Conjugate Principal Point (CPP)

Pseudoscopic Vision

-reversals of highs and lows, hills are valleys, rivers running on ridges, etc.

-caused by viewing the left image with the right eye and vice versa

-image parallax is reversed (left shifted image is viewed by the left eye and the right shifted image is viewed by the right eye)

-can also be caused by viewing topography illuminated from the bottom of the image.

Photographs are projections of a 3D world onto a 2D plane

Our eye works the same way as a photo, each eye observes a 2D image (monocular vision)

Our brain converts the images into 3D (binocular vision)

-Results in depth perception

Binocular Vision

-each eye focuses on an object viewed from a slightly different position (retinal disparity)

-brain reconstructs the 3D image by fusing the two images from the eye

Monocular Clues:

-focusing accommodation

-perspective

-movement parallax

-relative object size

-overlap

-highlights and shadows

-atmospheric obscuring of fine details as result of distance

Scale = f/H

f=calibrated focal length of lens

H=flying hight (AGL)

either 1)based on relief displacement. (need to know AGL, displacement of bottom and top of object on map, and radius)

or 2) based on shadow length on level terrain (need to know angle of sun's fays and length of shadow)

Def: The process of identifying objects or conditions from aerial photography and determining their meaning or significance.

Not simply identifying features.

*Part ART, part SCIENCE

Interpretive Process

-interp is a subjective judgement

-based on deductive reasoning and logic

-requires prior knowledge of the area/feature

-requires interpretor to have a very broad range of knowledge and experience.

Wide # of characteristics of areas that are used in deducing what the feature is

Shape- external form or configuration of an object

-built forms are normally regular and geometric

-natural forms are irregular

Size- in 2D space size is a measure of the surface dimensions

-relating size comparisons are important (house vs apartment)

-comarative size (tributary vs main stream)

Pattern- Overall spatial form of related features, esp repeated forms

-cultural (settlement patterns)

-agricultural (trees in an orchard vs forest)

-mainly built forms

Shadow- Cast by oblique illumination of an object

-gives clue to the 3D form (ie trees)

Tone/Colour - Reflective characteristics of the object within the photographic spectrum

-the ability of an object to reflect light is dependant on its surface composition, physical state, and illumination angle and intensity

Texture - The visual impression or coarseness or smoothness caused by the variability of image tone.

-texture is a visual perception (happens instantly)

-features can have the same general tone or colour and can only be distinguished by texture (certain forest stands for example)

-texture also changes in response to different illumination angles

Association - Certain features are always found together

-large buildings and large parking lots = mall

-veg along river courses

Site - the location of an object in relation to its environment

-Nuclear power andwater

-black spruce and swamps/pine on dry sites.

-Set of established guidelines for identifying features

Two types: selective and elimination

Selective keys are made up of examples that are used for comparison

Elimination keys require the user to follow a sequence of steps (if A then go to 1, if B go to 2, etc)-

-elimination keys usually for more complex or foreign environments

SUCCESSFUL INTERPRETATION

-Gather information sources (photos/maps)

-Familiarize yourself with study area and with interpretation key

-Field work: validate interpretation key

-Identify objects, map boundaries

-Classify objects or areas

-Field work: validate classifications

-Re-classify objects or areas if necessary

-Interperet results (map)

-Write report

350-750

purple-blue-green-yellow-orange-red

We can quantify certain features about an object from a remote sensing image.

Starting points:

-complexity of the feature: colour, tone, size, shape, shadow, texture, pattern, site, association (less complex = easier interp.)

spectral data - data that relates to the intensity of light as a function of wavelength

spectral signature - specific combination of reflectance and absorption properties which vary by wavelength and are unique to a target

spectral band - A region of the electromagnetic spectrum that is viewed as a discrete extraction from the continuous spectrum

Multispectral imaging - an imaging system that is composed of several spectral bands

hyperspectral - many relatively narrow spectral bands

hyperspectral imaging - an imaging system that has many more bands

-Establish the purpose of the map

-Define the final scale of the map (printed or viewed on screen)

-Select the features that must be portrayed

-Choose a method of representation of these features

-generalize the features, for clarity

-adopt a map projection

-apply a spatial reference to the design (graticule, neat line, etc)

-annotate the map with a key/legend, text, scale bar (multiple),  orientation

All maps are generated for some reason

-tightly controls the sort of representation - general purpose (reference maps) vs thematic maps (special purpose - single use)

-often controls colour selection, layout, symbology

Scale gives an indication of how much smaller than reality the map is

"ratio of distances"

-scale controls level of generalization

-ratio, graphical, verbal

-standard topographic maps have all three

-can be interactively changed in GIS

Maps use a symbolic communication system

-basics include points, lines, polygons

-include 3D and implied

-3D objects are often used as display enhancers (detractors)

-implied-city boundaries-combination of points, lines, and polygons

Lots of options - depends on purpose

-use graduated symbols instead of many individuals

-rivers as real or symbols

-forests as green shade or stand boundaries

Best to try a variety of different methods - have a default set in mind.

Scale selection often controls generalization

-1:5000 is about the smallest map (largest scale)

-graphical scale = scale bar (reproduces /w photocopy)

Methods of Generalization include:

-real to symbol

-reduction of spatial complexity

-elimination of detail

-alteration of symbology

Displacement - features can be moved slightly to increase clarity

Smoothing/Enhancement

-make straight lines smooth

-remove detracting elements and enhance focus

-change symbols

Select a projection that is appropriate for the FINAL presentation of the map

-may have alternate intermediate projections as a convenience

-record the projection information on the map, not just the metafile.

@ small scales (ie. 1:50 000) projection doesn't matter

3 different kinds of north exist

UTM (universal transverse mercator)

-severe distortion of size the further North you go

-one point of contact N-S

-EVERYTHING else is distorted

-higher lat values = higher distortion

-size of Greenland used to tell if UTM

-used for navigation (military)

-shortest distance is a straight line

DO NOT USE UTM TO CALCULATE AREA

All finished maps need SRS (beyond scale bar)

-insertion of graticule

-reference coordinates

-neatlines (enhanced border)

-allows for better map usage

Annotation

-Map keys and legends (placed so they are useful, small, unobstructive) (include all thematic elements) (have consistent style)

-Titles, scale bars (at least 2), and orientation

Put your legend in "negative space"

Scale bars should be graphical, then either verbal or ratio

With graticules, use of N arrow is silly

Objects are entities such as buildings, roads, pipes, properties; they have distinct boundaries; they are considered discrete entities.

Fields are continuous phenomena such as elevation, temperature, and soil chemistry; they exist everywhere (every point has an elevation or temperature); they are not discrete entities.

Spatial DB- Internal GIS Database

Attribute DB- External DB

Arc - Non-straight line between two nodes?

Polygons - use arc and arc direction to combine polygons

Topology refers to the relationships or connectivity b/w spatial objects.

GIS analysis answers many questions:

-Where is it?

-What is it next to?

-Is it inside or outside?

-How far is it from something else?

The mathematical terms for these answers are:

-Where is it? location

-What is it next to? adjacency

-Is it inside or outside? containment

-How far is it from something else? connectivity

Every line starts and ends with a point (node)

Points b/w the start and end are called vertices to define the shape of the line/border.

Lines don't really exist - they represent a relationships b/w two nodes and zero or more vertices.

When two lines cross, and form an intersection, they also have a node, since the intersection is the start of one line and the end of the other line.

Topology describes the connectivity of the lines and nodes.

Spaghetti Digitizing - Old way (non-topologically coded data). You just start digitizing, doesn't matter where. Relationship not defined.

-We don't do this anymore

Discrete digitizing - things make some sense

-ie. do all main streets first

-intersection arises when you do highways on a different map

Lines need direction to define adjacency!

All lines have direction.

***We can create a table that clearly describes location, adjacency, connectivity and containment, or more specifically, a topology table.

(lecture 12, p5)

TEST Q: Create polygon attribute table for adjacency

-define difference b/w spatial error and topological error

TRAVERSING TOPOLOGY

Without looking at the picture, you can answer these questions from the table:

-where is node a (x,y coord)

-What polygon is P1 next to, and where are they adjacent.

-How do I traverse from node b to node a, then back again? (connectivity)

DIGITIZING

-When digitizing data for use in a GIS, you are building a topological representation of the data

Topological errors: imagine if line 3 never connected to node a. (now we don't have a closed polygon)

-imagine if line 2 was extended past node b (now there is nothing to the left/right of it).

To make your data work within a GIS, it should be topologically clean, and free of errors (Commands, Clear-Build).

One of most expensive GIS activities

Many diverse sources (source integration, data fusion, interoperability)

Two broad types of collection

-data capture direct

-Data transfer

Two broad capture methods

Primary (direct measurement)

-Raster = digital RS images and aerial photos

-Vector = GPS measurements and survey measurements

Secondary (indirect measurement)

-Raster = scanned maps, DEMS from maps

-Vector = Topographic surveys, toponymy datasets from atlases

Stages in Data Collection projects

Planning>Preparation>Digitizing/Transfer>Editing/Improvement>Evaluation>Planning>etc...

Capture specifically for GIS use

RASTER- RS

-ie. SPOT and IKONOS satellites and aerial photography

-passive and active sensors (RADAR-LiDAR)

Resolution is key consideration

-spatial

-spectral

-temporal

VECTOR

Surveying

-locations of objects determines by angle and distance measurements from known locations

-uses expensive field equipment and crews

-most accurate method for large scale, small areas

GPS

-collection of satellites used to fix locations on earth's surface

-differential GPS used to improve accuracy

Data collected for other purposes can be converted for use in GIS

Raster conversion

-scanning of maps, aerial photos, documents, etc

-important scanning parameters are spatial and spectral resolution

-raster to vector conversion can be done using a thematic map, and drawing lines around certain "themes"

Vector

-collection of vector objects from maps, photos, plans, etc

-digitizing (manual, heads-up vectorization)

-photogrammetry - the science and technology of meakingmeasurements from photographs

-ie measuring height of objects in an image

---usually multitasking

Buy vs Build is an important Q (some companies do nothing but sell data)

Many widely distributed sources of GI

Includes Geocoding

Key catalogs include:

-Geogratis.ca

-Geography Network

Access technologies (how you get the data)

-translation

-direct read (most GI companies do this)

Key Principles

-Clear plan, adequate resources, appropriate funding, and sufficient time

Fundamental tradeoff among

-quality, accuracy, speed, price

Two Strategies

-incremental (do little bits at a time (forest resources)

-Blitzkrieg - ie. mapping Columbia- lega/env/etc. all at once

Alternative resource options

-In-hourse (developing world cell phone bills)

-Specialist external agency (company)

A useful rule of thumb is that positions measured from maps are accurate to about 0.5m on the map

Map Scale/Ground distance

1:5000/2.5m

1:50000/25m

1:250000/125m

Positional Accuracy

-Within a DB the last four(?) digits in each UTMcoordinate would be questionable at 1:50000 scale

TESTING ACCURACY

Use an independent source of higher accuracy:

-find a larger scale map (smaller area)

-use precision GPS

Use internal evidence

-digitized polygons that are unclosed, lines that overshoot or undershoot nodes, etc. are indications or error.

-sizes of gaps, overshoots, etc. may be a measure of positional accuracy

-LOOK AT DATA!

Compute accuracy from knowledge of the errors introduced by different sources

-ie. 1mm in source document

-0.5mm in map registration for digitizing

-0.2mm in digitizing

-if sources combine independently, we can get an estimate of overall accuracy... (1² + 0.5² + 0.2²)^0.5 = 1.14mm.

Database- an integrated set of data (attributes) on a particular subject.

Geographic (spatial) database- db containing geographic data of a particular subject for a particular area (deodatabase)

Database management system (DBMS) - software to create, maintain and access databases.

A GIS links attribute and spatial data

Attribute data can come from a flat file (Spreadsheet) or database.

This is then linked to Map Data (point,line,area,topology, or theme file).

ADVANTAGES OF DBs

-avoids redundancy and duplication

-reduces data maintenance costs

-Faster for large datasets

-applications are separated from the data (applications persist over time, support multiple concurrent applications)

-better data sharing

-security and standards can be defined and enforecd

DISADVANTAGES
-expense

-complexity

-performance (esp. with complex data types)

-integration with other systems can be difficult

Hierarchical

Network (linkage but no hierarchy)

Relational (RDBMS) - old school

Object-oriented (OODBMS)

Object-Relational (ORDBMS)

Relational Databases rule now

-they can relate information from different files to discover new information

Software to create, maintain, and access databases

CHARACTERISTICS

Data model support for multiple data types

-ie. MS Access: Text, Memo, Number, Date/Time, Currency, AutoNumber, Yes/No, etc

Load data from files, databases and other applications

Index for rapid retrieval

Index for rapid retrieval

Query Language (SQL)

Security - controlled access to data (multi-level groups, ie. census, NGA)

Controlled update using a transaction manager

Versioning

Backup and Recovery

Applications

-forms builder

-report writer (data reports)

-Internet Application Server (available online data)

-CASE tools

Programmable API (Applications Program Interface)

-how we do it

ROLE OF DBMS

-Affect upwards

From Data > DBMS > GIS

DBMS Task: storage, indexing, security, query

GIS Task: data load, editing, visualization, mapping, analysis

Data stored as tuples (tup-el), conceptualized as tables (not REALLY tables)

Each tuple is an object that contains all the data

Allows more complex data to be incorporated

Used to create Tables

-two dimensional lists

-rows=objects

-columns=object states, properties, attributes

tupel= how data are held in reality (can't see it)

-openable in a text file.

This is most popular type of DBMS (over 95% is RDBMS)

Structured (Standard) Query Language - pronounced (SEQUEL)

Developed by IBM in 1970s

Now accepted standard for accessing relational databases

Three types of usage

1)stand alone queries (simple)

2)High level programming (ie. predict future, model)

3)Embeddd in other applications (basically GIS... dataset embeded into program)

TYPES OF SQL STATEMENTS

Data Definition Language (DDL)

-create, alter, and delete data

-create table, create index

Data Manipulation Language (DML)

-retrieve and manipulate data

-select, update, delete, insert

Data Control Laguages (DCL)

-Control security of data

-Grand, Create user, drop user

Fundamental query operation (in RDBMS)

Occurs because

-data created/maintained by different users, but integration needed for queries

Table joins use common keys (column values)

Table (attribute) join concept has been extended to geographic case.

The "join" is the new table, which contains information that has been found in two separate tables

relational field is the attribute that is found in more than one table

Quad tree: Points/Regions

-multi-resolution raster

-image compression

Quaternary Triangle Mesh

-Multi Scale (triangles within triangles).. levels

-Starting at prime meridian and equator

-recursive subdivision

-at 21 levels, cells are 1m

-solves many projection issues

-used with global imaging

-better geometry

Projections are really relevant anymore due to this.

Prime Meridian Cleaves through Royal Observatory

Digital earth projection

-not any better than QTM, just different

Hexagonal tesslation (splitting into pieces)

-subdivision based on vertex and centroid 'parents'

-zooming changes resolution

-efficient (area/speed)

-the computation here is more complex

vertex= more uiform project.. shapes confined to boundaries of parent hexagon

centroid = shape with pieces sticking out-  boundary of parent goes through other hexagons.

Minimum resolution is much greater detail than the massive triangles of QTM

overlay: a spatial retrieval operation that is equivalent to an attribute join. Overlay two spatial things to see something new, or see how thoese things interact.

buffering: a spatial retrieval around points, lines, or areas based on distance.

WHY USE?

Improve field productivity

-use maps to make decisions

-view location of real-time information

-route and navigate using maps

Maintain operational data

-inspect assets

-collect accurate locations

-capture observations

-record events

Facilitate accurate operational awareness

-real-time locations

-wireless synchronization

CHALLENGES
-Increase productivity of mobile workforce

-take information in and out of field

-many dif applications /w unique requirements

-rapidly changing technology

-tradeoffs (capabilities, price, size, ruggedness, weight, battery life)

DEVICES

-non-rugged handheld devices/smartphones

-high accuracy GPS devices

-rugged handheld devices

-rugged keyboard devices

-tablet PCs and in-vehicle devices

Out of the box mobile GIS application for field mapping

Extensive GIS and GPS tools

Target platforms are Windows Mobile 5/6 and Windows XP/Vista

TOOLS

View, and navigate GIS data

-vector/raster/StreetMap/photos/graphics

Collect new GIS features

Update and edit existing GIS fewatures

Edit inspection data

Search for GIS features

Use data capture devices

-GPS, rangefinders, cameras

Geocode and route using StreetMap

Use GPS for basic navigation

Synchronize with geodatabase via ArcGIS Desktop or ArcGIS Server

Very few programming requirements! (none for queries, basic data capture, and simple toolbars)

Tools such as GeoCollector are pre-loaded with ArcPad

ArcGIS Mobile compliments ArcGIS Server

-deploy maps and GIS tasks to mobil workers

-Rapid data collection and inspection workflows

-Included with ArcGIS Server Advanced Enterprise

ArcGIS Mobile consists of:

-Windows Mobile Application

-.NET 2.0 and Compact Framework Runtime

-ArcGIS Server mobile data web service

Visual Studio Software Development Kit

Task-driven user experience!

Tasks...

-view and navigate maps

-collect new GIS features

-update existing GIS features

-synchronize with GIS server

-Use GPS

-search for GIS features

-manage a work list

-check device status