GIS III

Fragen zur Vorlesung GIS III an der ETH bei Prof. Raubal Basierend auf der Zusammenfassung von Roland Schenkel. Karten sind ohne Grafiken ohne Interoperabilität

Fragen zur Vorlesung GIS III an der ETH bei Prof. Raubal Basierend auf der Zusammenfassung von Roland Schenkel. Karten sind ohne Grafiken ohne Interoperabilität


Set of flashcards Details

Flashcards 75
Students 11
Language English
Category Computer Science
Level University
Created / Updated 26.01.2012 / 08.08.2019
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SWE

Sensor Web Enablement

o Standards enable users to discover & access sensor data of a sensor Web or sensor network

o 2 XML-Schemas (SensorML, O&M)

o 4 Services (SOS, SAS, WNS, WPS)

GML

Geography Markup Language

o XML grammar defined by OGC to express geographical features.

o Modeling language for geographic systems as well as an open interchange format for geographic transactions on the Internet.

o Points, lines, polygons, …

KML

Keyhole Markup Language

o Acquired by Google in 2004.

o Official OGC standard in 2008

o XML-based file format for describing geographic features, including visualization.

o KML file usually specifies set of features (placemarks, images, etc.) in longitude / latitude; also defines „camera view‟ parameters.

o Often distributed in zipped KMZ files.

GEORSS

RSS (Really Simple Syndication): family of Web feed formats for publishing frequently updated information, e.g., news headlines.

o Simple, real-time; only a few XML-tags.

o GEORSS: standard for encoding location information in RSS and other XMLs

FE

OGC Filter Encoding: XML based spatial query language

o Usage in:

* OGC WFS GetFeature

* OGC SLD

* OGC CSW (Catalog Service for the Web)

o Operators provided:

* Comparison Operators

* Spatial Operators

* Logical Operators

What is Geo-Coding?

Attaching a unique quantitative location (footprint) to Named Entities

What is Geo-Parsing?

Geographic context embedded in natural language descriptions, Recognising geographic references with Named Entity Recognition (NER) from Natural Language Processing (NLP).

e.g.: 20 km northeast of Vegas => W???° N??°

What is Geo-Tagging?

Geo-Parsing + Geo-Coding => recognise geographic references in natural language descriptions an get the location of them

GIR?

Geographic Information Retrival, about 20 % of all Web-searches have a geographic context. => Find geo-specific resources on the Web:

What are LBS?

Location Based Services, deliver information to user based on her current location. Eg. Navigation and information services, Emergency services, Field applications, Geoservices for mobile phones, ...

What is the approach of LBS?

Subjectively weighted criteria, Integrating qualitative user preferences & multi-criteria decision analysis, Compensatory vs. non-compensatory decision rules (hard vs. soft rules), OWA (Ordered Weighted Averaging): Aggregate individual criteria to total evaluation score

Advantages and disadvantages of mobile GIS?

(+) Information capture and updating (e.g., acquire location information), Dissemination: mobile devices can bring GIS in the hands of billions // (-) Storage, Analysis, Presentation

Typical wireless communication channels for mobile GIS?

a) Bluetooth: For short-range communications (~10m), Application: communication between mobile device & GPC receiver, handset // 2) Wi-Fi (Wireless Fidelity), Typical range ~100m, Data transfer rate: ~10-54 MBps, Used to create WLAN (‘hot spots’), Limited spatial coverage // 3) Cellular networks, Type of radio network made up of radio cells, Each radio cell served by base station (fixed-location transceiver)., Cells cover different land areas. 3G: data transmission speeds up to 2 MBps; web surfing, video streaming, 4G: data transmission speeds up to 100 MBps

What is SWE?

a sensor Web is a system of wireless, intracommunicating, spatially distributed sensors that are deployed to monitor and explore environments, A sensor Web is a Web-accessible network of sensors and archived sensor data that can be discovered and accessed using standard protocols and APIs.

What is the Internet of Things?

Real-world objects (lights, cars, packages, etc.) are interlinked & connected to the

Internet. Location & status can be tracked. Network intelligent enough to self-organize information. Automatically respond to context, circumstances, or environment.

What is SOA?

Service oriented approach

Why SWE?

Enable interoperability not only within communities but between traditionally disparate communities!

Leverage benefits of open standards.

What is SLD?

Styled Layer Descripto, XML Language, extends the WMS standard to allow user-defined symbolization and coloring of geographic feature and coverage data.

Metdata, pros and cons of a distributed catalog?

[catalog doesn't store meta data] (-) Select from 100s of nodes, Gateway has to wait until slowest node responds, Difficult to sort results consistently. (+) up to date at every time

Metdata, pros and cons of a centralized catalog?

[catalog harvests the information and stores them local] (+) Each search against all records. Easily sorted globally, High performance. Metadata directly published via online metadata form. (-) not totally up to date

What is a Mashup?

a Web page or application that dynamically (≠ copy paste!) combines contents or functions from multiple Web sites: Live linkage to its sources!

What is a Geomashup?

a mashup where at least one of the contents/functions is georeferenced.

Architecture of Mashups?

Prior to 2005: server-side (due to performance), Nowadays: browser-side (better performance, JavaScript API’s released from Google etc.)

Structures of Mashups?

Basemaps // Operational layers: your own data published as service, results of queries, etc., respond to user actions, e.g., mouse click // Tools: business logic, analytical functions

Web Services vs. Browers-Side APIs? (Execution Location)

WebService: web servers, BSA: web browsers

Web Services vs. Browers-Side APIs? (Programming Language)

WebServices: independent of programming languages, can be used with any language. BSA: dependent of specific programming languages. APIs (eg. JavaScript, Flex, Silverlight) need to be used with corresponding language

Web Services vs. Browers-Side APIs? (Capabilities)

WebService: provide server-side functions, can operate databases, do not provide user interface or user interaction functions. BSA: provide browser-side functions, including user interface, user interaction, mouse control, brwoser-side logic, etc.

Web Services vs. Browers-Side APIs? (Relationship)

WebService: waiting to be called by browser-side API or other languages, BSA: usually encapsulate web services, especially RESTful Web services. Can call Web services based on user interaction, and let users use Web services without knowing it.

What is Web Scraping?

extracts information from unstructured Web content and transforms it into structured data

Important considerations for Mashups and Web Services?

1) Quality: can vary enormously; uncertainty / error can be propagated // 2) Copyright & terms of use // 3) Stability of mashup application depends on stability of its sources. // 4) Security: enterprise mashups can involve confidential information

What is SDI? And why to use it?

spatial data infrastructure. Geoportals reduce search time!

SOS

Sensor Observation Service.

Service um die Daten von den Sensoren zu erhalten und Sensoren zu steuern (Kamerarichtung)

SPS

Sensor Planing Service

Service um herauszufinden wo welche Sensoren sind und was sie können.

SAS

Sensor Alert Service

Service der Alarme der Sensoren speichert und wo man sich für Alarme anmelden kann.

WNS

Web Notification Service

Service provides asynchronous notification of sensor events (tasks, observation of phenomena).