Transcript GIS zeng

Presented by:
Yining Zeng
GIS technologies and Web
Mapping Services
Geographic information system
 Integrate, store, edit, analyze, share, display
geographic information.
 Create interactive queries, analyze spatial information,
edit data, maps and present the results.
Techniques used in GIS
 Data creation: digitization
 Data representation
 Raster: digital image represented in grids
 Vector: points, lines, polygons
 Non-spatial data: attributes
 Spatial analysis
 Data modeling, topological modeling, map overlay,
geostatistics
 Geocoding
 Web API
 API: application programming interface.
 GIS APIs are designed to manage GIS data for its delivery to
a web browser client from a GIS server.
Geocoding & Reverse geocoding
 Geocoding: interpolating spatial locations (X,Y
coordinates) from street addresses or any other
spatially referenced data such as ZIP Codes, parcel lots
and address locations.
Examine address ranges along a road segment
Various algorithms are used to help with address matching
when the spellings of addresses differ.
 Reverse geocoding: returning an estimated street
address number as it relates to a given coordinate
Web mapping
 Web mapping is the process of designing,
implementing, generating and delivering maps on the
World Wide Web.
 Web GIS: emphasis on analysis, processing of project
specific geodata and exploratory aspects.
 Mobile web mapping: using mobile computing
devices, can provide location sensitive information.
 Challenges: low display resolution, limited bandwidth,
copyright, security, reliability, technical complexity.
Types of web maps
Web mapping technologies
Server side technologies
 Web server: responsible for handling http requests by
web browsers and other user agents.
CGI: (common gateway interface)
Scripting language: PHP, Perl ,ASP, python
 Web application server: a middleware that connects
various software components with the web server and
a programming language
Web mapping technologies (Cont.)
 Spatial database: usually object relational databases
enhanced with geographic data types, methods and
properties.
PostGIS, MySQL, Oracle Spatial etc.
 WMS server: specialized web mapping servers
implemented as a CGI application, Java Servlet or
other web application server.
Client side technologies
 Web browser: support the display of HTML and raster
images (JPEG, PNG and GIF format).
 ECMAScript support: the standardized version of JavaScript. It is
necessary to implement client side interaction, refactoring of the
DOM of a webpage and for doing network requests. ECMAScript is
currently part of any modern web browser.
 Events support: mouse events, keyboard events, state
events, mutation events,SMIL animation events, UI events,
SVG specific events.
 Network request: get and post http requests and
provides some feedback on the data loading state.
Client side technologies (Cont.)
 DOM support: The Document Object Model provides
a language independent API for the manipulation of
the document tree of the webpage. DOM support
together with scripting is also known as DHTML or
Dynamic HTML.
 SVG support or SVG image support: integrates
vector graphics, raster graphics and text. Also supports
animation, internationalization, interactivity, scripting
and XML based extension mechanisms.
Client side technologies (Cont.)
 Java Support: The Java2D and Java3D libraries provide
2d and 3d vector graphics support. The creation of Java
based web maps requires Java support.
 Web browser plugins:
Adobe Acrobat – provides vector graphics and high quality printing
support.
Adobe Flash – provides vector graphics, animation and multimedia
support.
Apple Quicktime – Adds support for additional image formats, video,
audio and Quicktime VR (Panorama Images).
Adobe SVG viewer – provide SVG 1.0 support for web browsers
Sun Java plugin provides support for newer and advanced Java Features.
Google Maps Interface
Google Maps
 Google Maps website
 Google Maps API
 Street View
 Satellite images
 Geocoding capability
 Traffic information: include real-time traffic flow
conditions to the maps major cities of the United
States.
 Driving direction
Implementation
 JavaScript
 Ajax:
 XMLHttpRequest object
 Hidden Iframe
 JSON for data transfer
 The GIS data used in Google Maps are provided by
Tele Atlas, NAVTEQ, MapABC.
Yahoo! Maps
Comparison
Project
 Multimedia data stream model of aircraft
 Define data stream: Si, data rate, type(Micon)
 Aircraft(frame-number, time-stamp, one-frame-of-
video-data, type-of-aircraft)
 Define parameters for the continuous query:
Ci(cost),ri(average response time),Ri(output rate)
 Run a m-CQ manually