TECHNOLOGY OF THE GEOSPATIAL WEB

ENVS 4522

2 Kinds of Web Maps

Static Web Maps

Data is pre-loaded

<A HREF="rollover_target.html"onMouseOver = "rollover('home')" onMouseOut = "rollout('home')" ><IMG SRC="../graphics/home_out.gif" NAME="home" ALT="Home Page" BORDER=0 HEIGHT=130 WIDTH=115></A><SCRIPT TYPE="text/javascript"><!--setrollover("../graphics/home_over.gif");//--></SCRIPT>

<?xml version="1.0"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="467" height="462"><!-- This is the red square: --><rect x="80" y="60" width="250" height="250" rx="20" fill="red"stroke="black" stroke-width="2px" /><!-- This is the blue square: --><rect x="140" y="120" width="250" height="250" rx="40" fill="blue"stroke="black" stroke-width="2px" fill-opacity="0.7" /></svg>

Stored in public directory

Dynamically Created Web Maps

General Software

• Webserver

• Geodatabase• Spatial data

• Map server

Dynamically Created Web Maps

Geoserver

<gml:Polygon><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>0,0 100,0 100,100 0,100 0,0</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon><gml:Point><gml:coordinates>100,200</gml:coordinates></gml:Point><gml:LineString><gml:coordinates>100,200 150,300</gml:coordinates></gml:LineString>

Mapserver

ArcIMS

Other types of web maps

• Distributed web mapsMaps are created from distributed data sources. The interface of the web mapping system provides a method to access maps on other servers.o http://www.openlayers.org/

• Real time web mapso Real time maps show the situation of a phenomena

as it is occurring.http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html

• Open, reusable web mapso Web maps in this category are usually more complex

web mapping systems that offer APIs for reuse in other people's web pages and products. An example for such a system with an API for reuse is Google Maps. http://developer.yahoo.com/maps/flash/index.html

Evolution: Transferring of Data

• The difference lies in how data is streamed from the provider to the user Over the Internet

Data Components of Web Maps

Vector

Raster

Vector VS Raster

• Neither is better

• The data you utilize depends on the purpose of the application

Vector VS Raster

• Vector data is an interpretation of the natural world

• Raster data is an actual representation of the natural world at a moment in time

Primary VS Secondary Data

• Primary Datao Data that the application is concerned abouto Main theme of the application

• Photoso http://www.iceburnslair.com/mapper/lv-

night/GMap.php

Primary VS Secondary Data

• Basemap Datao Supporting spatial data used to contextualize the

mapping application's theme.

o Basemap http://www.openstreetmap.org

Summary

• Web maps requireo Spatial Datao Software package to serve up the spatial datao A general plan as to the purpose of the

application