hawaii pacific gis conference 2012: internet gis - create your own google like maps

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Thursday, September 2, 2010 Create Your Own Google-like Maps Michael Baker Senior Consultant

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Page 1: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Create Your Own Google-like Maps Michael Baker

Senior Consultant

Page 2: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Why Build a Google-like Mapping Application?

Have you ever:

– Wanted your mapping application to have the same navigation as Google Maps?

– Wanted the same speed and performance as Google Maps?

– Wanted to see your vector data in Google Maps?

– Wanted to see your imagery in Google Maps?

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Page 3: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

History of Web Mapping: Pre - 2003

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History of Maps on the Web (2003)

Autodesk's M apGuide

ESRI's M ap Objects

TerraServer USA

Netscape browser

(M osaic)

Intergraph's GeoM edia

WebM ap 1.0

M apQuest

Java 1.0

The National Atlas of

Canada

Xerox PARC M apserver

HTM L 1.0

Birth of the WWW

HTTP 1.0

Flash Player 5

ESRI's ArcIM S 3.0

SVG 1.0

First web browser

1989 1991 1993 1995 1997 1999 2001 2003

Page 4: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

History of Web Mapping: 2003 – Present

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Maps on the Web 2003 to Present

Term Web 2.0 introduced

Windows Live Local

Google M aps API

Yahoo! M aps API

SVG 1.2

Firefox 1.5 (native SVG)

Google Earth

Google M aps

2003 2004 2005 2006 2007

Page 5: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

How Does Google Maps Work?

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Page 6: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Development History of Google Maps

Google Maps first started as a software application developed by Lars and Jens Rasmussen

for the company Where2.

In October 2004 the company was acquired by Google where it transformed into the web

application Google Maps.

The application was first announced on the Google Blog on February 8, 2005.

It originally only supported users of Internet Explorer and Mozilla web browsers, but support

for Opera and Safari was added on February 25, 2005.

Currently Internet Explorer 6.0+, Firefox 2.0+, Safari 3.1+, and Google Chrome are supported.

It was in beta for six months before becoming part of Google Local on October 6, 2005.

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Page 7: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Performance - It Is All About the Cache!

The map within Google Maps consist as a set of tiles

These tiles cover the entire earth at each zoom level

Tiles exist for each map type:

– Street map

– Satellite map

– Hybrid map

– Physical map

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Page 8: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

How Much Cache?

Tiles do not cover all regions at all zoom levels

Different areas of the map may contain tiles at varying resolutions and therefore varying zoom

levels

Tile coverage of any map type varies based on location

– For example, many areas of the Pacific Ocean do not appear at high zoom levels, while Honolulu may

have very detailed maps

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Page 9: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Zoom Levels

At the lowest zoom level (0), one tile represents the entire earth

Each succeeding zoom level divides the map into 4N tiles, where N refers to the zoom level

– Zoom level 1, divides the world up into a 2x2 grid for a total of 4 tiles

– Zoom level 2, divides up the world into a 4x4 grid for a total of 16 tiles

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Page 10: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Spherical Mercator

The coordinates in Google Maps and which are presented to the users is Latitude/Longitude

in WGS84 Datum

For tile publishing, a Mercator projection is used.

Why Mercator?

– Mercator projection significantly distorts scale and area

– It has two important properties:

It is a conformal projection

– Preserves the shape of relatively small objects

It is a cylindrical projection

– North and south are always straight up and down, and west and east are always straight left and

right

Since the Mercator projection goes to infinity at the poles, it does not actually show the entire

world.

– Maximum latitude is approximately 85.05 degrees

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Page 11: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Addressing Tiles

There are three coordinate systems that Google uses:

– Pixel coordinate referencing a point on an image tile

– Tile coordinates referencing a tile within a tile layer

– The zoom layer, which defines the total number of tiles

This is often referred to as Google XYZ

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Page 12: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Why Would You Not Use Google?

Why as a website developer, who controls all aspects of your site, would you allow a big alien

blob on your site?

– You accept whatever colors, fonts and map layers Google chooses

– You do add some custom markers and overlays but fundamentally, the map itself is out of your hands

Google’s choices about what to display on the map may not work for your application

You are limited to Google API’s terms and conditions

You are limited to what Google wants to implement

You so have much invested in your data

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Page 13: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

If Not Google Maps, What?

The key is to understand the map

stack

Modern online mapping applications

adhere to this architecture

There are four major components of

the map stack:

– Browser UI

– Tile Cache

– Map Server

– Geospatial data

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Geospatial

Data

Map Server

Tile Cache

Browser UI

HTTP Server

Tile Server

Application Server

Page 14: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Tile Cache

A tile cache is a server that sits between the browser and the map server.

It checks to see if a requested map tile is already generated so it can be served up quickly.

If the map tile is not already generated, the tile cache gets it from the map server and saves it

for future requests.

The tile cache may be considered as one half of a layer in the map stack.

It is not technically required.

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Page 15: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Map Server

A map server is an application that takes geospatial data as input and renders graphical

output.

The map server allows the user creative control of the final map.

Map servers can be exposed directly to the internet or can be hidden from direct access by

the tile cache layer in the stack.

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Page 16: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Geospatial Data

The building blocks of any mapping application are the databases that define the points, lines,

and polygons that represent real-world places, roads, and areas.

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Page 17: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

How Do I Create a Google Maps-like Application

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Page 18: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Performance – Need Cache

Map caching is a very effective way to make maps run faster.

When you create a map cache, the server draws the entire map at several different scales,

and stores copies of the map images.

The server can then distribute these images whenever someone asks for a map.

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Page 19: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Tile Caching Review

Advantages

– Performance

– Quality

Performance isn’t affected by how much detail is on the map

– Industry standard

Tile caching is becoming an industry standard

Disadvantages

– Takes time to generate the tiles

When should you cache?

– If the data you see on the map needs to be live, with no time delay acceptable, then caching is not

appropriate.

Although the cache represent pictures of the data, you can still run operations on your map

and your data.

These operations will query the server and return the results.

Results will be drawn on top of the cached image.

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Page 20: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Thinking about Cache

Need to think about the layers of the map

Design your map for the scale to be viewed.

Utilize the style properties at each scale.

Choose your largest scale carefully. This will show the most detail and take the longest to

process.

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Page 21: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Utilize Open Source Tools

Remember the map stack

– Browser UI

– Tile Cache

– Web Server

– Geospatial Data

There are a couple of commercial /

open source tile caching solutions

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Geospatial

Data

Web Server

Tile Cache

Browser UI

HTTP Server

Tile Server

Application Server

Page 22: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Summary

Google Maps is a great application. However, it has limitations.

Organizations have spent a tremendous amount of money collecting and maintaining their

data.

It is not difficult to create your own Google-like mapping application.

The key is to understand the elements of the map stack.

Remember scale and layer definitions.

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Page 23: Hawaii Pacific GIS Conference 2012: Internet GIS - Create Your Own Google Like Maps

Thursday, September 2, 2010

Questions?

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