Table of Contents for
OpenLayers 3 : Beginner's Guide

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition OpenLayers 3 : Beginner's Guide by Erik Hazzard Published by Packt Publishing, 2015
  1. Cover
  2. Table of Contents
  3. OpenLayers 3 Beginner's Guide
  4. OpenLayers 3 Beginner's Guide
  5. Credits
  6. About the Authors
  7. About the Reviewers
  8. www.PacktPub.com
  9. Preface
  10. What you need for this book
  11. Who this book is for
  12. Sections
  13. Time for action – heading
  14. Conventions
  15. Reader feedback
  16. Customer support
  17. 1. Getting Started with OpenLayers
  18. Advantages of using OpenLayers
  19. What, technically, is OpenLayers?
  20. Anatomy of a web mapping application
  21. Connecting to Google, Bing Maps, and other mapping APIs
  22. Time for action – downloading OpenLayers
  23. Time for action – creating your first map
  24. Where to go for help
  25. OpenLayers issues
  26. OpenLayers source code repository
  27. Getting live news from RSS and social networks
  28. Summary
  29. 2. Key Concepts in OpenLayers
  30. Time for action – creating a map
  31. Time for action – using the JavaScript console
  32. Time for action – overlaying information
  33. OpenLayers' super classes
  34. Key-Value Observing with the Object class
  35. Time for action – using bindTo
  36. Working with collections
  37. Summary
  38. 3. Charting the Map Class
  39. Time for action – creating a map
  40. Map renderers
  41. Time for action – rendering a masterpiece
  42. Map properties
  43. Time for action – target practice
  44. Map methods
  45. Time for action – creating animated maps
  46. Events
  47. Views
  48. Time for action – linking two views
  49. Summary
  50. 4. Interacting with Raster Data Source
  51. Layers in OpenLayers 3
  52. Common operations on layers
  53. Time for action – changing layer properties
  54. Tiled versus untiled layers
  55. Types of raster sources
  56. Tiled images' layers and their sources
  57. Time for action – creating a Stamen layer
  58. Time for action – creating a Bing Maps layer
  59. Time for action – creating tiles and adding Zoomify layer
  60. Image layers and their sources
  61. Using Spherical Mercator raster data with other layers
  62. Time For action – playing with various sources and layers together
  63. Time For action – applying Zoomify sample knowledge to a single raw image
  64. Summary
  65. 5. Using Vector Layers
  66. Time for action – creating a vector layer
  67. How the vector layer works
  68. The vector layer class
  69. Vector sources
  70. Time for action – using the cluster source
  71. Time for action – creating a loader function
  72. Time for action – working with the TileVector source
  73. Time for action – a drag and drop viewer for vector files
  74. Features and geometries
  75. Time for action – geometries in action
  76. Time for action – interacting with features
  77. Summary
  78. 6. Styling Vector Layers
  79. Time for action – basic styling
  80. The style class
  81. Time for action – using the icon style
  82. Have a go hero – using the circle style
  83. Multiple styles
  84. Time for action – using multiple styles
  85. Style functions
  86. Time for action – using properties to style features
  87. Interactive styles
  88. Time for action – creating interactive styles
  89. Summary
  90. 7. Wrapping Our Heads Around Projections
  91. Time for action – using different projection codes
  92. Time for action – determining coordinates
  93. OpenLayers projection class
  94. Transforming coordinates
  95. Time for action – coordinate transforms
  96. Time for action – setting up Proj4js.org
  97. Time for action – reprojecting extent
  98. Time for action – using custom projection with WMS sources
  99. Time for action – reprojecting geometries in vector layers
  100. Summary
  101. 8. Interacting with Your Map
  102. Time for action – converting your local or national authorities data into web mapping formats
  103. Time for action – testing the use cases for ol.interaction.Select
  104. Time for action – more options with ol.interaction.Select
  105. Introducing methods to get information from your map
  106. Time for action – understanding the forEachFeatureAtPixel method
  107. Time for action – understanding the getGetFeatureInfoUrl method
  108. Adding a pop-up on your map
  109. Time for action – introducing ol.Overlay with a static example
  110. Time for action – using ol.Overlay dynamically with layers information
  111. Time for action – using ol.interaction.Draw to share new information on the Web
  112. Time for action – using ol.interaction.Modify to update drawing
  113. Understanding interactions and their architecture
  114. Time for action – configuring default interactions
  115. Discovering the other interactions
  116. Time for action – using ol.interaction.DragRotateAndZoom
  117. Time for action – making rectangle export to GeoJSON with ol.interaction.DragBox
  118. Summary
  119. 9. Taking Control of Controls
  120. Adding controls to your map
  121. Time for action – starting with the default controls
  122. Controls overview
  123. Time for action – changing the default attribution styles
  124. Time for action – finding your mouse position
  125. Time for action – configuring ZoomToExtent and manipulate controls
  126. Creating a custom control
  127. Time for action – extending ol.control.Control to make your own control
  128. Summary
  129. 10. OpenLayers Goes Mobile
  130. Using a web server
  131. Time for action – go mobile!
  132. The Geolocation class
  133. Time for action – location, location, location
  134. The DeviceOrientation class
  135. Time for action – a sense of direction
  136. Debugging mobile web applications
  137. Debugging on iOS
  138. Debugging on Android
  139. Going offline
  140. Time for action – MANIFEST destiny
  141. Going native with web applications
  142. Time for action – track me
  143. Summary
  144. 11. Creating Web Map Apps
  145. Using geospatial data from Flickr
  146. Time for action – getting Flickr data
  147. A simple application
  148. Time for Action – adding data to your map
  149. Styling the features
  150. Time for action – creating a style function
  151. Creating a thumbnail style
  152. Time for action – switching to JSON data
  153. Time for action – creating a thumbnail style
  154. Turning our example into an application
  155. Time for action – adding the select interaction
  156. Time for action – handling selection events
  157. Time for action – displaying photo information
  158. Using real time data
  159. Time for action – getting dynamic data
  160. Wrapping up the application
  161. Time for action – adding dynamic tags to your map
  162. Deploying an application
  163. Creating custom builds
  164. Creating a combined build
  165. Time for action – creating a combined build
  166. Creating a separate build
  167. Time for action – creating a separate build
  168. Summary
  169. A. Object-oriented Programming – Introduction and Concepts
  170. Going further
  171. B. More details on Closure Tools and Code Optimization Techniques
  172. Introducing Closure Library, yet another JavaScript library
  173. Time for action – first steps with Closure Library
  174. Making custom build for optimizing performance
  175. Time for action – playing with Closure Compiler
  176. Applying your knowledge to the OpenLayers case
  177. Time for action - running official examples with the internal OpenLayers toolkit
  178. Time for action - building your custom OpenLayers library
  179. Syntax and styles
  180. Time for action – using Closure Linter to fix JavaScript
  181. Summary
  182. C. Squashing Bugs with Web Debuggers
  183. Time for action – opening Chrome Developer Tools
  184. Explaining Chrome Developer debugging controls
  185. Time for action – using DOM manipulation with OpenStreetMap map images
  186. Time for action – using breakpoints to explore your code
  187. Time for action – playing with zoom button and map copyrights
  188. Using the Console panel
  189. Time for action – executing code in the Console
  190. Time for action – creating object literals
  191. Time for action – interacting with a map
  192. Improving Chrome and Developer Tools with extensions
  193. Debugging in other browsers
  194. Summary
  195. D. Pop Quiz Answers
  196. Chapter 5, Using Vector Layers
  197. Chapter 7, Wrapping Our Heads Around Projections
  198. Chapter 8, Interacting with Your Map
  199. Chapter 9, Taking Control of Controls
  200. Chapter 10, OpenLayers Goes Mobile
  201. Appendix B, More details on Closure Tools and Code Optimization Techniques
  202. Appendix C, Squashing Bugs with Web Debuggers
  203. Index

Tiled versus untiled layers

We mentioned earlier that there are two types of raster layers: tiled and untiled.

Before sharing ideas about tiling, the first thing to do is define tiling. According to Wikipedia, https://en.wikipedia.org/wiki/Tiled_rendering, it can be considered as the process of subdividing an image by regular grid.

So, why is this needed? Again, like for Closure Tools, it's for web performances. You can review about Closure tools in more detail in Appendix B, More details on Closure Tools and Code Optimization Techniques. Raster data and layers are built from other images or from vector data. The idea here with tiles is to balance the time for data processing and the time for transferring the resource (the image) through the network. It's also because using a regular tile grid can be cached, both by the browser and by the server.

Imagine that you require a complex layer. Would you want to wait for five minutes until it renders? (Rendering is the process to generate an image from geographic sources).

The following table shows a summary of pros and cons for using tiled, untiled resources:

Type of layer

Pros

Cons

Raster tiled layer

  • Speed: It only takes time to transfer an image.
  • Stability: You don't need a backend after tiles generation, only to host web accessible map images files.
  • Support for heavy load: Each tile is only a small image, which is light and will not overload your browser.
  • Tiles URLs are predefined; so, these can be served through CDN.
  • Heavy server consumption to preprocess (generate) the tiles.
  • Loss of render freshness if pregenerated and not associated with a tile server.
  • Heavy disk space consumption (Terabytes for world) when pregenerated tiles.
  • Visual break effects when continuous zoom because tiles are conceived with view levels in mind. When you are not using the view levels, images will stretch and would seems blurry.
  • Limited to serve multiple projections: a tileset has to be generated for each projection.

Raster untiled layer

  • Render freshness in all cases.
  • Limited disk space consumption.
  • Support for multiple projections.
  • Image quality rendering at all scales and not only defined levels.
  • Heavy load on server-side when there are a lot of users.
  • Slow with complex layering (heavy process time).

To summarize, if you want performance with less flexibility, choose tiled raster, and if you need fresh data and your layers are based on one or two data sources, choose untiled raster. You can also make a mix of both solutions: use tiles at some levels and untiled content at other levels. Another difference we don't really show in the table for tiles, is that you can pregenerate image tiles for an upper level (such as the country level or lower) and choose to generate tiles on the fly only for lower levels (the street level). Depending on the context, you don't choose: you have to connect to a third-party map server where the choice is restricted to the available web services / images.

The purpose of this comparison is to help you understand how to make a good decision concerning the required layers you have to choose. OpenLayers 3 is only a client-side library; however, knowledge about the principle to provide layers is a requirement to use it well. Also, you may need to host, or own, your map server to serve raster data.

Note

If you ever need to serve your own tiles or raster data, you can take a look at the following open source software:

Geoserver: http://geoserver.org

It is a server software that allows you to serve maps and data from a variety of formats to standard clients such as web browsers and desktop GIS programs.

Mapnik: http://www.mapnik.org

It's a toolkit for rendering beautiful maps, with clean, soft feature edges provided by quality anti-aliasing graphics, intelligent label placement, and scalable, SVG symbolization. Most popularly, Mapnik is used to render the OpenStreetMap main map layers.

Mapserver: http://www.mapserver.org

It is an open source geographic data rendering engine written in C. Beyond browsing GIS data, MapServer allows you to create geographic image maps, that is, maps that can direct users to web content. Like GeoServer, it allows map publications via Open Web Standards.

Degree: http://www.deegree.org/

Degree is open source software for spatial data infrastructures and the geospatial web. It shares with GeoServer and Mapserver the ability to serve map via Open Web Standards.

We can also mention that there are map proxy applications such as MapCache http://mapserver.org/mapcache/, GeoWebCache http://geowebcache.org, or MapProxy http://mapproxy.org.

Their important purposes are creating tiles for dynamic web server, caching requested map images using GeoServer, MapServer, Mapnik, Degree, or any other map servers.