A Summary of Some Key Points from Chapters 1 and 2 of Peterson

On page 1 Peterson indicates that “The Internet was revolutionary for maps, similar to the invention of printing.” Do you agree or disagree with this statement and why?

Chris Perkins made the following statement: "Arguably the most significant change in the whole of the history of cartography began only in the middle of the first decade of the twenty-first century. Characterized by some as ‘‘crowdsourcing,’’ and by others as Volunteered Geographic Information (VGI), this phenomenon centres on using the Internet to create, share, and analyse geographic data…” Do you agree or disagree with this statement and why?

Cartographic Communication vs. Geovisualization

Cartographic Communication We presume that we wish to communicate some spatial information to map readers. Typically, one map is produced. An example might be a map for a journal or newspaper.

A Model for Cartographic Communication

Geovisualization Geographic visualization is a private activity in which unknowns are revealed in a highly interactive environment. (MacEachren 1994)

MacEachren ‘s (1994) cartography-cubed representation of how maps are used

Alaska Vote on the Oil Measure: An Example of Geovisualization?

Geovisual Analytics Uses the computational power of computers and the visualization power of humans to make sense out of large geospatial datasets.

Redistricting: A simple example of geovisual analytics

Goal of redistricting is to equalize voter representation while trying to create compact districts…

Peterson notes that MapQuest held the greatest market share among mapping sites until 2009 when it was replaced by Google Maps. How are you getting directions today? What role do you see paper atlases playing in the future?

Raster vs. Vector Maps

Raster maps: the image is represented as a grid of “picture elements” called pixels.

Raster Graphic File Formats GIF (Graphics Interchange Format) Limited to 256 shades or colors An early standard for distributing graphic files Well suited for graphics composed of lines Often used with map animations

Raster Graphic File Formats JPEG (Joint Photographics Experts Group) 16.8 million colors are possible Red, green, and blue colors are combined at each pixel Each color is represented by 1 byte (where does the 16.8 million come from?) Most common Internet graphic format Incorporates image compression methods that reduce file sizes Best suited for pictures (not maps)

JPEG Compression

Raster Graphic File Formats PNG (Portable Network Graphics) Also can display 16.8 million colors Uses a lossless form of data compression Appropriate for mapping

Vector maps: Define a graphic using X and Y coordinate pairs; a vector-to-raster conversion must be used to display the vector database on a raster device. MapQuest Zoom Levels

Vector Graphic File Formats (Proprietary) PDF (Adobe’s Portable Document Format TM ) Based on the programming language Postscript TM PDF is of course used for more than graphics Adobe’s Flash Files are only a fraction of those for PDF Frequently used for creating mapping apps Adobe Flex is an associated development environment for creating Web apps

Vector Graphic File Formats (Open) SVG(Scalable Vector Graphics) Created by the World Wide Web consortium Based on the extensible markup language (XML) Used in Wikimedia Commons, the graphic library of Wikipedia File sizes are larger than for PDF and Flash

Raster vs. Vector on the Internet What are the advantages and disadvantages of using raster vs. vector maps?

Part a of Exercise #1 Use the Web to search for four maps that illustrate various types of graphic files: GIF, JPG (or JPEG), PNG, SVG, and PDF How to find these maps?

To prepare for Exercise #1 Read Chapters 3 and 4 in Peterson Sign up for the web hosting service described on pp of Peterson. Become familiar with online material for working with html (e.g., w3schools.com)

Tiled Web Maps Google Maps revolutionized online mapping via the multi-scale, panable (MSP) map With image tiling, the map is divided into tiles and these tiles are sent individually

Tiled Web Maps (cont.) Asynchronous Javascript and XML (Ajax) maintains a continuous connection with the server, exchanging small messages in the background even when the user has not made a request.

Cost of Map Storage

Question: If the Internet TCP/IP protocol splits data into packets, why do we also need map tiles?

Map Mashups A mashup is the melding of data and mapping tools to create new presentations of information. Note the Peterson quote: “Probably the most important development in mapping during the first decade of the 21 st century was the introduction of online tools in the form of the application programming interface (API).” Do you agree?

Animated maps are maps that are characterized by continuous change while the map is viewed. Peterson and Wendel’s Animated Atlas of Flight Traffic over North America as an example Animated Maps

Images on slides 4, 16, 19, 21, and 29 are from the web site for Peterson’s bookweb site for Peterson’s book Images on slides 7 and 9 are from the web site for Slocum et al.’s bookweb site for Slocum et al.’s book