CS 128/ES Lecture 3a1 Map Types

CS 128/ES Lecture 3a2 Two Related Hierarchies Data Information Knowledge Input Process Output Question: When do we process the Data into Information or Knowledge?

CS 128/ES Lecture 3a3 Early Processing Compute your answers early and then reveal them when asked. Commonly done for systems such as search engines

CS 128/ES Lecture 3a4 Late Processing Store only your data; compute answers as needed MapQuest does this, as requests can’t be known in advance

CS 128/ES Lecture 3a5 Hybrid Do some processing early, do some late It is usually hard to detect that this is happening “Caching” is one (not so good) example of this approach. (Not so good because caching isn’t really processing, per se)

CS 128/ES Lecture 3a6 About the Output GIS’s have two main types of output Reports Maps As always, these can be combined

CS 128/ES Lecture 3a7 Reports A Geographic Information System is, at its core, a database. Good database software always has a report generator. Ergo, one can produce reports from a GIS On the theory that we already know how to write well, reports are relatively uninteresting to us as students – however vital they may be to real world concerns

CS 128/ES Lecture 3a8 Maps (and map types) The cartographer must make certain fundamental decisions about what to include on the map. Choices include Selection – what data to include Simplification – what data to combine Symbolization – how to show that data

CS 128/ES Lecture 3a9 A Spectrum How “processed” is the data? Not at all Some Lots Image Maps Line MapsCartograms

CS 128/ES Lecture 3a10 Image maps Composed of images of the area under study (usually aerial photos) Often pieced together to make “mosaics”

CS 128/ES Lecture 3a11 Advantages of image maps What you see is what is there (assuming the photo is current)

CS 128/ES Lecture 3a12 Problems with Image Maps Interpretation Details can be tricky – perspective is unusual Distortion Especially near edges and seams No annotation

CS 128/ES Lecture 3a13 Line Maps Reality is replaced by “reality-based” renderings “Raw” data is replaced by a representation of that data

CS 128/ES Lecture 3a14 Advantages of Line Maps Can concentrate on information “of interest” “Easy” to understand

CS 128/ES Lecture 3a15 Disadvantages of Line Maps Data is not as accurate due to: Incompleteness Representation (especially scaling) Deliberate “editorial” changes (see Exaggeration from previous lecture)

CS 128/ES Lecture 3a16 Cartograms Similar to line maps, but geographic data is deliberately distorted to make some other point

CS 128/ES Lecture 3a17 Utility of Cartograms Strengths Highlight exactly what is desired Strong visual imagery Weaknesses Not useful outside initially intended domain Relatively difficult to produce Lots of information is lost

CS 128/ES Lecture 3a18 Other types It is not uncommon to combine some of these types Cartographically Enhanced Image Maps are particularly common For example, the map we use in lab

CS 128/ES Lecture 3a19 Map Forms Historically, maps have been static, e.g. on sheets of paper Computer technology has rendered maps dynamic, i.e. interactive

CS 128/ES Lecture 3a20 Two “dynamic” maps

CS 128/ES Lecture 3a21 Question To what degree do Quake and other first person “shoot ‘em up” games provide “dynamic maps”? What about the “maze” screen saver?

CS 128/ES Lecture 3a22 Conclusions Many types of maps with varying degrees of “reality” attached There are tradeoffs between completeness of information and ease of user processing The ultimate arbiter is the user