The University of Chicago
Cartography Workshop
June 26, 2000, 9a.m. to noon.

Sandra Lach Arlinghaus, Ph.D.
The University of Michigan, Ann Arbor.
School of Natural Resources and Environment; College of Architecture and Urban Planning.
sarhaus@umich.edu; http://www.snre.umich.edu/~sarhaus;  http://www.imagenet.org
Community Systems Foundation, Ann Arbor.
Director, Spatial Analysis Division

 
  • Maps on the computer--an application of mathematics in geography:
    • Static maps:  maps on the World Wide Web and elsewhere.  Click here for sample.
    • Dynamic maps (maps that change when there is a change in the underlying database).  Geographical Information Systems (GIS).  Two desktop GISs:  compare and contrast them.  Generally, Atlas is based more on classical cartography than is ArcView; however, ArcView makes much greater use of the capability of the computer than does Atlas.
      • ArcView GIS (Environmental Systems Research Institute, ESRI)--open a map of the world.  Note the latitude and longitude read-out.  Default projection generally just a flat map.
        • Zoom-in tool:  magnifying glass with a plus sign in it.
        • Zoom-out tool, magnifying glass with a minus sign in it, or use a menu.
        • Distance tool:  distance from Chicago to Cape of Good Hope to Sri Lanka; shows individual distance for last leg of trip as well as accumulated distance, after the default flat map is projected to some standard projection--here the Robinson.
      • Atlas GIS (ESRI)--open a map of the world.  Note the latitude and longitude read-out.  Default projection is a Robinson projection.
        • Zoom-in tool:  magnifying glass with a plus sign in it.
        • Zoom-out tool, magnifying glass with a minus sign in it, or use a menu.
        • Distance tool:  distance from Chicago to Cape of Good Hope to Sri Lanka; shows individual distance for last leg of trip as well as accumulated distance.  (Distance used is great circle distance.)
    • Concepts:
  • Making GIS maps using onboard information and base maps--demonstration of thematic mapping.  Different methods of partitioning the data can lead to very different maps.  When considering a thematic map made by someone else, it is therefore important to consider how the underlying database might have been partitioned.
    • Quantiles--there are roughly the same number of observations in each interval but the size of the interval might vary.
      • With a map of the world in view, double click on the "legend" on the left (in ArcView).  A "legend editor" pops up.  Choose "graduated color" from the pull-down menu.  The default value colors each country a unique color (called "unique value").  Choosing "graduated color" will enable you to group countries with similar characteristics as one color.  The map will have a theme, such as the world's lands grouped by area.  Data about area will be grouped into ranges, or categories, by color (e.g. all countries of less that 1.6 million square miles are colored pink).
      • You will need to choose a classification field; that is, you will need to choose some set of data.  For example, choose "sqmi_cntry" or number of square miles in each country shown on the map.
      • Choose the classification method for the data.  That is, how is the information about area to be split into different categories?  One way is to choose by "quantile."
      • Notice now that back in the legend editor you can choose various color schemes; the default scheme is red monochromatic (different shades of red come up for different data ranges--pink for lower values, deep red for higher values).
      • Now, look at the map made using this process.  There are many countries in the deep red category that are visible on the map and none that are easily visible in the pink range.  This observation should not be surprising, but it should be noted.
    • Equal interval--the size of the interval is uniform but the number of observations within each interval might vary.
      • Repeat the steps above, but instead of choosing "quantile" as the method by which to partition data, choose instead "equal interval."
      • Look at the result back in the legend editor; keep the color scheme the same (red monochromatic).
      • Now, look at the map made using this process.  Compare and contrast the result with the map above.  Notice the importance of selecting a method for partitioning of data and its implication for resulting maps.  (Related reference:  Monmonier, How to Lie with Maps.)
    • Other methods of data partitioning and consequences for associated maps are available, as well, in most GIS packages.  Each has its own merits and drawbacks; each produces maps different from other data partitioning methods.
    • Concepts:
      • Partition--choose method according to data arrangement.
      • Coloring--no more than four colors are ever required to color a map in the plane.  Animated map of the U.S.A. using four colors (they were needed to distinguish adjacent states; adjacency along edges--not at corners).

Break
  • Making GIS maps bringing in custom information or base maps--demonstration.
    • Bringing in new data (in a spreadsheet) to use with on-board base maps--ESRI demographic data by nation.
      • Open up the map of the world.
      • Go to start up window and select the tables option.
      • Navigate to where desired spreadsheet is stored.  Click on "add" if it is active (otherwise, "new" and then later on "add").
      • New table (demog.dbf in this example) will then appear along with the map.  Click on the map to make the map window active (title bar turns blue).
      • Open the attribute table for the country theme in the map.  This is the table that came with the map and has all the key information about the map (such as perimeter, area, and such so that the map can be drawn).  Data in the new spreadsheet will be linked to the existing attribute table.  In order for it to link, there MUST be a column in the new spreadsheet that is has the same topic as a column in the attribute table.  That is, the content of the two columns should be on the same topic (the column headings need not be identical).  The two columns need not be identical but should have a common theme.
        • Identify the common column; in this case it is Abbrevname in demog.dbf and Cntry_name in the attribute file.  Both show country names--matches will be made where there is duplication between columns.
        • On the new spreadsheet, demog.dbf, click on the column heading; it becomes highlighted.
        • THEN, on the attribute table, click the corresponding column heading so that it becomes highlighted.  The order in which these two steps are executed is critical.  FIRST the new table, THEN the attribute table.
        • Now, notice the join button at the top (run the mouse over the buttons and callouts will tell you which one is the join button--if it is not active, try the sequence of steps again).  Click on it and the new table will disappear and become joined to the attribute table.
        • THUS, the situation of bringing in new data has now been reduced to the first situation of both onboard data and maps.  The map can now be colored using the new demographic data that has been successfully joined to the attribute table.  Here is a sample of a map colored according to total fertility rate.
    • Bringing in new maps that are already in electronic format--the Digital Chart of the World (DCW) as an example.  These maps show an unusual amount of detail.  The information is gathered from various aerial surveys.  There is information on the web and the capability to generate DCW maps on the web (look in any search engine or web guide).  A few DCW maps made in Atlas GIS are linked below.
    • DCW maps can be brought from Atlas to ArcView (as can other maps using a conversion package available on the ESRI website, www.esri.com).  The reason to convert the maps is to use the extra computing capability of ArcView.  Some contour maps (contour interval of 1000 feet) are converted to Triangulated Irregular Networks using ArcView.  Samples are shown below.
    • Bringing in new maps that are not already in electronic format
      • Heads-up, or on-screen, digitizing (drawing of maps)
        • Freehand drawing
            • Click on the drawing tool button on its lower right-hand corner; this action will expose a drop-down list of tools.  Choose the zigzag line (click on it).  Now move the cursor over into the map and click and draw.  This new polygon can be made into a layer of its own and can have data associated with it.  With such procedure done, then we are once again reduced to the state of simply manipulating onboard maps and data.
        • Tracing using a transparency (the "harsh environment" approach to digitizing)
            • Imagine that you have a photocopy on a transparency of what you would like to draw on the map.  Tape the transparency to the screen and use the cursor and the drawing tools above to trace the transparency from the underneath side.
        • Tracing using a scanned (raster) image (made up of pixels--little squares) underlay or an aerial photo.  Here the problem is usually to get the image to "register" properly with the map.  Knowing the projection of both is very useful in this regard so that the image and the map line up correctly.
            • There are extensions or plug-ins to software that allow one to use a raster image as a backdrop behind a vector (made of mathematical points) map and to draw on the map.
      • Digitizing using a digitizer--a substantial piece of equipment that gets plugged into the computer to mimic a computerized drafting table.  Trace on the table underlain with fine wires and the information gets sent to the computer to which the digitizer is attached.  Digitizers are particularly useful for maps that are too large to scan (physically cutting a map removes part of it).  In any digitizing there are tradeoffs between file size and curvature fidelity.
      • Global Positioning System (GPS) and satellite technology offer exciting, but perhaps expensive, sources for input.

 
USING GIS MAPS
  • Within a GIS. 
    • One way to use them is to analyze them further WITHIN the GIS.  Analysis of information using buffers.  Buffers are but one analytic tool; ArcView has a whole host onboard.
      • Good ideas endure, despite technology change (reference Mark Jefferson's work on "The Civilizing Rails"; link (from www.imagenet.org) to a reference about Jefferson's work).  The buffers can then be used in conjunction with other information.  How many major populated places lie within the 10 mile buffer? Close-up view.  Imagine using census data, by household to calculate, for example, how many households of one type or another lie within 50 km. of a hazardous waste site.  Often the analytic capabilities are limited (mostly) by data availability.
    • Use them in conjunction with remotely-sensed data (for example, counting the number of trees along a street (work of Katya Podsiadlo in NRE530, Fall, 1999, University of Michigan, School of Natural Resources and Environment, employing City of Ann Arbor maps and aerial photos--so that a city might have a count used in assessing developers funds to put in a street-tree escrow).
  • Outside a GIS. 
    • To get copies of GIS maps for use elsewhere:
      • Use the Windows-universal command, Alt+PrntScrn, to take what is on the screen, put it on the Windows clipboard, and paste it into other applications. 
      • Use the "save as" or "export" or "copying" capability of the GIS itself to make static maps that can be opened as images in other applications (sometimes, though, these capabilities that are internal to the GIS itself are not all that one might wish for; one example is in exporting images from ArcView that have patterns with transparent backgrounds--in this case it is better to use the command above).
    • Using GIS images elsewhere.
      • Adobe PhotoShop or other editor to create .gif or .jpg image from GIS maps.  Go to File|New to open a blank canvas.  Then use Ctrl+v to paste in the content of the Windows clipboard.
      • Web pages--create a simple one using Netscape.  Open any site using a recent version of Netscape.  Then, go to File|Edit Page.  Then, edit the page, much as you would in a word processor, save it, and talk to your local tech people to find out how to put it up on the web.
      • Clickable maps.  Take a map at a broad scale and link to it close-ups of regional maps, photos, or images of spreadsheets.  Link more to each of these.  A clickable map is a sort of spatial table of content to a broad range of graphic displays.  Here is a sample made by Jennifer Rennicks in NRE530, Fall, 1999 (click on the Cockscomb Basin Wildlife Sanctuary in the map).
      • Animated maps
        • Link to an article about animated maps, from the site: http://www.imagenet.org.  Animated maps can be quite useful in tracking diffusion or spatial change over time.
        • In ArcView, project the map of the world to the orthographic (world from space) view.  This map can be customized to be centered on various longitude values.  Save these views as .gif images in PhotoShop.  Assemble them in a .gif animator such as Gamani Movie Gear.
      • Useful in creating your own images to go with explanations, in Word for example, of how to use software (as above with the images of ArcView and Atlas GIS).

Resource CD.  This CD includes a wide variety of maps.  Some, such as the files in the GIS Maps folder, contain subnational boundaries by country and are suitable for use as base maps.  Others are simply images that may be useful as a base for a clickable map or for insertion into a Word document.  Yet others are files that can be loaded into ArcView.  This CD is distributed by the author free of charge and neither it, nor any of its files, are to be sold.


A few hard copy references are listed below.   Some are classical, some are contemporary.  Most authors have written a number of books on cartography.  These few are offered as entry points to the literature at various time periods.

Jefferson, Mark. The civilizing rails. Economic Geography, 1928, 4, 217-231.

Raisz, Erwin.  General Cartography.  New York:  McGraw-Hill, 1938 (and later by various publishers).

Robinson, Arthur H.  Elements of Cartography.  New York:  John Wiley and Sons, 1953 (and later; some recent versions with multiple authors).

Greenhood, David.  Mapping.  Chicago:  University of Chicago Press, 1964.

Robinson, Arthur H.  Early Thematic Mapping in the History of Cartography.  Chicago:  University of Chicago Press, 1982.

Harley, J. B. and Woodward, David.  The History of Cartography (multiple volumes).  Chicago:  University of Chicago Press, 1987.

Snyder, John P.  Flattening the Earth:  Two Thousand Years of Map Projections.  Chicago:  University of Chicago Press, 1993.

Sobel, Dava and Andrews, William J. H. The Longitude.  New York:  Walker and Company, 1995.

Monmonier, Mark S. and de Blij, Harm, How to Lie with Maps, 2nd Edition.  Chicago:  University of Chicago Press, 1996.

Puu, Tonu,  Mathematical Location and Land Use Theory.  Berlin and New York:  Springer Verlag, 1997.