GEOG 104
Compare Four Online Maps

OBJECTIVE: In this exercise, you are to compare the street network contents of four maps (really databases), for a place that you know well, as represented in several current on-line mapping services:

The primary focus should be to compare the factual contents. Do the maps (databases) show similar contents and do they agree with each other and with your experience/knowlege? What kinds of information does each map show? (Like streets, placenames, landmarks, streams, waterbodies, elevations, topography, scale, grid or latitude and longitude coordinates, north/orientation, etc.) And then, do they all agree? I.e., are the street names, shapes and connectivity the same on all of the maps? Look closely.

Secondarily, you may notice differences in the interfaces, the tools provided to aid the user, and the graphic design of the displays and symbols, that would affect the utility in any given context.

One might expect these differences to reflect the intended use of the maps.

Several On-Line Maps

The National Map Viewer

http://viewer.nationalmap.gov/viewer/ a web interface to maps from USGS data.

Hints... Overlays. Clear Map. Pan buttons. GIS Toolbox. "Base Map", "Imagery", and "Blank" buttons.

Open Street Map

http://www.openstreetmap.org/ offers maps and data based on user contributed information.

Hints... "Zoom and hand drag pan" to select the area. "Export" Tab, select either the Mapnik or the Osmarender Image, and the PNG or JPG format. Note that you have bounding rectangle and scale (as a representative fraction like 1:27500) on screen here. Hit the "Export" button. It should return an image file that you can save or cut and paste from your browser.

Googe Maps

http://www.maps.google.com/ offers maps based on Google's database of geographic features.

Hints... "Zoom and hand drag pan" to select the area. "Print" link. Toggle Satelite vs Map vs Terrain etc.

Yahoo Maps

http://maps.yahoo.com/ offers printable maps based apparently on Navteq's data.

Hints... "Zoom and hand drag pan" to select the area. "Print" "send" and "Save" links. Map, Hybrid, Satellite buttons. Meta-map navigation. Latitude and Longitude in the URL.

Google Earth

Google Earth seems to have a different set of street data than does Google Maps. Do they talk with each other?

Hints... GE requires a download and install and may be getting ahead of ourselves but, if you are game or already using it... turn on the "Roads" layer, leave the others off, and see what it shows you. Don't be fooled by waht you can see in the image data, look for their vectors.

Apple Maps

In 2012 Apple rolled-out a go-it-alone mapping system (kicking-out Google) and users were disappointed. Since then, Apple changed project managers, bought mapping technology (TomTom, Embark, HopStop, Locationary, etc) and maybe onto something. Those of you with iphones may want to see how it stacks up.

Assignment Tasks & Strategy Hints:

  1. Choose a small area (neighborhood) with which you are familiar, maybe your hometown or your current neighborhood.
  2. "Zoom-in" to that same area using the websites to compare maps of approximately the same scale and coverage. (I.e., have the maps to show the same geographic area in the same screen area.)
  3. Work with comparable scales, probably something larger than 1:24,000, maybe 1:10,000 or (better), "zoomed-in" far enough that the streets are labled.
  4. Compare the maps for content. See above.
  5. Print each of the maps (if you can, maybe via screen grabs or saving them as image files) and mark on them to illustrate where you spot differences. (I'm not sweating whether you have a color printer or not, you needn't either.)
  6. Write a brief (~1 page) report on what you found. Include the placename, the latitude and longitude, and the approximate scale of the maps, along with the differences and similarities you note among the different sources. Please be sure to put your name on it.
  7. Staple the pages together and turn them in.

N.B. I suspect that you will find that even such authoritative maps disagree on basic facts, and that you may find this old cartographic aphorism useful:

"When the terrain and the map disagree, trust the terrain."