GEOG 585
Open Web Mapping

Lesson 2 assignment: Analyze two web maps


For this week's assignment, find two web maps "in the wild" and create a post on the "Lesson 2 assignment forum" on Canvas that describes the following for each map:

  • The web address (URL) of the map and who created it.
  • The basemap, thematic layers, and interactive elements in the map.
  • The servers and display techniques used for each layer (tiles, image drawn by the server on the fly, browser-drawn vector graphics, etc.). Use your web browser's developer tools/plugins to figure this out. For example, using the Network tab of the developer tools while you pan around the map, you might determine that your web map is pulling in a tiled basemap from This is enough for the assignment; you don't have to go into further technical details about how the tiles were made or their file structure.
  • The software and programming framework used to build the web map (if you can determine this) and whether it is proprietary or FOSS.
  • Suggestions on how the map administrator could make this map more useful or faster performing.

Please make an effort to find these maps on your own. In other words, do not choose any of the web maps previously referenced in this lesson, nor should you browse through other students' posts in order to find maps to analyze. Except for the first point (URL), please use short paragraphs to address the different points in your description similar to what you saw in this lesson, not just bullet point enumerations.

If you are having difficulties analyzing your web map, please refer back to the section "Elements of a web map" and the examples and techniques using your browser's developer tool described there. If you check out the requests in the Network log, requests for images drawn by a server will be relatively easy to identify because the individual images sent back to the browser as a response will be image files in one of the typical image formats (.png, .jpg, etc.). You will be able to see images under 'Preview' of the Network tab. Looking at the preview images will allow you to identify which layers are included, e.g. is it just the basemap, just one thematic layer, or maybe basemap and thematic layer combined. Then the last question is whether these images are tiles, so are multiple images requested and then put together to cover the entire area of the map you are seeing, or is it always just a single image covering the entire map area (something that, for instance, you can experience with a WMS service where the browser tells the server the extent of the area covered by the map, the server then renders an image for that area and sends it back to the browser).

With requests for vector data that that is then rendered by the browser, things are more difficult. The vector data sent by the browser can come in a variety of formats (.json and .pbf are common ones) and is often in a binary format or in some other way compressed, in which case there is no direct way to check out what exactly the files contain. So if you come to the conclusion that some of the data for your map is not coming in as images, that's goood enough for this assignment. If you are able to identify some candidate requests in the network, you should mention that and the server these are going to, but in some cases even that can be difficult, e.g. when the vector data is just stored in a local file on the same web server that is hosting the page with the map.