Lab: Generalization

For this project, you will make a set of clean, clutter-free maps in preparation for the next activity, which is adding symbols.  Instead of getting bogged down in the generalization tools of ArcGIS Pro to generalize the linework and polygons, we’ll instead focus on working with data sets that have already been generalized for specific scales.

Choose a country in Europe. For this first part of this lab pair, you will need to locate and label the following types of features:

  • Major cities
  • Major water bodies (rivers and/or lakes)

It’s part of the generalization process to determine what “major” means, but you should have a nice distribution of features, without the map looking full or cluttered – remember we are adding more data to this in the next assignment.  Look at some other maps of your country to help determine which cities and water bodies are considered significant.

Download data from Natural Earth (http://www.naturalearthdata.com/) or DIVA-GIS (http://www.diva-gis.org/gdata). You’ll need at least two different scales, possibly three, so Natural Earth is a good choice for your small and medium scale maps, and then you can decide which to use for the large scale map and other features.  Be careful about combining sources, as boundaries may not match.  Choose your scales so that detailed lines/borders are still detailed, but not chunky and blobby.

You will make this map at three different scales (this means you’ll make three maps, since you need different scales of data). One will be highly detailed, the other will be more generalized, and the third will be a locator map. The scale of the Natural Earth data for these maps will depend on the size of your country, and the amount of area covered in your locator map.  You can also generalize features by collapsing the geometry type.  As an example, the first map may use a polygon shapefile for cities, and the second may use point features. To get just the features you want, you can manually select them, or you can filter your data to only show features of a certain size, such as lakes larger than x square miles or cities over a certain population (Natural Earth uses ScaleRank, which is a population classification). You need to place your country in context, which means that you should include a little bit of neighboring countries.

Set up your page size at Legal (8 ½” x14”). You will need three data frames, one 8” x 10”, and the other two 3” x 3”. One of the small frames will be your locator map, which should contain all of Europe with your country highlighted. The other two maps should be of the same extent, zoomed in on your country of choice. Each map should have the representative fraction (Insert > Scale Text) noted somewhere subtle but readable. See map of Albania below for an example. Adding a text blurb is optional, but can help with awkward layouts – don’t forget to cite it.

Map of Albania
Sample layout

Tips for Success:

Check over your data in each scale for consistent generalization.  Make sure your borders match up – see that weird little sliver underneath Albania?  In this case, it’s actually part of Greece, but you need to check those kinds of things.

Use the RF as a guide to match the correct scale of Natural Earth data.  It might not match exactly, but if you’re using 1:100m data and your RF is 1: 40m, it’s going to be too generalized, and will look shapeless.

Dissolve rivers before selecting them.  Just like we did with Minnesota, only this time it will help with decisions also.  Also make sure to put the rivers underneath the lakes, in case you symbolize them slightly differently.

No size listed for the lakes?  Add a field and Calculate Geometry, then decide what your threshold will be.

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