Nuts and Bolts of Cartography with ArcGIS
An improved version of this tutorial is being maintained by the author at www.gismanual.com/mapping.
The goal of this tutorial is to provide hands-on experience with the techniques of producing context maps in ArcGIS. Transforming data into graphics that communicate key ideas about how our area of interest consists in a network of named physical and cultural features connected by corridors of various types and interrupted by edges, barriers and invisible boundaries. We assume an understanding of our first tutorial, Collecting GIS Data and Metadata in ArcMap.
Download the Tutorial Dataset
- ArcMap 101: A quick tour of the ways GIS is used to organize spatially referenced data.
- Elements of Cartographic Style Provides a deeper explanation of the goals of mapping and the elements of various types of maps.
- For an example of a good set of topographic maps, see A PDF of some maps created using our sample dataset.
- Fundamentals of Map Projections
- How Maps Convey Geographic Information
Objectives of this Tutorial
- Begin your map recalling basic data handling and transformation concepts
- Choose an Appropriate Projection for your map
- Develop simple statements about a few critical aspects of Local and Regional Context
- Choose and portray data to create a graphical hierarchy as described in Elements of Cartographic Style.
- Create a map layout & scalebar and captions
- Add labels and graphics to map. Experiment with ArcGIS annotation
- Export a layout as PDF, JPG
- Use your contextual framework as a template for a another thematic map exploring some data.
- Compile multiple pdfs as a single document
Begin with a Purpose
Having a goal makes any endeavor interesting. All of the maps we make should have a specific, stated communication goal. It goes without saying that without this, a map is pointless and cannot be evaluated. In the case of this tutorial, we are carrying forward the goal that framed our first tutorial> We want to understand how the proposed extension of the MBTA Green Line will affect the city of Somerville, Massachusetts. This particular mapping project will examione the context of the neighborhood Union Square as it is today, as the setting for two of the proposed stations on the greenline extension.
Understand Map Projections
Our assignment is to make maps of regional and local context. On maps of this scale, we should assume that the assumptions of topographic interpretation will apply, namely:
- Distances measured on the map will have a consistent scale no matter what part of the map they is measured.
- the cartinal directions, North, South East and West will meet at right angles. (typically North is at the top of the map, but not necessarily.
You may take these assumptions for granted, as would most map users, however, we will see that assuring that these assumptions hold true requires acive attention to the choice of a map projection.
Start your Map by Opening a Layer
We will begin our map by going to our data collection and adding some information that we captured from ESRI streetmap according to the method described in Beginning a GIS Database. Here we will observe that arcmap sets the map projection of our Data Frame to adopt the native projection of the datasets that we open. To make this clear, we will begin by opening some world-wide reference layers that will help us choose an apropriate projection for our map.
- Start a new map document in ArcMap
- Inspect the Dataframe Properties (double click the thing called Layers at the top of the table of contents to check the geometric transformation being applied to the map.
- From the tutorial dataset, add the world_countries.shp shape file from the world_reference folder of our sample dataset.
- Check the coordinate system properties of the world_countries.shp layer -- listed among teh Source Proerties for the layer. See how the dataframe adopts the coordinate system of the first dataset that you open.
- Check the projection properties of the data frame. See how the data frame has adopted the coordinate system of the first layer we have opened.
- Add the layers from the streetmap folder within our greenline_ext folder. YOu will find this in /sources/esri_streetmap/roads.lyr, and check the spatial reference property of these datasets.
- add the USGS_Hydro, MBTA, towns and openspace Layers from the greenline_ext/sources/massGIS folder.
- Take a look at the native coordinate system of the MassGIS layers. Note that the ArcMap project is transforming the geometry of the massGIS data to overlay with the other layers, even though the data have their coordintaes defined according to two different systems!
This sequense of steps illustrates a couple of important things. First, that the projection of our map is determined by the order in which we add datasets to tne map. Second, that subsequent layers that have their coordinate systems defined can be transformed on-the-fly to overlay coherently with the other layers in the map, regardless coordinate systems inherent in the other layers.
Investigate the Geometric Properties of your Map
If you thought that our discussion of map projections in class was merely academic, the following series of steps should drive home the fact that a failure to understand the projection of a map can lead to a very major blunder. Understanding this, you will agree that a map intended to be used for interpreting shapes and directions should declare what projection has been used to transform the data.
- Measuring Distances and Areas
Create and Measure a "Circle"
- Look for the Draw Toolbar at teh bottom of your Arcmap window. If you don;t find it, right-click on an empty part of the toolbar ribbon at the top of the window, and check the box next to the word Draw
- On the draw toolbar there is a little pulldown that has a square in it. Pull this down to choose the Circle Tool
- Zoom in to a small neighborhood on your map.
- Choose a street intersection for the center of your circle, and pull a circle out from this that covers several blocks in your street map.
- Double-click this graphic and adjust the properties so that it has no fill and a thicker red outline.
- Now choose the Measure Tool from the standard ArcMap tool palette.
- The default units for the measure tool may be decimal degrees.
- Inspect the length of the radius and the are of your circle in decimal degrees. What does this mean? IN fact, measuring the length or an area of a shape in terms of degrees is meaningless. Degrees alone are not useful measures of length or area.
- Click the Sigma button on the Measure tool palette to change the length and are units to units that are comfortable for you. Now measure the radius of the circle, first in the East-West dierection, then in the North-South direction.
- Hmmm. Question: When is a circle not a circle? Answer: when it appears on a map that is using an inappropriate projection!
Choose an Appropriate Transformation for your Map
From our Map Projections you are aware that you must always be aware of how ArcMap is transforming the geometry of your data to display on your map. If you let ArcMap choose the method for transforming the geometry in your data, you will very likely be portraying the directions sizes, shapes, and relationships of the entities in your map in a substantially distorted way. This will make your north arrow and your scalebar more or less useless. Therefore, you should understand how to choose an appropriate projection for your map. And if you want to bolster your credibility, put a note under your scalebar to reflect the projection case that you have chosen.
- Inspect the Dataframe Properties (double click the thing called Layers at the top of the table of contents) to check the geometric transformation being applied to the map.
- Use the Drawing Tools to draw a circle on the map centered on some detail that you can find again.
- Open the shape files for the US State Plane Zones and the Universal Transverse Mercator zones in your map. These are in the gis_tutorial/world/ folder. Normally you can find these in Program Files(x86)/ArcMap/Referencing_systems folder.
- Use the Information Tool to find the appropriate State Plane Zone for your area of interest. For the Boston area, the most common projection would be Massachusetts State Plan, Mainland Zone, projected on the North American Datum of 1983.
- Set the transformation for your data frame appropriately. Note that the Compilation.mxd that for thus exercise is set up with the correct projection already.
Think About Critical Elements of Site Context
Our mapping project begins with a descriptive intention that we might summarize in a short paragraph, as follows:
We are interested in Union Square, a neighborhood in the City of Somerville. Union Square is very close to the cities of Cambridge and Boston. Currently Union Square is not very accessible via light rail. But this is going to change in the future because of a planned extension of the MBTA Green Line.
The exercise of describing the place helps to define the elements that we want the nap to emphasize and to decide on an extent for the map. We need to show the proximity to Boston and Cambridge and the distance from the existing nearby light rail stations.
Once we have used the Map Zoom and Pan tools from the ArcMap toolbar to get an extent that looks reasonable, we can use Bookmarks > Create to save the extent so that we can easily return to it.
Building a Background
Now that we have chosen an extent for our map, we will begin building the graphical hierarchy, starting with a nice, easy-on-the-eyes background. The background layer of the graphical hierarchy will convey the physical setting of our area of interest in a subliminal way -- that is without demanding any attention from our audience. These background layers will help the user orient herself with regard to the well-known framework of the city, and it may also convey useful information about context, like open space, and the pattern of circulation. Adding these background layers will acquaint us with some of the basic procedures of adding and changing the display characteristics of layers.
- Lets add the shaded relief layer from the ESRI Web Map Service: File > Add Data from ArcGIS On-Line Enter the term Shaded into the search box, and pick a layer to click Add
- Drag the layers around to adjust their display order.
- Now adjust the symbols for your streets so that they do not command so much attention.
- The automatic labeling for streets creates a lot of information that is distracting. Lets turn them off.
- Finally, put the shaded relief layer on top and adjust its transparency to %50.
Our map now has a good foundation!
Creating the Reference FrameworkThe Background, or bottom of our graphical hierarchy takes care of the ambient context. Another thing that the map should do is answer specific questions that the user may have and to put labels on things that are likely to be part of the discussion. These are aspects of the map that we want the reader to notice. So we will use darker colors and may employ a light background behind the linework and text to pull this reference information above the background.
Our descriptive paragraph establishes that the relationship between Union Square with the cities of Boston, Cambridge and Somerville. Since these elements are essential to our discussion we should name them.
- Add some layers that will help you to highlight the key elements of your description
- Since a critical aspect of Union Square is its relationship with Boston and Cambridge and Somerville, it will be useful to add the Town Boundaries layer from the massgis folder.
- Since the towns are something we want to lift a little off of the background we will give the boundaries a thick dashed boundary. This is accomplished by editing the Symbology properties for the polygons. After turning the fill color to no-fill, we can adjust the boundary line style by clicking Edit Symbol in the symbology panel, then clicking Outline.
- We want a dashed outline with a background so you can pick the predefined line-symbol: Boundary State from the panel of samples.
- Then to get fancy we will make the background line pink by changing the color.
- if you want to see how to make your own complex line symbols, click Properties again to reveal all of the different ways to make lines with multi-layered symbols.
- We don't want the town boundaries to completely clobber the roads underneath, so we can go back to the layer properties, and under Display we can set the layer to be 40 percent transparent.
Working with Auto-Generated Labels
We will demonstrate some basics of labels by labeling the towns. We want the town labels to be at the same level in the graphical hierarchy as the town boundaries. We can also make it easier for our readers to associate the town names with the town boundaries by lifting them off the background with a similar pink outline.
- Take a look at the attribute table for Towns. Note that the Name attribute holds the name for each town.
- Double-click on the layer and look at the Label properties.
- Select Name as the label field, and adjust the font size and weight.
- Now for the halo, click the Symbol button then click the Properties button, then click the Mask tab. You can now set the color and the width of the halo.
- Sorry that is so many clicks. You could probably figure out a better interface for this and send it as a suggestion to ESRI.
- Finally you can click OK until you are back at the map and then right click the Towns layer and choose Label Features.
Create a Layout
To make a nice map for presentation, we will need to be able to model a sheet of paper that will give us room to include our paragraphs of text, scale bars, projection information and source notes in the margin of the map and all of the other things discussed on the page. This layout can also contain text and graphics that are fixed to the map.
Go Into Layout Mode and Add a Scalebar and other Marginalia
- Choose View-> Layout to go into layout View.
- Adjust the File->Page and Print Setup to make your page landscape format
- Use your Black arrow, (aka Pick tool) to adjust the map frame to fit on the page.
- Note the layout toolbar. Play with these tools to understand how to navigate around the page.
- Note that the regular toolbar still works to navigate in the map window.
- Add a title that reflects the subject of your map. Perhaps, "Site Name, Topographic Detail". Where site name is the name of your site.
- Add a scalebar to the map and adjust its properties (see the reference above)
- Once you have the scalebar the way you like it, double click to go backl to the properties and pull down the option that says When Resizing... -> Change Width this will eliminate the annoying tendency for ArcMap to change your scale bar terminal units to something funky if you make slight adjustments to the map. For the sake of making things easy for your users, your scalebar should end on some nice easy unit. Now you can explore the various features of the Draw Toolbar to add blocks of text for your map explanation and source citations and for identifying the projection case that you have chosen.
Adding Graphics and Text to the Map
The drawing toolbar can be used to add graphics to the map. This is where we will add a few things that will be on the highest -- Foreground -- level of our graphical hierarchy -- such as the red box and label that identifies our area of interest. We will also add labels for the major roads and the landmarks, etc. -- especially all of those things that we mention in our paragraph. The most important thing to remember if you are making graphics that you want to move and scale with the map, you need to double-click in the map frame so that it grows a hatch around the edge that indicates that graphics that you add are added in Map Space.
Adding Text in the Margin of the Map
- Look for the Draw Toolbar at the bottom of the ArcMap window. If it is not there, go to Customize > Toolbars > Draw to add it.
- Use the Text tool to add a title.
- Use the Polygon Text tool to add a caption. Note that this works best if you set your text options to justify on the left.
Adding Foreground Text and Graphics to the Map
Now we are ready to add the icing to the cake. We need to call attention to the primary subject matter of our argument. Where is Union Square? We will add a red box and a label that identifies our area of focus. We want this label and the box to move if we shift or zoom in on the map. To accomplish this we need to change the focus of the drawing tools to Map Space.
- Double click the data frame (map) in the layout window so that the edge of the map frame becomes hatched, This means that you can add graphics that will move with the map.
- Use the Draw tools to make a box that identifies your specific area of interest, and you can double click it to change its properties (to make it a red outline with now fill, for example.
- Optional: If you want to pull your red box off the map you can change its line symbol to incorporate a wider white line behind the thinner red line. To do this, double-click the red box to bring up its properties. Then choose Edit Symbol Then choose Change Symbol. Here you can use the Layers tool to put a wide white line behind the ref outline which will make the s red boundary appear lift off of the background.
- Find the Add Text Tools by clicking and holding the A on the Draw Toolbar. You can then add a label identifying this box as Union Square.
- Double-click your label to edit its properties. Here is where you can make it red. If you choose Change Symbol then Edit Symbol, under the Mask tab, you can change the Halo settings to put a white halo around your text to make it raise off the map.
- When labeling things like streets, you may want to use a halo as discussed above, but these street names should not be emphasized as much as your area of interest box.
- Before making a lot of labels that are the same, It can be useful to select Default Symbol Properties from the Draw Toolbar menu to set up the kinds of line, text and point symbols that you plan to use. This way you don't have to set the style for each one. Also note that labels can be rotated or even laid along a curvy line.
A legend? In these general context maps it is best to stick with portrayals that follow basic conventions of symbology. Water should be blue, protected openspace should be green, roads should be displayed in a graphical hierarchy. IN this case there is no need for a legend. But since you will use this same framework for thematic maps later, you should leave room for a legend in your layout.
Saving the Map Document
Now we are almost done. We will save our map document -- since this has been a lot of work and you can rest assured that we will want to revise it later. Make sure to save the map document in the docs folder of the data collection. Use the Source view of the table of contents to make sure that all of the data referenced are underneath the same folder that also contains the document.
- Set your Table of Contents to Source mode and double check that all of your data is in the same folder tree with the data that it references.
- Check the File->Document Properties->Data Source options and make sure that you are using relative path names as discussed in the tutorial beginning a GIS Database
- Create a folder for yourself within the GIS Tutorial folder. Within this folder make a folder named map_docs. Save your map document to your map_docs folder. Give it a name that ends with _1 so that you can save incremental versions.
Exporting your Map to JPEG or PDF
ArcMap documents are good for exploring data and authoring graphics but not great for sharing graphics. TO do this we will want to be able to save our maps to jpeg files or pdf or oter formats that can be opened in Acrobat Reader or desktop publishing applications like illustrator. In this, you should be able to adjust the various options so that you can control your resolutions and avoid common problems with fonts.
- Look at the File>Export Map options for exporting your map as a jpeg. Notice that you can adjust the DPI.
- Export your map as a PDF. Check the export options to see that you can embed your fonts. This is a very important thing to do, otherwise your special map fonts may be converted to jibberish your maps are viewed on a computer without ArcMap installed.
- Open your new map in Acrobat Pro. Note that you can use Document>Insert Pages to build a pdf document with multiple pages. You can use Microsoft word to add title pages, and bibliographies, etc.