Each data frame in this map is exactly the same size and extent (click the map to see a detailed version [1.35 Mb]).
What: Maps that show a variety of information about the same place are often laid out as "small multiples". Each of the small multiples maps are the same size and show the same geographic extent, but the data on them vary.
Why: Cartographers often do this because we know that by varying only the data on the map and not the base information, the map reader focuses on the data changes and not on other things such as scale changes, projection variations and changes in extent. The constant layout makes it easier to compare and examine relative details of the data for specific locations within the area mapped.
How: Small multiples can be made by creating data frames that have the same size and extent and contain the same base map layers. Then you can add different thematic or operational data to each of the data frames. Here are the steps we used to set up the four data frames on this poster:
- The first thing you need to decide is the final page size. We typically hear requirements for posters at academic conferences and such expressed in terms of a "maximum size". To play it safe, you can set the page size in ArcMap to be the largest you are allowed to use.
- Create the base map to be used in all the data frames. We started with our base reference data and raw 911 calls data, then we symbolized those layers (very roughly, but using the general symbology for what we envisioned for the final map).
If you know that you will be using the same base information on all the maps, you might want to spend a little more time getting the symbology right so you don't have to edit it later. The thematic or operational data will have to be attended to separately for each map.
- Based on the number of data frames needed (for our map, we knew we needed four), you can guess at roughly how large to make the data frames so they fit on the page and there is still room between the frames and at the edges of the page. Do not forget to include the other page elements when doing this. Then you can resize your data frame to their optimal size which is usually as alrge as possible (unless the data displayed are not very complex and can be shown in a smaller space).
This is one case where interactively setting the data frame sizes and positions may produce inexact results. We have found that using the Size and Position tab for the data frame properties makes it more likely that we do this correctly the first time.
- Copy the data frame and paste the required number of copies into the layout. To do this:
- Select only the data frame you wish to copy (no other elements should be selected).
- Right-click on the selected data frame and choose copy.
- From the Edit menu choose Unselect All Elements.
- From the Edit menu choose Paste.
- By copying and pasting data frames rather than inserting new data frames and copying the base layers into each, you will save yourself the time of redundantly setting properties such as the coordinate system, reference scale, units, grids, annotation groups, etc.
- Set your data frame’s projected coordinate system prior to copying and pasting -- if you don't, you will have to start over from scratch because setting the projected coordinate system changes the shape of yoru study area, and thus the ultimate shape that your data frames should be.
- You can now roughly arranged them to get a first impression of how all the data will look on the page. You may find using the rulers, guides, or the layout snapping grid helpful in doing this. Then you can check how much space is left over for titles, legends, graphs, and model diagrams. In our case, we ended up making our data frames a little smaller to accommodate these additional page elements. If you also need to do this, simply delete the copies of the original data frame, resize the original, and make more copies.
In making small multiples, we have also added all the titles and pictures to allow ourselves to interactively experiment with overall composition layout.
- Next, you can fine tune the scale for the data frame and the position of each -- use the data frame properties to get more exact results. In making this map, we had to go back to the beginning several times before we got the layout right.
- We decided to print our map out at that point so we could see what was and wasn't working so well. We then made the final adjustments to our data frames sizes and locations.
Create a test print (a printed version of your map that is used to check your progress) for any map that is larger than your computer screen early in the process, particularly if there are multiple data frames, as each item that needs to be changed later will result in repetitive tasks and lost time.
If you would like to post a comment, please login.