This workshop will cover best practices for creating map figures for journals articles and academic texts. The exercises are designed to be run independently using QGIS 3.14. By the end of the workshop students will have gained the skills and information needed to create maps that meet the unique graphics requirements of typical journal publication while still being effective visual communication tools.

Prerequisites

In this workshop I'll assume you already have a basic understanding of:

• Common spatial data formats (vector and raster)

• Desktop GIS software, and QGIS specifically. Please see our Intro to QGIS workshop page first if you are new to GIS software or need a refresher.

Workshop setup

• Download and install QGIS - a free and open source desktop GIS for Mac, Windows, and Linux.

• Download the exercise data collection and extract it to your Desktop.

Background

Maps, graphs and other figures are the unsung heroes of academic publication. The content may be in the text, but maps and other illustrations are often where our eyes stop as we flip and scan through articles. They represent opportunities for quick bursts of densely packed visual communication. 

Academic publication presents a few unique challenges to creating effective maps and learning to work around those constraints requires a different approach than we might use for larger maps.

The most common design issues for journal publication are:

• small map sizes

• limited color (or grayscale only)

• low resolution

• data citation and licensing

What map are you making?

The first step in making any map is understanding the message you are trying to convey, along with identifying who you are talking to. Your map should be designed to address the specific topic and the audience who will see it. Here are a couple of real world examples:

The map on the left was done for full color book publication, accompanying the memoirs of Secretary John Kerry and depicts his travels by "swift boat" during the Vietnam war. The use of color and detail here draw attention to the boats path, but keeps enough context for readers likely unfamiliar with the regions geography.

The map on the right was a journal figure on the loss of habitat and range of China's Giant Pandas. Print limitations meant no color and a small design space. But readers were assumed to be familiar with the subject so the choice was made to leave background details off and focus instead on the the core provinces and panda habitat.

Journal art specifications

We still haven't made a map yet, but I promise we're getting there! There's one more set of details we need before we start actually creating a map, the journals art specifications. Every journal (book, and magazine) will have a set of specs that guide submission for images and illustrations. Because we're generally talking about print publication, the restrictions can be quite limiting in terms of what can actually be submitted. If you fail to meet the art guidelines for a given publisher you risk not having your maps included with your writing, or possibly worse, having the publisher modify your maps for you!

Let's look at one real-world example: Nature's Journals

I look for the following pieces of information:

• Maximum figure size: 89 mm (spans 1 column) or 183 mm (spans 2 columns) wide and maximum 247 mm high. This means our figures should be one of the two width dimensions and not a variation. We can have whatever height we need up to the maximum.

• Aspect ratio restrictions: none listed. That's fine because we have very specific dimensions.

• Color guidance or restrictions: Nature's Journal uses four-color reproduction (they use cyan, magenta, yellow, and black (CMYK) inks for printed material), but they charge for color figures. If they charge for color, try to make a grayscale map.

• Font guidance or restrictions: none listed for maps. Some journals will specify a particular font or that the font must be an open font. I suggest sticking with something fairly common unless you really need a special font.

• Format and quality: electronic format, suggesting .jpg files "at good enough quality to be assessed by referees". You'll eventually submit higher quality figures for publication but not for the review process. Some journals specify things like .eps files or .tiff at a certain dpi and may also expect a certain color space (like CMYK, RGB). Maps and other graphic figures are usually ok at 300 dpi given the small print sizes. Larger maps, full color maps, and maps with a lot of detail may benefit from being saved at 600 dpi. Note that if you can't supply an .eps file, a plain .svg is usually readable by Adobe Illustrator with minimal issues.

• Other limitations: Nature does not want figures to have separate panels within the same figure unless they are related to each other. This means we can only have one map per figure unless they are related.

Publishers vary in how much detail they give up front about these specifications and in may cases you will need to piece together specs for maps from different sections of the author instructions. Parts of the figure specs, photography, or graphs may apply. Be persistent, there is no point in starting a map without these details.

Page setup

After starting up the GIS and adding your initial data layers, the very next thing you should do is go into the print composer/layout view and set your output page dimensions. Refer to your art specifications for the exact sizes required. It's best to set the page size to the max width dimensions and adjust the length dimensions to suit the map layout. You might want to use a standard aspect ratio like 1:1  4:3 or 3:2 to maximize your maps compatibility with other display options. So if your max width is 90mm at 3:2, your max height would be 135mm (or about 3.5"x5.3").

Don't leave this step for the end as you'll end up building a map to the default page size of 8.5"x11" and be forced to shrink this to fit the journal specs later, or rebuild the map entirely.

Design

The goal in map design overall is to create something that is clear, legible, and communicates the intended message (and nothing else!).

Here are a few general concepts to keep in mind when making your map figures.

Visual Hierarchy 

Visual hierarchy is the separation of images into background and foreground elements (aka figure and ground). The order of our maps features in the visual hierarchy suggests their relative importance to the maps message. Ground elements are contextual while figure elements represent our data. Anything that stands out from the background will rise in the visual order. More important features should move to the front with less important contextual map elements moving to the back. Similar features should reside near each other in the visual hierarchy while dissimilar features should be separated. Maps with a flat visual hierarchy can be difficult to interpret.

Visual hierarchy can be affected by changing a number of different symbol variables like size, color, and contrast. Anything that helps separate features from their background will help establish them in the visual order.

Academic publications often limit us to black and white printing, but you can still create a deep visual hierarchy with no color by using different shades of gray to establish order.  Adjusting the amount of black in your map symbols will allow you to create a strong and varied hierarchy even when restricted to black and white printing. Anything between 10% and 90% will read as 'ground'. The greater the percent black difference the greater the visual contrast. Save full black for your data or 'figure'. Full white usually reads as empty or 'no data'.

Fonts

Font should be kept simple. Follow the art specifications but in the absence of specific recommendations, stick with well know common fonts. Avoid decorative fonts or using more than one or two fonts in a single map figure.

Use changes in the style of a single font family (bold   SIZE   s p a c i n g   italics  color) to create a variety of font styles that link them to specific feature types and reinforce the maps visual hierarchy.

Color

In most cases you'll be restricted to grayscale printing due to cost or other print limitations. When color is an option, you're best served by continuing to use grayscale for the background map elements and only adding color for your data. With a subdued map base, small amounts of saturated color will stand out clearly and create a dramatic effect in the visual hierarchy. Stick with natural colors over harsh bright colors and be mindful of natural mapping between colors and features (like reserving blue for water or cold).

Alignment and frames

Each of the various elements that can be added to a map in the layout or print composer can usually be placed anywhere on the page. Be careful to place these features where they won't obscure the main map or your data. Pay special attention to how each feature is spaced with relation to the map frame, page edge, or other features and try to use uniform spacing where possible to keep your map looking neat.

Avoid adding extra frames to these elements. Each new frame creates an obstacle to visual flow and can create distracting empty lines between elements (see the phenomena of 1+1=3)

Exports

Refer to the publishers art specifications for export guidance and follow their recommendations. Most publishers will ask for a raster export (a .jpg. .tif. or .png). You may occasionally be asked for a vector based export like .ai or .eps. If you don't have access to Adobe Illustrator to create vector exports, you can substitute an .svg or .pdf file as both can be opened and edited in Illustrator. 

If given the choice between vector and raster formats know that your vector map layout can be edited by the publisher but the raster format can not (not easily anyway). If you're a control freak like me this matters!

Download data

If you haven't already, download the data folder here and extract it to your desktop.

Our project data is organized into the subfolders listed below:

HI_base_data: contains Hawaii state outlines in two different scales and a buffer layer for adding a water effect.

contact_polygons: a series of polygon layers for the lava flow contact surfaces of three historic eruptions in the Kilauea East Rift area (1790, 1840, 1955), as well as the line layer for the main fissures.

KIL_2018_raster: a composite raster of the 2018 East Rift eruption combining the thermal IR band (band 10) from a series of Landsat 8 images captured between 5/16/2018 and 6/17/2018.

KIL_2018_poly: a single vector (polygon) feature representing the 2018 East Rift eruption.

Art specifications

We'll be following the sample art specifications for the journal Nature listed art the beginning of this page.

Set up the print layout

Referring back to our sample publisher specs from earlier we have these guidelines to follow in setting up our print layout:

• 183mm max width for a 2 column image (with a max height of 247mm).

• output should be a .jpg file.

• color is ok, export in a CMYK color profile.

Open a new layout:

1. Project Menu -> New Print Layout

2. In the window that pops up, give your new layout a name. I'll call mine "Nature Specs" so later I'll know this layout was for my Nature submission with this data. Click OK.

3. A new blank layout window should now be open.

Set the page size:

1. Right click anywhere on the white page in the middle of the window.

2. Select Page Properties from the menu.

3. On the panel on the right side of the screen, set the Size drop down to Custom, then set the Width to 183 mm and the Height to 183 mm. Note: there is a units drop down to the right of the Width and Height options.

4. Click the save button. This saves the whole project, not just the layout.

Now that the print layout is set up, we can close this window and come back to it after we've styled the data.

Style the data

With the page setup out of the way we can get back to styling the data for publication.

Let's open the Layer Styling Panel. This is a toolbar that can be docked on the side of the window and allows us to make changes to the layer styling with live updates (so we don't have to keep clicking to update).

1. Click the View menu at the top of the QGIS window

2. Choose Panels

3. Check Layer Styling - there should now be a panel on the right side of your screen.

4. Make sure the box next to Live update is checked. You can uncheck this if you don't want it to update choices automatically, for example, if you're working on a big file and it's slow to update as you work.

5. FInally, right click on one of the contact layers and Zoom to layer (adjust your scale and extent to match the image below).

Base layer

1. Select the coast_UTM5 layer from the table of contents.

2. In the Layer Styling panel, click on Simple Fill to reveal the advanced styling options for Fill and Stroke color.

3. Click on the Fill color swatch button to open the HSV/RGB sliders.

4. Set the H and S sliders to 0, and the V slider to 85% for a light gray fill.

5. Click the back arrow to return to the previous menu.

6. Select the Stroke color swatch button and set the H and S sliders to 0, and the V slider to 50% for a medium gray line.

7. Leave the Stroke width set to 0.26 mm.

Lava flow contacts

If the lava flow contact layers are turned off, turn them back on now. For each contact layer in turn, set the following fill and stroke colors:

1790_contacts:

• Fill color: H0  S0  V75% 

• Stroke color: set to fully transparent or 0% Opacity

1840_contacts:

• Fill color: H0  S0  V65% 

• Stroke color: set to fully transparent or 0% Opacity

1955_contacts:

• Fill color: H0  S0  V50% 

• Stroke color: set to fully transparent or 0% Opacity

Fissures

Because the fissure data are much smaller than the eruption areas, we can get away with full black here to help draw attention to these lines without overwhelming the rest of the map. 

1. Select the Kilauea_fissures layer from the table of contents.

2. In the Layer Styling panel, click on Simple Line to reveal the advanced styling options for Stroke color and width.

3. Select the Color swatch button and set the H S and V sliders to 0 for full black.

4. Set the Stroke width to 1.5 mm.

5. Stroke style should be Solid Line.

6. Change the Cap style to flat to help make spacing between fissures more noticable.

Lava flow composite image

The raster layer...

1. In the Layers panel, turn on the lava_composite_b10 raster layer.

2. In the Layer Styling panel change the symbology type from Singleband gray to Singleband pseudocolor.

3. From the color ramp drop down select All color ramps.

4. Select the yellow-orange-red-red color ramp (YlOrRd)

5. From the color ramp drop down select Invert Color Ramp.

Because rasters represent continuous data (unlike discrete vector data), our new layer covers up the other layers underneath it. Setting the layer to be partially transparent doesn't work as it would tint everything in the map orange. Luckily we can adjust the Min and Max symbology values to narrow the range of pixels we are symbolizing, making the rest of the raster disappear. We'll use a range of values that just covers the main lava flow, or regions of highest accumulation in the lava flow composite.

1. Set the Min value to 130000 and the Max value to 205092.

2. Under the Classify button, check the box for Clip out of range values.

3. Click Apply to see your changes.

Use the Move Item Content tool to interactively pan and zoom the data around inside the map area. You can play around with this until you get a fit that looks good. Or you can set a specific scale in the Item Properties menu. Just find the Main Properties item and in the Scale dialogue enter your desired map scale. I've set mine to 70000 (or 1:70,000).

Make adjustments until you're happy with how the map looks. Ideally we'll have the relevant map data centered filling our map layout.

Export Map

Most publishers require an image export of your final map. A .jpg is the most common file type but you may also be asked for a .tiff or a .png.

1. In the Print Layout window, select the Export as Image icon.

2. Select the export folder, give your map export a new name and click Save.

A new window will open where you can set the Image Export Options. Refer to your publishers specifications for things like DPI and color space. In our case we'll use 300 dpi. The output will be an RGB color file, your publisher can convert this to CMYK if needed or you can resave the file yourself in something like Photoshop or GIMP.