GIS Blog

Atlas Would Be Jealous

In this post we look at creating a map series of similarly formatted maps.

Here a GIS Central we recently started some work looking at the carrying capacity of cruise ships in Fiordland.  There was some field work involved so to carry out some of the work, the good people at Pacific Eco-Logic needed some maps, specifically, “a grid at 1: 100,000 scale on the aerial/satellite imagery of the fiords of Fiordland based on printing out A3 sheets of paper for fieldwork. I would need the fiords and their catchments included”.  Certainly sounds like something GIS should be able to help out with.

My first thought was that this would end up looking like some kind of an atlas of maps, with all at the same scale and accompanying information but each focused on a different area.  While this may sound like a daunting task at the outset, it’s something that ArcGIS is set up to do relatively easily through the idea of map series.  It couldn’t be much simpler.

To get started, I need a layer of polygons that cover the area of interest without overlapping that defines the extent of each map page.  I could create one myself, using something like Create Fishnet, but immediately I thought of an alternative that might make more sense: the 1:50,000 scale Topo50 map series.  These maps cover the NZ landmass with 448 sheets, each 24 km east-west and 35 km north-south.  Here’s what the South Island coverage looks like:

Each sheet is assigned a code that places it in the large scheme, with two letters per row and two numbers per column, a bit like the grid used in Battleship (Ed. the game, not the movie, sheesh)

I grabbed the sheets covering Fiordland and then got some feedback on which ones would need and ended up with this as my index layer:

Here’s the layer’s table so you can see what it’s got:

“DESC_” holds the text name of each sheet while “PRIME” is the Battleship-like identifier.  “row” and “col” just split those up for selection purposes (e.g. to select all the sheets in the same column).

Great – this gives me my map extents.  For the satellite imagery, I simply changed the basemap to World Imagery (Firefly):

Next up is to set up the map series parameters.  I first need to create a layout and build the basic labelling and symbology that will appear on every page:

Some of the key decisions on this one were around sheet border colours and label placement.  Given the overall darker tones to the satellite image, a dark outline colour could easily get lost, so I chose a softer, light-gray and matched this on the labels.

Most atlases put labels on the sides where another sheet abuts the current one to make it easier to move between them – I can do this by choosing the boundary placement in the Label Class window.  To get here, right-click on a layer you want to label and go to Labeling Properties…  Here’s where you can make all those choices around font size, type and colour and hiding under Position are the placement options.  Boundary placement works well in this context by placing the sheet name for the current and surrounding sheets:

Font size controls how much emphasis they get.  I’ve also placed my scale bar and have a placeholder for a legend (more on that later on).  On the Layout tab one of my many options is Map Series:

Spatial is the option we want here.  It’s a pretty simple setup:

A key choice here is the “Layer” – this is set to my layer of Fiordland Topo50 map sheets.  In that layer, the “PRIME” attribute holds the code of each sheet so I’m using that for the Name Field.  Sort Fields are used to set out the order that each map in the series is put into.  Options include things like rotating the map frames, setting extents, and controlling output page numbers.  When done, it’s all put together with no muss and little fuss:

From here I can move between each sheet by selecting one in the Contents.  Once set up I can always go back and tweak this by right-clicking the Layout name, going to Properties and choosing Map Series.

Before I can say I’m done, I exported a few of these as A3 PDFs and ran them by the field workers.  For the first round, they seemed pretty happy overall but had this comment: “What would be really useful would be to have the bathymetry for the marine environment shown”.  No problem!

I just happen to have a layer of offshore 50 m bathymetry from NIWA (you can find it at J:\Data\Bathymetry).  After a bit of back and forth on symbology, we settled on this:

(Oh dear…really should have included units in my legend…maps are never really done.)   This does show one of the trickier aspects of map series – placing an element in the same place on every page can cause conflicts with covering features on certain map.  Short of making each one custom, one must learn to live with that I’m afraid.

In any event, we’re just about done here – next job is to export the sheets as PDFs and send them off.  With the map series Layout active, look for the Layout Export button, , on the Share tab.    With the Type set to PDF, the Map Series tab becomes visible:

You’ve got choices on what to export (including only selected features in the index layer).  I suspect these are less useful as a single PDF file in case they just want to print out specific ones.  Clicking on the Files down arrow, I do have some other options:

With the second option, I can print each one out separately with the page name or number (as set in the Options earlier) as the suffix.  This seems pretty handy to me so option two it is.  Once exported, they all went to a folder on OneDrive which I could then share.

Note that I threw in a sheet index that hopefully made it a bit easier to make sense of where everything is:

With that they were off to do their field work.  I checked in a few weeks later – to which they replied, “We completed the field trip with mostly very good weather and your images were very useful”, to which I swooned.

So, where have we gotten to in this post?  Vicariously, Fiordland, but more importantly we’ve seen just how easy it is to make your own atlas.  All up, this probably took me a wee bit less than an hour to spin up, which is pretty good value for money.  Atlas was said to have carried the weight of the celestial world on his shoulders (and by the by, it was Gerardus Mercator, he of the Mercator projection, who coined the name Atlas for a book of maps), but Pro has certainly taken the weight of my shoulders by making this so easy.

C

• 25/03/2021


Previous Post

Next Post

Leave a Reply

Your email address will not be published / Required fields are marked *