Exploiting your Basemap
Design a custom vector basemap to suit a map or a story
Esri provides an increasingly varied set of vector basemaps of the world for you to use.
They can be considered as a starting point though. One of their features is your ability to customize both their look and content. It gives you the opportunity to create some distinctively different basemap looks of your own, to tailor the minute details of the basemap to your story, and hopefully to have some fun! ...
In this piece I'm not planning to talk about the practical aspects of working with our basemaps. For that you can go here . Rather I'm going to look at some of the design decisions you may need to make.
A few years ago I put together a Story Map on some of my favorite places to visit in Great Britain. To support it I created a custom vector basemap, and I’m going to use it here to demonstrate how to be constructive about the changes that you make.
Where to Start?
Most likely this means finding an existing basemap that is closest to meeting your needs. You are not necessarily looking for the most colorful, or the coolest design (nothing wrong in choosing based on that if it suits your story!). You want a map that is going to support, but not overshadow, your information.
I wanted a basemap that was dark, so that it contrasted nicely with the very strong icons I was planning, but I didn't need a lot of map detail. The logical starting point was the Dark Gray Canvas Basemap:
Detail was not needed, because I planned to switch to imagery at larger scales when the geographical context had been established:
I wanted to build these in one web map so that I could zoom between the two. The question was how to handle the transition smoothly and unobtrusively. At this point I decided I needed to customize the basemap.
Making Changes
If you want, and if you have the time, you can make sweeping changes to the basemap (You may want to tie it into a brand, or you may just want to personalize it to some extent). Be warned though that the more dramatic the changes you make, the more work needs to be done to balance all of the map information.
In my case I'm trying to solve a specific problem - create a smooth blend into imagery. My changes can be subtle, and that will minimize the amount of extra work.
However, imagery is notoriously difficult to match to, because it runs a whole gamut of earthtones.
Fortunately for me, the UK is largely green, so I can get what I want by adding a green caste to the land. I want to keep the 'Dark Canvas' look, so I don't want to do anything too dramatic:
For the scale at which I make the transition, the water in imagery tends to be a deep and dark blue - ideal for my needs:
Now the work starts! I've established the overall palette for the map, but all of the other features need to be assessed and, if necessary, changed. And not just at this scale! I need to zoom in and look at the details at all scales. Because my changes are subtle, I've minimized the amount of damage done to the map symbolization, but it should all be examined. Here is the completed map:
It consists of the vector basemap, and Esri imagery (at this scale the imagery is not visible).
All other symbolization, at all scales, was examined. Some of it was adjusted to work with the new backgrounds, and to support my story.
Progressive opacity settings in the VTSE
Using the Vector Tile Style Editor (VTSE), I adjusted the opacity settings for the land polygon so that the background (imagery) was slowly revealed.
Progressive opacity settings in the VTSE
Finally, I switched the map off completely using the 'Scale Range' bar at the top.
Zoom in and out on the map to see how this works.
Promoting Basemap Content
Most of our basemaps are designed to work in a narrow tonal range, so that they remain in the background, and your subject information is promoted. However, there is no reason why some of the basemap content can't become part of the map subject.
For my story, I made a copy of the vector tile basemap, and elevated some features:
I've picked out the Motorway / Highway categories of road in a brighter blue, to give a sense of where my locations sit in relation to the major road network.
The second change is to third-order boundaries - counties in the UK (counties are referenced in the text). I've picked these out in a yellow, and enlarged the county names to match their prominence.
I think this works well for Great Britain... and for my map ...
It's not so good in other parts of the world, and this should be part of your consideration.
In this case, in France, the 3rd-order boundaries (e.g., 'Seine-et-Marne') are much stronger than the 2nd-order (e.g., 'Ile-de-France').
If you want the basemap to be used by a general audience keep a separate 'generic' version it. I can make the changes to a copy for my use within the UK without compromising other uses.
Summing Up
- I created a custom version of an existing vector basemap to serve specific functions within my map ...
- I was careful to examine all map symbols at all scales to make sure that they were still working together.
- That included scales and areas outside of my particular requirements, so that another user could use this as a starting point for their map (In other words I created a complete multi-scale basemap).
- In a separate copy I used color and size adjustments to promote some symbols, so that they became part of the subject of my map.
Building a custom basemap can be a fun process! But know in advance what you are letting yourself in for. There is a 'knock on' effect caused by changing even one map symbol, and this can be magnified in a multi-scale service.
Don't feel you have to over-engineer your map, but be prepared to examine all aspects before using it, and certainly before releasing it to a larger public.
