|Broadcasting Your Spatial Data to the Masses: It's All about SCALE|
|There are some truly great cartographic masterpieces out there hidden on 'desktops,' and as a result, often only available to the few. An increasing number of these assets, which are used to illustrate sophisticated and often detailed information, are now being broadcast to wider audiences through publishing software such as MapInfo® Stratus™ or Web-Tiling Services such as those available through Spectrum Spatial.|
To make things easy to remember this article will introduce the mnemonic (or acronym) 'SCALE,'. Some of the important considerations are listed below.
Suitability: Which map features are relevant and which should be removed? Most humans don't gravitate towards clutter and lack of clarity and this also applies to maps. Usually the more clean and concise, the faster and easier it is to interpret and fully understand. If you're publishing your spatial data and it's captured at a small scale (showing large areas of land), keep the background mapping and features displayed at an appropriate scale too. Also remember the transition from vector, where an individual can click on objects and return associated attributes, isn't often a luxury available for server based or web mapping Ensure those objects can be understood by their visual appearance alone.
Tip: Basemap Clutter can confuse your message. Your focus could be on an arterial route into a city, for example, the main Highway 95 into Augusta, ME, United States. Figure 1 (below) illustrates how the Highway can be difficult to distinguish at a small scale with too many other map features displayed. Figure 2, in contrast, draws the user's eye and provides basic context instead of displaying many towns and additional roads. Of course, you can bring in the additional towns and roads when the user zooms in.
In figure 1 the detail has obscured the highway. Map produced with MapInfo StreetPro USA ©TomTom BV
Complexity: Complex vector geometries can impact on rendering speeds, for example, when using a service to create raster tiles. Think about using thinning/snapping technology to remove detail which is hard to distinguish at small scale zooms or is for display purposes only; take a look under MapInfo Professional's Objects...Snap/Thin menu which amongst other functions removes nodes from objects while retaining their shape. Tip: Experiment with these functions to understand how they work and what the results mean to your project. Some initial up-front research can pay big dividends when many levels of tiles are being generated.
Figure 3: Working with Objects in MapInfo Professional
Ask: For every decision, ask yourself, "how does this help clearly and effectively broadcast my map, message or theme ?" For example, it may not be appropriate to display Business Points of Interest on your United Kingdom Parks and Recreation areas Base Map.
Labels: You may experience issues when putting your vector data through a tiling service, such as labels being cut off at the edge of tiles or not being displayed at the correct zoom. Take note of padding options such as those available in Spectrum Spatial which reduces issues concerning labels displayed at tile edges and remember to review label zoom settings and adjust accordingly.
Tip: Keep in mind that the zoom settings in MapInfo Professional refer to the width of the map window on your screen. When a tile service converts your vector objects into raster tiles it will take your screen (Level 1) and divide it into 4 (Level 2) then this into 16 (Level 3) and so on up until the maximum number of levels chosen. Be wary that the generated tiles my not fit previous labelling schemes.
Figure 4: Generating tiles from MapInfo StreetPro UK. Data is ©TomTom BV
Ensure: you check your progress regularly and back-up often. How does your map look? How long does the tile generation service take to run a sample area? Waiting until the very end of the process can mean going back to the drawing board. A project can look great on plan, but there is no better way of ensuring a good result than regular reviews.
Tip: Saving multiple examples at different stages of your project allows you to easily return to a previous version if you change your mind. It's also useful for compare and contrast selection when choosing the most impactful or effective map.
Of course there's a lot more detail involved with the process of publishing your maps and data, however following the SCALE principles above, you'll be off to a good start, effectively broadcasting your information to the masses.
Article by Craig Pinhorne-Smy, Global Data Evangelist
When not writing articles for "The MapInfo Professional" monthly journal, Craig enjoys enabling MapInfo Professional users on the data portfolios from Pitney Bowes Software and our 3rd Party data partners. Craig is also a running enthusiast, a brown belt Judo competitor and enjoys just about any form of exercise to keep away the cobwebs.