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Why Georeference an Orienteering Map?

georeferencing image

What is georeferencing?

In simple terms for orienteering, georeferencing is aligning a map with the national map grid. On a georeferenced orienteering map, any point can be related to its location on the national grid and thus on the ground. The national projection is Map Grid of  Australia 94 (MGA94). The related datum is the Geodetic Datum of Australia 94 (GDA94) and is expressed in latitude and longitude.  GDA94 is consistent within 1 metre to the World Geodetic System 1984 which users of a GPS device may recognise as WGS84.GPS image

Why georeference O maps?

Having just mentioned GPS, the first response is that a georeferenced map enables import of GPS data or a GPX file with automatic correct placement on the map. On a non-georeferenced map you would be faced with moving via mouse, the GPS track and waypoints to the correct position – often a very tricky task. Data from a TruPulse laser rangefinder  can also be captured in the field (Professional edition) and appear instantly in the correct location on the map.

ortho photoA second response is that with a georeferenced map, ortho aerial photos such as provided by NearMap are automatically aligned with your map. Similarly for georeferenced data and georeferenced PDFs.  A huge time saving and likely a far more accurate result when transcribing detail from the photo.

A correctly georeferenced map minimises distortions in the map which can trouble elite orienteers. One map I have run on a number of times troubled even me. I had the opportunity to georeference it recently and found a section of it was so badly distorted that it also affected placement of features beyond that area.

When and how to georeferenceShape & DXF image

Ideally when the map is first created. Sources of data to create a georeferenced base map include Shape (Professional edition) and DXF files from state mapping and local government. Shape files generally offer the most useable data and are easiest to use. Open Street Map data may be useful for some types of map (Professional edition but see free service below).

Georeferencing existing maps is reasonably straightforward if you have access to map data that is already georeferenced. My preference is to georeference against GIS data. This is now free and easy to download in some states including Victoria. I usually use the roads data set from the Transport shape file as road junctions, as opposed to tracks, are fairly accurately positioned.

A scan of a topo map is also reasonable straightforward although a georeferenced digital data map is even easier.

Be prepared for distortions to show up especially if the map was not created by a professional mapper. OCAD will fairly successfully correct slight distortions. But if they are considerable and/or a section of the map is grossly distorted, then the Rubber Sheeting function in OCAD Standard and Professional is likely the only answer. OCAD website has videos on georeferencing and rubber sheeting.

Georeferencing service

While georeferencing is within the capabilities of most orienteering mappers, updating a library of maps may not be best use of your time. I offer a paid service to do the drudgery for you. See the Cartographic Services page for more information.

OSM import free serviceOpen street Map logo

Want to use OSM data but don’t have OCAD Professional edition? Read more...

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Swiss Maps Swap 5 colours for 4

Stochastic screening

Switzerland’s WOC’12 maps printed CMYK

Through research and utilisation of the latest processes in four colour (CMYK) printing, Switzerland was able to produce maps that satisfied the demands of our sport’s prestige events — the World Orienteering Championships.

Part of the story was OCAD’s new Layout Layer which made it easy to incorporate sponsor logos, printer’s crop marks and other useful map artwork.

Switzerland’s O magazine earlier this year published an article by Thomas Gloor, CEO of OCAD, on the topic. You can read the English translation (PDF 2pp)

Is this important to Australia and NZ?


Firstly, the cost of top class CMYK offset printing is generally lower than that of PMS (Pantone) offset printing for the relatively small quantities required by our sport.

Secondly, CMYK printing enables the easy incorporation of raster (JPG, TIFF, PNG, GIF) images such as sponsors’ and clubs’ logos plus photos.

So are we lagging?

Maybe not a lot.

With one exception (see below) I have always presumed WRE (World Ranking Events) and above in Australia are PMS printed. A quick look at the relevant page on the Orienteering Australia website supports my perception.

However, I am aware that at a lower level,  Bendigo Orienteering club has produced detailed rogaine maps (compiled from orienteering maps) that are CMYK offset printed.

With significant recent interest in colour conformance by the Australian CMYK offset print industry, we should be able to achieve the same results as the Swiss although some effort, and maybe cost, will be required.

CMYK offset colour conformance

Why is colour conformance an enabler? It isn’t in itself. But to me, accreditation to a recognised colour quality mark  indicates the printery is serious about quality, especially repeatability of colour. Unlike PMS with its strictly controlled ink manufacture, CMYK inks and application are relatively uncontrolled and thus exhibit colour variation which may be unacceptable to orienteering.

You also need to be aware that while PMS colours should always be within a narrow tolerance of an internationally accepted  Pantone swatch colour, the best CMYK can achieve is to be within tolerance of a particular quality organisation’s CMYK swatch colours. In other words, switch from one accredited CMYK printery to another and the result could be noticeably different.

Two such digital certifications are from Fogra and Truly Colour (in conjunction with Swiss based UGRA).

Australia CMYK digital (laser)

Since Bushrangers Carnival 2009, Australia has had top flight digital CMYK printing of maps. Similarly to the Swiss development, this came about through research and process experimentation. Reviewing overseas reports earlier this year, it appears we have been ahead of much of the orienteering world in CMYK digital press map production at least until 2012.

Validation of our processes came when 2011’s WRE on Marginata map in Canberra was printed digital CMYK. This was done as the cost of offset printing as normally required was prohibitive. However, despite the print for a rock strewn map being very high for a digital print, it must be noted that feedback from competitors was that it is still unacceptable for such a high level event. This gives some impetus to exploring CMYK offset while awaiting the to see if the advent of ink jet (as opposed to toner based) production digital presses will also bring greater precision.

Two print centres known to produce very high quality digital (laser) print orienteerings maps are;

Specifications and process to enable other digital print centres to achieve the same quality are on the Mapping Resources section of this website. Generally, the model of digital press would need to be ‘full production’ classification and probably will be no more than 3 years old.

Further reading

A further article in the Swiss WOC’12 + OCAD series will be published in the next post.  The topic is LIDAR. The series article on Sprint maps will be published in the March 2013 edition of The Australian Orienteer.

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Comments welcome

Your comments, corrections and own experiences on CMYK map printing are welcome.

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Custom Map Maker, Connie Brown

If you enjoyed any of the books I referred to in recent post Mapping Books that are Not Atlases, then you may be interested in this Wall Street Journal article A Mapmaker Takes on the World. Custom map maker Connie Brown creates maps that reflect the travel, history, even eating preferences of clients (the latter related to her son).

The featured image is by Brad Trent for Wall Street Journal.