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Discussion: It always feels bad to blame the mapping

in: ColmM; ColmM > 2023-05-22

May 22, 2023 7:25 PM # 
paulp :
but Irish maps made by British mappers are often quite good e.g. I thought Drumkeeragh was pretty clear, except for some paths I wouldn't have bothred with (mapped by Jon Musgrave)
May 23, 2023 8:17 AM # 
I haven't heard comparable praise for the map but then I didn't run it.....
May 23, 2023 10:11 AM # 
paulp :
I think the biggest issues with that map were from some recent thinning, so it was updated quite quickly in the weeks before the race
May 23, 2023 10:42 AM # 
I mostly mean in general on Irish maps, but did notice it a bit yesterday.
I thought the map was good at IOC, and still mostly did yesterday, it just often feels like things don't quite match up, they're not really wrong, but shapes are often a bit different to how you expect, and don't feel quite right either.
It means everything often feels a bit vague when you're running through it.

I think it felt particularly on my mind given I did a similar session in Scotland on Friday and you could pick out individual knolls and veg changes clearly and lots of things lined up, comparably yesterday even really big crags just sometimes feel a little different when you get there to what you expected, it feels like more work making things fit.
May 25, 2023 7:19 AM # 
I definitely found that Marcus' maps made consistently more sense than other maps.

Next time you are back, choose a small, interesting section of the map, blow it up to 1:5k and walk around some rock/contour features, think how you might map them. It's both an eye-opener and useful technical training (especially when there are more features than will fit on the map).
May 25, 2023 8:06 AM # 
I would agree with that re: Marcus' maps.
Also really agree the walk around would be great. While Cillín and I spoke after the session on Wednesday about struggling to make sense of bits, Cillín did say though before being able to actually criticise it, it does feel like you would need to try walk around and map a section. I think the generalising must be quite hard in some of these areas because, like you say, there are too many features. And in particular - they vary in size a lot so deciding the line between what get mapped and what doesn't is difficult. It does feel like it is managed better elsewhere, but I have done no forest mapping, so I really can't say much.
May 25, 2023 12:12 PM # 
"feels bad to blame the mapping"
Sometimes. It can be used as an excuse for poor orienteering akin to "a bad workman blames his tools". But ultimately maps vary greatly in quality and to deny this would be naive. Some maps suffer from poor legibility while others are just plain wrong. There are renowned map makers used time and again for big international competitions and there are less renowned map makers whose phone doesn't ring.

Remember that two "good" map makers can produce very different looking maps of the same area. Ultimately what determines whether the map is good is whether the competitors can make sense of it. Have you represented the terrain consistently and in a way that can be understood? It is difficult to make maps and requires not only experience but a constantly evolving mindset and a desire to improve. A map I draw today will look very different to the map I drew two years ago because in theory I will generalise better, draw cleaner today than I did before.

In my personal experience in Ireland, I can run on an "easy" map and really struggle to make sense of it, what does this map even want to say to me? Abroad I run on a "hard" map and have no issues with the legibility or representation of the terrain. That says something. Legibility is important and I feel it is an afterthought on many Irish maps, especially since LIDAR has become prevalent. That said in my opinion there are notable distinctions like the maps used at the JK in Northern Ireland, Crohane to name a few. Curious.

"walk around some rock/contour features, think how you might map them"
This touches on something I think is important. It makes sense to me that to be a good orienteering mapmaker you are probably somebody that is also an orienteering competitor (I do not mean elite), has experience on a broad range of orienteering terrains and maps. They have a feel for what they want to see on the map from the runners perspective.
May 25, 2023 12:57 PM # 
blow it up to 1:5k and walk around some rock/contour features
Technically the rules say (or at least said, haven't checked in a while) that all forest maps should be produced for orienteering at 1:15000. 1:10000 maps should just be a blow up of that. If you have to enlarge a map to 1:5000 to understand it, that's a problem and the generalisation should be better. I don't know explicitly about Devil's Glen, but I do know of some examples where this wasn't done (e.g. Lough Firrib).

I talked to Ruth about the Stranahealy map too. There were some parts that I didn't understand at all when I was running, but when I went out to take in controls and was walking they made perfect sense (no. 8 on course 1). This is another question, who should the map be made for? I would think it should be the competitor, who is running somewhat fast.

There was some chat in CNOC about getting in a foreign mapper to do the IOC maps, but it never really materialised for various reasons.
May 25, 2023 10:15 PM # 
"produced for orienteering at 1:15000"... usually field-checked at 1:7500. Add in sketchy laser printing and 1:5000 isn't unreasonable, for the exercise.

There will be distortion. A certain amount is inevitable. Sometimes it is helpful.
May 28, 2023 9:00 AM # 
May 28, 2023 7:28 PM # 
Big Jon:
I used to survey at 1:7,500 for 1:15000 maps (basically that was the scale the pg plot was made at...) Now I usually survey at 1:5,000 - maps are more often 10k now. Base maps are usually digital (or can be scanned) so changing scale is not an issue. At 5k there is more space to fit in little features (and surveyor can be a little less fiddly in the terrain to get things clear). LiDAR plots offer a vast amount more detail than can be shown clearly and so maps tend to have more clutter (another thread entirely - "LiDAR sickness"... Finally maps now are expected to show more detail, orienteers are demanding more detail therefore surveyors have to work to the specification laid down by the clubs/events etc.
May 29, 2023 5:58 AM # 
And yet IOF are still holding on to 1:15,000 as the only approved scale for World Ranking Events, with the additional horror of the new mapping specs with fewer options and more specifics for things like boulders with bigger minimum separation distances all tending to make detailed areas at 1:15,000 uninterpretable and therefore not usable for orienteering.
May 30, 2023 7:48 AM # 
Not usable for IOF WRE races, not unusable for orienteering.

There are areas that are unsuitable for 1:15,000 or even 1:7,500 mapping, yet wonderful terrain for orienteering.

Having now tried my hand at mapping some forest terrain, I can see the benefit/need for minimum separation guidelines (and perhaps specifications). The spots I did that didn't meet the separation specs are the bits I'm not happy with, having seen the printed map --- while drafting, on screen, zoomed in, it was fine.

This discussion thread is closed.