Discussion: Circle size on 1:10,000 maps

I have always been a little confused about the rules for this. In the ISOM there is quite conflicting information:

"Maps at 1:10 000 must be drawn with lines, line screens and symbol dimensions 50% greater than those used for 1:15 000 maps." In other words, the 1:10,000 circle should be 9mm diameter, and the 1:15,000 circle should be 6mm.

But then in the "Overprint symbols" section:

"The size of these symbols for 1:10 000 maps should be the same as for 1:15 000 maps. However, for multi-age competitions in which both 1:10 000 and 1:15 000 maps are used, the size of the symbols on the 1:10 000 maps may be 150% greater than on the 1:15 000 maps." In other words the size of the circle in a 1:10,000 map should in fact be 6mm, the same as a 1:15,000

Given this conflicting information I generally pick to make them different sizes. I think this makes the most sense, since a 6mm circle on a 1:10,000 obscures detail too close to the control circle. It also means the circle only needs to be cut for one scale. And it basically can be supported by both bits of the rule book since I always seem to have multi-age competition. (which is another imprecise bit of wording - since, to be pedantic, every WOC I've been to has people of multiple ages in it)

Don't be pedantic.

Oh wait, this is one orienteer speaking to another. Carry on!

I think the rules let you take either interpretation. I'll let the discussion tease out the pros and cons...

I've always understood the rule to be that control circles are 6mm no matter the scale.

No, I think AZ has summarized the rules nicely. Both are allowed.

Personally I prefer that the control circles are enlarged with the map symbols when transfered from 15.000 to 10.000 to 7.500. In my head they inform me of the size of the area inside the circle which helps in my orienteering if they´re kept consistent...
When I plan courses I always enlarge the control circles when going from 15.000 to 10.000.

I will have a competitors look on this, and this is just my personal opinion: it does not matter how you interpret that rule, as long as circle does not cover important features necessary for a runner to understand the situation on a run, not standing around, therefore the bigger the circle radius the more things to take into consideration while making cut outs in the circle.

Whatever the case I would like to see it implemented consistently. The vast majority of (forest) races I run are at 1:10 000 and these are almost always with 6mm circles. Every once in a while though the circles are of a different size and this throws me off slightly. Not much but I've built routines based on a certain circle size that have become so automatic that I have to think twice when the size is a different circle.

So if the circle is 6 mm at all scales fine. If it's 6mm at 1:15 000 and 9mm at 1:10 000 and 18mm at 1:5000 then that's fine too (though do circles that large really make sense? - yes I've seen that full range of scales before at o-ringen).

Either way I would like to see consistency. If it was up to me to choose you know which way I'd go.

My favorite argument for 6mm circles is that it simplifies the clue sheet. As the circles get bigger, you need a lot more column C, "Which Feature", symbols. You can even lose features because there are many and you can't specify which one (for example) because no column C symbol is correct. For local events, I sometimes just circle the feature and leave out the column C symbol. I've seen LAOC do it at Vasquez Rocks. On old sprint courses, with the huge circles, it was annoying for half of column C to have a symbol.

I don't like circles bigger than 9mm.

I'm going to check my Condes 9 settings. The last couple of events I printed seemed to have less legible "overprint" symbols (especially the numbers), but it was for sprints where the maps were ISOM printed at sprint scale, so the map symbols were much thicker than normal and the overprint "normal". This is a case where I've considered 9mm circles and 150% line widths.

For ISSOM maps, I'd have to go read the ISSOM again. I think it says 6mm circles, period, but maybe I'll try a few test prints.

@cedarcreek - the consistent clue sheet is actually an argument for making the control circles scale with the map. In fact I think this is a bit of a killer argument.

For events with multiple map scales I think then I think it only makes sense to play safe and scale the circles, otherwise the control description could be wrong.

As for Canadian - I like when the circle is a consistent "real" distance from the control. When I hit the control circle I'm 45m from the control. Always.

Well, unless I have some scale that isn't 1:10 or 1:15 in which case the circle just becomes way too huge and silly. I wouldn't want to go larger than 9mm

The ISSOM specs (2007) for sprint maps of scales 1:5000 or 1:4000 requires a control circle of 6 mm.

I can remember only one major event -- but that's not saying a whole lot -- where a 1:10k map was printed with control circles of 9mm: EMPO's 2010 US Classic Champs @ Moreau. I would guess there are more, but not in my collection.

While at a glance the control circles on the map looked plain wrong, it really was superbly legible, and made sense for the event -- a "classic", on a complex map. Even though I seem to remember it was considered a printing mistake?

@AZ---I'd agree it's a killer argument for a two-scale event, but otherwise, I'm not so certain.

I think it's important to separate the "elite" event choices from the local event choices. The vast majority of OCIN's events are local, with maps of 1:4000-1:10000 most of the time. We have some native 1:15000 maps, and some maps that are really 1:10000 maps, and it's a toss-up whether they print okay at 1:15000. (Some do, some don't.)

It's just been annoying me how silly it is to have a huge, blown-up map with tiny, hard-to-see overprint symbols. I've had at least three people tell me that they love the big map, but they have trouble seeing the overprint. (And my goals are (1) to give the older people every advantage with legibility so there is a young-old competitive atmosphere, and (2) to give the younger people every excuse to run as fast as they possibly can, as training for high-speed orienteering.) I'm going to try both 7.5mm and 9mm circles just to see what it looks like.

One issue I have with 9mm circles is that if controls are close, as they can be in a middle, then the circles are just too big and overlap. I prefer 6mm circles. I've also heard people saying that it can be harder to identify the centre of the 9mm circles.

So if the circle is 6 mm at all scales fine. If it's 6mm at 1:15 000 and 9mm at 1:10 000 and 18mm at 1:5000 then that's fine too (though do circles that large really make sense?

I don't know the exact ruling for foot events but with MTBO, when changing scale from 1:15,000 to 1:10,000, symbols are enlarged by 50%. There are only two symbol sizes available - those for maps at 1:15,000 and smaller or 1:10,000 and bigger - there is no further enlargement/reduction, so an 18mm circle would not happen.

For skiO, symbol scales are nicely summarized on a single sheet:
http://orienteering.org/wp-content/uploads/2010/12...
In the case of control circles, they are 5.5 to 6 mm on all scale maps.

Actually it's the same in MTBO; I was confusing it with track symbols :-)

Diameter of control circles is the same in all scales.

... seriously 18mm circles on a sprint map? Given that it is possible to have controls as little as 15m apart wouldn't that look utterly ridiculous with 18mm circles? The WA sprint champs courses in a couple of weeks would be unreadable with 22.5mm circles - which would be what is "required" at 1:4000.

6mm circles across the board for me.

The wording in the first post doesn't really imply that. It looks as though it's 50% larger going 1:15k to 1:10k but then it stops there.

I'm not referring to 18 millimetre circles on a sprint map. I'm referring to a forest ISOM map that is printed at 1:15k for the elites, 1:10k for the majority of classes and 1:5k for the oldest age classes (85, 90, 95). In a case like that what would you do?

Well that's a good point because the younger age groups would probably also benefit from 1:5,000 - since their courses are so small on the map. But since this is making up rules anyway (to give them this scale) we might as well make up the rule about circle size. For me, for sure it'd be 9mm - like tRicky says, it stops there. But this does suck about the control descriptions, because they might be wrong in the "which one" column (as cedarcreek mentioned)

From a visibility standpoint, I don't think making the circles bigger makes much difference. Making them thicker would help. I've spent several seconds at the start trying to find the overprinting at all. It might just be my age (57) and colorblindness (partial), but just a few more pixels of thickness would help. I tried to look up the ISOM and ISSOM specifications, but IOF's website is not responding (as usual.)

The wording in the first post doesn't really imply that. It looks as though it's 50% larger going 1:15k to 1:10k but then it stops there.

Not really. The basic meaning of the rules quoted by AZ is that overprint symbols should be the same size irrespective of the scale - so 6mm circles for 10 000. There is an exception - when you have both 15000 and 10000 maps used for the same event you can have 150% overprint symbols on the 10000 maps (9mm circles). My understanding is that this exemption was included to make things easier for setters/organisers - so that they don't have to have worry about different control descriptions or circle breaks for the different scales, a problem that has been raised in this thread.

But at an event where all the maps are printed at 10000 (a middle?) then the only choice, according to the rules, is overprint symbols that are NOT enlarged by 150% (6mm circles).

When I read both the paragraphs quoted by AZ it is clear that the overprint symbols are a special case and should not normally be enlarged like all the other symbols.
Perhaps, given the confusion that is apparent on this thread, the first paragraph should be amended to read: "Maps at 1:10 000 must be drawn with lines, line screens and symbol dimensions , with the exception of the overprint symbols, 50% greater than those used for 1:15 000 maps".

An interesting aside. At a Canadian event quite a few years ago, I was reviewing the control descriptions (given out ahead of time in those days) with my junior orienteers, and I noticed that the same control had quite different descriptions on each of two courses. (I expect the description sheets were done independently using Clue or something similar - in those days we didn't have multi-course planning software like condes and purple pen). Not wanting the kids to be confused (and one course to have a "wrong" description), I mentioned it to the organizer. For my trouble, I was promptly berated that I shouldn't be "comparing clue sheets". I guess they thought I was intentionally looking for common controls and legs (which a lot of people did in those days, but was definitely not my intent). A little later, the organizer did come back and admit that one description was incorrect and a correction was posted at the start.

Anyway, it sure makes it nice that now you can describe a control once and have it automatically be fixed for all courses that use that control.

I suspect that the newest versions of these software packages probably now or soon will have functionality that would let you modify the description for different courses printed at different scales.

In any case, I think the right thing to do for an important event is to make sure you screw up as little as possible, so if you're thinking of using 9mm circles for all courses, or some combination of 6mm and 9mm depending on class or course, then make sure you attempt it ahead of time.

I've done events with 1:15000 elite maps and 1:10000 for everyone else, but always with 6mm circles: 2005 Team Trials Long, the 2013 Relay Championships---the Jr-Jr was a different scale, and I think a few more. I really like it to be as simple as possible, with as little "new learning needed" as possible. I usually wrap the courses, then split or fork the course file into a 1:10000 branch and a 1:15000 branch and cut circles and verify clues (esp the Column C) for each one. It's a lot of work, and any errors in the courses have to be fixed in both branches.

Condes 9 seems to have the right tools to handle this, but sometimes I'm not certain how to ensure cutting a circle is only for one canvas, or multiple canvases. It's worth checking it out with local events before you do something important.

Anyway, I really think bigger circles are a worthwhile experiment, but please consider the hassle and make choices in the interest of quality control. (Imagine stress and severe sleep deprivation.)

Just to hijack this thread a little bit and follow-up on what origamiguy hints at, what if the Start Triangle was mad bigger and bolder? Personally, I'm fine with the control circles either way but it would be nice if the start triangle really jumped out.

If you use 150% circles, then the start triangle, finish circles, connection lines, and numbers are all 150% as well.

What robplow said.

I don't know that I've run at an event that used three different scales before.

@carlch - At Swiss O Week, the organizers posted a blank map that had the start triangle printed in the correct place at the -1 minute line. I found this to be very helpful for knowing where to look when I flipped over my own map directly after, and think it's a nice detail that could be added to the start procedure of other events.

We put up a blank map with the start triangle on for our summer series 'scatter' events, which also gives people the opportunity to discuss 'possible routes' (even though it's scatter).

SOW also allowed you to look at your map in the final minute before you started. Very nice as you did not have that whole "where the **^^ is the triangle" after the final beep

@LOST_Richard, elite classes had to wait until the start beep before looking at their maps. It meant I was often run over on the way to the start triangle as I searched for #1 and tried to plan the leg.

Letting people look at the map for a minute before the start seems like a nice way to reduce the stress (increase the fun?) for less serious or less experienced runners. I like getting the map at the start myself but I can see that it would be nice for many.

One minute for MTBO but that's mainly so you can stick it in the map board (and then plan a route).

three different scales

I started doing that for local races, as the beginner course can be blown up to 1:5k and I think seems easier than squinting at a playing card sized part of a 1:10k map. Then some courses in the middle fit at 1:7.5k.

It's not always great to just blow up a map to a larger scale. Especially for beginners. We had a situation at a local meet where maps for White and Yellow were printed at a larger scale, but this ended up cutting the legend and important catching features off of the map. We had a number of folks on Yellow who fell off the map and took a long time to recover.

I like to keep the circle at 6mm, but I have increased the lineweight of the course overprint before to make it more visible on a detailed map.