Course Overprints

[Wayward-O]

One of my other hobbies is photography and for the last few years this has been Digital. One of the pillars of digital photography workflow is fidelity of colour at all stages. I keep my computer screen calibrated and the computer is in a room with daylight bulbs to minimise variation in the ambient light colour temperature between daylight and artificial.

I use a ColorVision Spyder 2 to calibrate my screen. This has been superseded and the current ColorVision Spyder 3 is available for <£100. Also, both software and hardware calibration solutions are available for calibrating printers. Most digital photographers use only a few different papers and stick to the manufacturer’s inks, having a different printer profile for each paper.

I don’t think that we need to go to quite this extent, but by borrowing some of the techniques employed by digital photographers may help us maintain more accurate colours in our maps.

[70plus]

Partial transparency - that was something we lost when we swopped our John Bull sets for OCAD. JB sets could produce horrible results in careless hands, but equally they could produce a fine pink course which let everything on the map show through.

But there should be more unformity - with JB sets it was down to the experience and care of the user. Now we get different shades of red/magenta/purple, and very different line widths and circle sizes - also (I guess) largely down to user inexperience and care, but sometimes caused by producing two map scales. Control circles and leg lines are rarely cut to reveal detail, and sequence numbers are not moved to less obstructive positions. But if the task becomes a chore, the result is often less than satisfactory.

[LesS]

Well, I've solved my problem and should change the topic to Contact Lenses.

I was aware I had no trouble drawing my route on after the event - with specs on. On my second post I had been going to try to put bits of the 3 reference maps from I was using to show the variations from Routegadget (even if I didn't know how) - but they were all pretty much the same - with specs on. Must be the high-def screen I thought. Dig out the maps - what's the problem - they're still all pretty much the same.

Nowadays, I only wear lenses for O, right eye reading, left eye distance. For those not in the know, the brain works out what's going on and compensates - shifting between the required eye without you being conciously aware of. It's not for everyone, and with the general age-deterioration in vision, I did try to increase the strength of the reading lens but the brain didn't like it so I had to revert to a lower strength.

Anyway, sat at a table, lenses in and look at the maps. What map!!! Much to my surprise, the problem was not the reading lens but the distance one which of course presented a totally blurred image that totally swamped the detail from the reading eye. Conciously, using the right or covering the left, the course overprint was obvious. Under normal conditions, the lenses go in half an hour or so before the start for which time the brain does only long distance work, favouring the left eye and the right effectively shuts down. Never look at the maps in the start lane - I've looked at the old maps before the event - so on picking up the map, even peering with the right eye, I just can't pick up the course. This would also explain why the course becomes clearer as I go round a course as the brain adjusts to what it's supposed to do with each eye.

On my reference maps, I had not realised before, but they had different backgrounds - on the generally open moorland with a yellow background, the course appears bright red and is easily seen - albeit on that map, the couse had not been scaled down for the 1:10000 so everything was larger than usual. On the open forest map with white background, the course disappears into the contours - too much red in the brown? On the dark green with many clearings and rides, a turmoil of shapes and colours (Auchingarrach!!) the eye just takes ages to separate things out but even with specs on, it's not easy.

So at the end of the day, I'm going to have to find a method to get the reading eye working before I get to the map, but that's my problem!! So, thanks to everyone for focusing my mind on what was actually happening rather than concentrating on the effect.

[mappingmum]

Damn! I''m never going to be able to beat you now Les

[AndyO]

On contact lenses, I used to use the "left eye distance, right eye reading" principle, when I wore varifocal specs everyday, and it wasn't bad. I found, as you have, that the brain seems to process the monocular information and I was able to switch between reading and distance well.

A few years ago now, my optician offered to let me try varifocal contact lenses, because I did not find varifocal glasses comfortable to wear, as you had to continually turn to look directly at what you wanted to see otherwise you were not looking through the right part of the lens. To my delight this has proved quite successful, and for everyday use I can see to read and use them for distance as well, at least in good light. My prescription is pretty bad (right = -8.75; left = -4.75) so the range is challenging, and in poor light (ie indoors) I need reading glasses as well.

For orienteering, I sometimes use O glasses, but it depends on the area and the scale of the map. 15k no chance, 10k OK if the area is not to complex, 7.5k fine.

[LesS]

So I literally wandered round my course yesterday - nice clear course overprint - when it struck that though I might have solved my difficulty in reading the map when I first picked it up, this did not address the red/blue-grey aspect of the problem.

Pondering afterwards on whether my lenses had, say, an anti-glare film that was doing a filter, I was told that my lenses were blue anyway!!!!!!!!!!!!!!!!! Now THAT could explain blue-grey if the red in some ink mixtures had been filtered out by the lens.

A call to the optician's receptionist confirmed that this was a 'handling tint' - I remembered the days when they were totally clear and, if dropped, could never be found again - but could not possibly be affecting my colour vision - shows how little I know - and I must see the optician to be checked out, so appointment made.

And mappingmum, I have even more bad news for you - after joking with the start officials that this course would be TD1 compared with last week's Scottish, I proceeded to take the tourist route round the course, leaving the second control at the time the winner finished and, though improving, making further errors to the extent that I was laughing at myself by the end. I have now used up my next six-months supply of errors, so you'll have to wait till next year now to beat me.

[LesS]

My optician tells me that the blue-grey handling tint will affect the wavelength by a quarter of a wavelength and would not be discernable however, because contact lenses are so much more precise than specs, the focal point may not always fall precisely on the retina and this may exacerbate any problems.

The major problem is the distance and reading lenses. Even though I think I am reading with my right eye and can feel all the muscles working as I go from looking at a distance to close up, the left, distance eye is still working very hard and continues to deal with colour. It enhances green to the detriment of red and the stronger the reading lens is, the more powerful this effect will be. She reduced the power of my reading lens, and immediately the 'red' overprint became much more pronounced. Unfortunately, I couldn't see any detail on the map anymore!!

This also explains the course disappearing into contours - the red difference is no longer powerful enough - and also why the overprint on the dark green of Auchingarroch can't be seen even though it can be against the white.

Given the info 'distracted' gave about the 100% magenta ISOM standard which I assume was used on the British Champs courses with which I had no trouble compared with the what I assume is the spot colour printing that causes the problem - my optician said that this sort of mix of colours would definitely make the problem worse - I have to ask why the ISOM standards aren't being adhered to - they presumably put much time, effort and money into defining the standards. But I have no knowledge of this aspect of O, so there must be a reason - cost?

I could go back to specs, but the constant flow of sweat, condensation and buildup of salt makes the map extremely difficult to read even if for the first five minutes it is far better than lenses. So I'll live with the problem and just hope that ISOM overprints are used more often.

[70plus]

LesS says ".. affect the wavelength by a quarter of a wavelength .." Uh?? To this ex-chemist/physicist this makes no sense. It sounds like saying something is twice as hot as another. Explain? (I don't want to start an arcane discussion)

[distracted]

Given the info 'distracted' gave about the 100% magenta ISOM standard which I assume was used on the British Champs courses with which I had no trouble compared with the what I assume is the spot colour printing that causes the problem.

The other way round, LesS - the British used spot colour litho and the correct purple colour, OCAD uses the "incorrect"/non-optimal 100% magenta. Apparently when the ISOM spec was written, people didn't print using CMYK colours so the lack of match between the two colours probably wasn't a worry for them. But as you've shown it obviously affects the readability - and some guidance from the experts as to the best CMYK match for PMS purple to use in OCAD would be really useful.

[DeerTick]

My optician tells me that the blue-grey handling tint will affect the wavelength by a quarter of a wavelength and would not be discernable

I think your optician's conclusion may be correct

(See

http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract

and

http://www.ncbi.nlm.nih.gov/pubmed/937486 )

but not his reason.

LesS says ".. affect the wavelength by a quarter of a wavelength .." Uh?? To this ex-chemist/physicist this makes no sense. It sounds like saying something is twice as hot as another. Explain? (I don't want to start an arcane discussion)

Sorry. You have

AP

[Wayward-O]

In ISOM:2000, ISSOM:2007, etc., PMS numbers are provided for all colours EXCEPT the purple overprint. In the table ( ISOM:2000 Page 8 ) providing CMYK colours for each orienteering colour, purple is given as 100% Magenta, with no Cyan, Yellow or Black. Therefore IMO, orienteering overprint purple IS 100% Magenta and the use of PMS Purple is not to ISOM.

[distracted]

A PMS colour chart is available here:

http://www.hookedonpromos.com/Pantone_Coated_CMYK.pdf

Plenty of named colours in the last two lines, including PMS Purple - a defined shade in its own right. CMYK equivalents for 4 colour printing are a recent edition, as outlined here:

http://homepage.ntlworld.com/mapping/is ... tindex.htm

[jac]

I'm going to have to find a method to get the reading eye working before I get to the map.

Warmup. Before you start your run, you warm up for running. So warm up for map reading: bring a map segment (or your loose control descriptions) and 'read' it on the run.