Discussion: When is a feature not a feature?
in: Orienteering; General
Sep 11, 2006 8:23 PM
#
I enjoyed the Gorges Goat in NY this past weekend and wanted to inquire about an aspect that was my undoing in the event...
Two controls were about 2cm apart on a forested (white) hillside of a 1:15000 (or so;-) scale map.
I counted two streams between the controls and thought it would be a count of about 200 right strides...
Clearly I was the one in the wrong, but after about 80 or so, I reached my second stream and started looking around, mostly in a curious fasion. Shortly thereafter, two other competitors reached that point and also started taking actions to look around - making me think I was close to where I wanted to be...
Many of you are now thinking - oh yeah...
The thing I did was get off count and start to question where I was based on streams that are not "on" the map... The others seeing me looking around also got off track (momentarily). In reality, I was hardly half way there.
[The thing that really got me in trouble though was trying to re-set where I was instead of just following them - I could have followed one or the other right to the control eventually instead of heading off on my own... (goat event - allows following of course...)]
After the event, one of the wiser runners at the meet commented to me that there were more than 2 streams between the controls, and with that, I understood how I got off track.
Looking in the map with clear light and my reading glasses, I see some little blue squiggles in the area - perhaps that is one clue, but the question I have for this group is - when is a feature not a feature? (There must have been 5 streams there)
In other locations, where there is a trickle of water, it's called a stream.
When are multiple features "folded" together, or are there features like streams that unless they are wider than 2 feet are ignored?-)
Perhaps with boulders, a single boulder is significant, but a group may be less - but there is a designation for lots of boulders, not one for lots of streams!-) [and perhaps with recent rain, some would normally be mostly dry and were unusually full of water that day]
I'm thinking this is very much an "experience" thing, and now that I have gotten burned by it, I will be more alert in the future, but any advice (or commiseration) appreciated.
steve
Two controls were about 2cm apart on a forested (white) hillside of a 1:15000 (or so;-) scale map.
I counted two streams between the controls and thought it would be a count of about 200 right strides...
Clearly I was the one in the wrong, but after about 80 or so, I reached my second stream and started looking around, mostly in a curious fasion. Shortly thereafter, two other competitors reached that point and also started taking actions to look around - making me think I was close to where I wanted to be...
Many of you are now thinking - oh yeah...
The thing I did was get off count and start to question where I was based on streams that are not "on" the map... The others seeing me looking around also got off track (momentarily). In reality, I was hardly half way there.
[The thing that really got me in trouble though was trying to re-set where I was instead of just following them - I could have followed one or the other right to the control eventually instead of heading off on my own... (goat event - allows following of course...)]
After the event, one of the wiser runners at the meet commented to me that there were more than 2 streams between the controls, and with that, I understood how I got off track.
Looking in the map with clear light and my reading glasses, I see some little blue squiggles in the area - perhaps that is one clue, but the question I have for this group is - when is a feature not a feature? (There must have been 5 streams there)
In other locations, where there is a trickle of water, it's called a stream.
When are multiple features "folded" together, or are there features like streams that unless they are wider than 2 feet are ignored?-)
Perhaps with boulders, a single boulder is significant, but a group may be less - but there is a designation for lots of boulders, not one for lots of streams!-) [and perhaps with recent rain, some would normally be mostly dry and were unusually full of water that day]
I'm thinking this is very much an "experience" thing, and now that I have gotten burned by it, I will be more alert in the future, but any advice (or commiseration) appreciated.
steve
Sep 11, 2006 9:04 PM
#
Nick:
it depends. sometimes one can encounter issues like that ( especially on blue colour on the map ). it could be the difference in season when was mapped vs. when is a competition taking place. usually marshes and stream they have a certain degree of appearance, during the year, muddier in spring , late fall, drier in summer. that's for blue, as for green ( getting thicker woods ) or yellow colour, require to pay attention to how old the map it is , and also what season was mapped or the event taking place.
could be for black( roads) the same case ( lots of leaves in the fall on a small path will be almost invisible if crossed over ). at least that is how I treat things,
plus the scale matters a lot. 1;15000 is very hard to put too many things, but the excuses above are.. better
could be for black( roads) the same case ( lots of leaves in the fall on a small path will be almost invisible if crossed over ). at least that is how I treat things,
plus the scale matters a lot. 1;15000 is very hard to put too many things, but the excuses above are.. better
Sep 11, 2006 9:09 PM
#
feet:
To be fair, it has been somewhat wet in the Rochester area recently, and the streams are relatively high right now (for example, there was an extra pond SE of control 16). That means some unmarked ones show up, particularly in steep terrain like Letchworth, which is probably wetter than usual for this time of year. The map is a static representation of reality, while the seasons change. I think this is just an 'experience' thing.
However, the one thing you probably can learn is that on many maps, mappable streams are determined by a combination of their bank size (if there's a ditch, map it) and their permanence (if it's there in a dry year, map it). Vegetation also plays a part (if there's swamp vegetation there, it needs to be mapped somehow, and then sometimes it looks more stream-ish than marsh-ish. Or something like that - it's up to the mapper.
The GorgesGoat was a nice event and hopefully more people will come in the future when it doesn't conflict with Pawtuckaway.
edit to add: that is, I mostly agree with Nick.
However, the one thing you probably can learn is that on many maps, mappable streams are determined by a combination of their bank size (if there's a ditch, map it) and their permanence (if it's there in a dry year, map it). Vegetation also plays a part (if there's swamp vegetation there, it needs to be mapped somehow, and then sometimes it looks more stream-ish than marsh-ish. Or something like that - it's up to the mapper.
The GorgesGoat was a nice event and hopefully more people will come in the future when it doesn't conflict with Pawtuckaway.
edit to add: that is, I mostly agree with Nick.
Sep 11, 2006 9:46 PM
#
I think the best way to come to grips with this is to actually do some mapping. It will quickly become apparent that what makes mapping hard isn't getting stuff in the right place, but deciding what gets mapped, what doesn't, and how best to represent things.
What's the difference between a linear marsh, seasonal watercourse, and stream? Depends on the mapper. When does white become light green? Depends on the mapper. Are those three distinct boulders or a boulder cluster? Depends on the maper.
Once you have been forced to make these decisions yourself, you'll come across things that are mapped differently and just say, "well, I would have mapped that different" rather than "I must be off!" Of course, sometimes you really are off, so don't completely rule that possibility out.
In addition to checking how old the map is, also make a note of who did the mapping. Every experienced mapper develops a personal style which includes not only their interpretation of the IOF mapping specs, but also feature density. Some mappers like to get as many features as possible on the map. Others (such as myself) prefer to keep the map readable and are quicker to generalize features. It's an art, not a science.
What's the difference between a linear marsh, seasonal watercourse, and stream? Depends on the mapper. When does white become light green? Depends on the mapper. Are those three distinct boulders or a boulder cluster? Depends on the maper.
Once you have been forced to make these decisions yourself, you'll come across things that are mapped differently and just say, "well, I would have mapped that different" rather than "I must be off!" Of course, sometimes you really are off, so don't completely rule that possibility out.
In addition to checking how old the map is, also make a note of who did the mapping. Every experienced mapper develops a personal style which includes not only their interpretation of the IOF mapping specs, but also feature density. Some mappers like to get as many features as possible on the map. Others (such as myself) prefer to keep the map readable and are quicker to generalize features. It's an art, not a science.
Sep 11, 2006 9:48 PM
#
On a related note: the presence of several competitors searching for a control is NOT an indication that you are close. Quite the opposite: it probably means the control is not nearby (which is why nobody's found it).
Sep 11, 2006 9:53 PM
#
Gil - no, this was #13 to #14. #16 had a different issue, but then I was following along with Pete...-)
Sep 11, 2006 10:00 PM
#
feet:
13 to 14 was the best 'keep concentrating all the way' route on the course, but I have to say that if there were extra streams there (I think I remember one), they didn't bother me because I was reading the contours and rock (which are much more reliable) instead.
Sep 11, 2006 11:50 PM
#
Gil:
I had almost the same problem as described by Steve going from #15 to #16. Two streams should have been crossed and I mistook wet depression as second stream however I made a 45 degree angle directional mistake coming out of #15 that added to confusion for me.
There is no such thing as perfect O-map. O-maps are subject of subjectivity of the mapper. Sometimes there are legit reasons why certain features are skipped on one map but similar feature will be mapped on some other map/location. For example - some maps are filled with rootstocks and only 5M high rootstock will be mapped as distinct features. However you might find 1M high rootstock mapped on different map (Letchworth vs. Cobbs Hill for example). As long as it is consistent within a map - I don't have a problem with that.
Overall I am grateful that there are folks who take upon task of mapping. It is such a tedious task to produce quality O-map. I was co-author of one O-map and honestly - I am not looking for co-authoring another one in near future.
Given opportunity I'd like to thank all the former, current and future mappers for all the hard work they put in so the rest of us can enjoy sport of orienteering.
And I agree with Feet - some mapping "inconsistencies" can be identified with more experience.
There is no such thing as perfect O-map. O-maps are subject of subjectivity of the mapper. Sometimes there are legit reasons why certain features are skipped on one map but similar feature will be mapped on some other map/location. For example - some maps are filled with rootstocks and only 5M high rootstock will be mapped as distinct features. However you might find 1M high rootstock mapped on different map (Letchworth vs. Cobbs Hill for example). As long as it is consistent within a map - I don't have a problem with that.
Overall I am grateful that there are folks who take upon task of mapping. It is such a tedious task to produce quality O-map. I was co-author of one O-map and honestly - I am not looking for co-authoring another one in near future.
Given opportunity I'd like to thank all the former, current and future mappers for all the hard work they put in so the rest of us can enjoy sport of orienteering.
And I agree with Feet - some mapping "inconsistencies" can be identified with more experience.
Sep 12, 2006 6:26 PM
#
It is also the job of the course planner to "test" his courses and make sure that they are not using features that are not on the map or making sure there aren't any extra features/unmapped features on the most sensible route to a control.
There was an event years ago in Canada where the course setter had to go back on the map and remap corridors where the courses were going so he could stick to his courses - the map was quite weak. That's of course more work than moving your control to a more fair location. You could also warn people at the start that there is an extra stream between let's say control 4&5. People will not remember that information but when they realise that something is wrong, it might ring a bell and they will recall hearing somethng about an extra stream.
But for all of that, the courses have to be tested.
There was an event years ago in Canada where the course setter had to go back on the map and remap corridors where the courses were going so he could stick to his courses - the map was quite weak. That's of course more work than moving your control to a more fair location. You could also warn people at the start that there is an extra stream between let's say control 4&5. People will not remember that information but when they realise that something is wrong, it might ring a bell and they will recall hearing somethng about an extra stream.
But for all of that, the courses have to be tested.
Sep 12, 2006 6:57 PM
#
Gil:
Course setter would have to run the same way as competitors would to catch every "extra" feature between controls. Given that there could be 2-3 or more slightly different route options I am not expecting course setter to check everything in between controls. Obviously it depends of type/rank of the meet. More diligent route checking should be performed for A-meets in NA vs. club meets.
Sep 13, 2006 3:57 PM
#
This i think is a tough one. I know for a fact in some areas were i run the decision is quite varied. Boulders in particular can be a problem. In a rocky area to decide wot to map can be difficult. Some mappers willmap themif they are over a certain height and one in particular will only map them if they are above the groung, ie. you can see partially under them rather than them being in the earth.
I agree that the season the map is made in is very important depending on the season as some areas which are dry can easily be marsh in the wet season and vs.
I agree that the season the map is made in is very important depending on the season as some areas which are dry can easily be marsh in the wet season and vs.
Sep 13, 2006 4:14 PM
#
Any course setter that doesn't identify and test EVERY reasonable route for EVERY leg at an A-meet is negligent. (And, yup, it's a lot of work, but it's also running through the woods which is supposed to be what we like to do).
For local meets, I usually know the map well enough that I can lay out courses that avoid the problem areas without a lot of field checking. That said, I'm not sure from the account given that there was a problem in this case. As has been noted, it's been wet, so competitors should expect to see more water than mapped and 80m is a lot different than 300m. If the extra stream came just 50m before the real one, that would be a problem.
For local meets, I usually know the map well enough that I can lay out courses that avoid the problem areas without a lot of field checking. That said, I'm not sure from the account given that there was a problem in this case. As has been noted, it's been wet, so competitors should expect to see more water than mapped and 80m is a lot different than 300m. If the extra stream came just 50m before the real one, that would be a problem.
Sep 13, 2006 5:38 PM
#
There is a distinction here somewhere. If a tree falls at Pawtuckaway, doesn't the runner just go around it? I'm used to terrain where there are fewer mapped features, and more certainty that runners will be in a particular place on the map, perhaps in a gully that provides an easy climb. If that gully has a brand new 6 foot waterfall that's not on the map, then there is a problem. Perhaps at a map like Pawtuckaway a similar problem would be if a tree fell and blocked the high ground between two marshes making the route around better than the route between.
By Eric's standard, I'm somewhat negligent. I check what I think are likely routes, and in particular "chokepoints", but I trust the map more than I probably should. The worst-case example for a bad practice is having two easy-to-set controls on two ridges perfectly placed (with close parking for ease of setting, of course), and to never check the "map-to-terrain correlation" for likely routes crossing the reentrant of death between them.
By Eric's standard, I'm somewhat negligent. I check what I think are likely routes, and in particular "chokepoints", but I trust the map more than I probably should. The worst-case example for a bad practice is having two easy-to-set controls on two ridges perfectly placed (with close parking for ease of setting, of course), and to never check the "map-to-terrain correlation" for likely routes crossing the reentrant of death between them.
Sep 13, 2006 5:55 PM
#
Gil:
I will argue definition what is "reasonable route". What is reasonable for one might not be totally unacceptable for other. Years ago I knew the guy who'd come up with route choices that nobody else would see. His unconventional route chouses were key for winning numerous races. He was one of the slowest elite runners I knew. Also I knew guy who was extremely fast runner and always choose safest routes even if it meant running half more then everyone else would. He did not care about making mistakes because he would compensate them with his speed.
Those two guys were total opposites from each other, used totally "unreasonable" route choices compared to "mortals", but bottom line - they both managed to win races
Any sport is about innovation, trying to find new ways how to win, get an edge over your opponent. All the greats of any sport were innovators.
I am not implying that course setter should not check route options at all. Actually – if you think about it - it would be an option in ideal world and with ideal O-maps. However in real world course setters should apply some common sense regarding route checking depending on how familiar course setter is with that particular area.
Those two guys were total opposites from each other, used totally "unreasonable" route choices compared to "mortals", but bottom line - they both managed to win races
Any sport is about innovation, trying to find new ways how to win, get an edge over your opponent. All the greats of any sport were innovators.
I am not implying that course setter should not check route options at all. Actually – if you think about it - it would be an option in ideal world and with ideal O-maps. However in real world course setters should apply some common sense regarding route checking depending on how familiar course setter is with that particular area.
This discussion thread is closed.