Reducing error with large surveys

[Head Back!]

Somewhat related noob question:

I have a real hard time to correlate caves I dove in several times to the maps published in Cave Atlas. How I would sketch out a map to someone who I am describing the cave to would look very different from the map.

Trying to get an idea of a new cave upfront from a public domain map is even more futile.

In contrast, I have well above average skills using topographic and aeronautical maps.

What gives? Are the free maps intentionally crappy to keep cave tourism low or to sell better maps? Is it the complete absence of the third dimensions info screwing my brain up?

*Mods, please delete this post and let me know to start a separate thread if that makes more sense.

[patpicos]

Somewhat related noob question:

I have a real hard time to correlate caves I dove in several times to the maps published in Cave Atlas. How I would sketch out a map to someone who I am describing the cave to would look very different from the map.

Trying to get an idea of a new cave upfront from a public domain map is even more futile.

In contrast, I have well above average skills using topographic and aeronautical maps.

What gives? Are the free maps intentionally crappy to keep cave tourism low or to sell better maps? Is it the complete absence of the third dimensions info screwing my brain up?

*Mods, please delete this post and let me know to start a separate thread if that makes more sense.

some maps are quite accurate...some have had dubious cartography.... care to be more specific?

Ginnie Hancock....top accuracy, a few omissions
LR, low accuracy, TONS of omission
Peacock, high accuracy, low omissions
Madison, high accuracy, medium omissions
Cow, high accuracy (henson map), low omissions
Manatee, good accuracy, quite outdated
Anderson, pretty, but very incorrect
Ruth, understating the cave
...

[Jack Hammer]

Somewhat related noob question:

I have a real hard time to correlate caves I dove in several times to the maps published in Cave Atlas. How I would sketch out a map to someone who I am describing the cave to would look very different from the map.

Trying to get an idea of a new cave upfront from a public domain map is even more futile.

In contrast, I have well above average skills using topographic and aeronautical maps.

What gives? Are the free maps intentionally crappy to keep cave tourism low or to sell better maps? Is it the complete absence of the third dimensions info screwing my brain up?

*Mods, please delete this post and let me know to start a separate thread if that makes more sense.

Water distorts perspective. You get used to it with time.

[Head Back!]

some maps are quite accurate...some have had dubious cartography.... care to be more specific?

Ginnie Hancock....top accuracy, a few omissions
LR, low accuracy, TONS of omission
Peacock, high accuracy, low omissions
Madison, high accuracy, medium omissions
Cow, high accuracy (henson map), low omissions
Manatee, good accuracy, quite outdated
Anderson, pretty, but very incorrect
Ruth, understating the cave
...

I became aware of this issue last week when reading the "Lost in Little River" thread. During training, my buddy goofed at one of the Ts but I could not figure out on the map where that happened. Nothing on this map looked even remotely familiar. That map was not helpful either. And let's not even talk about this one.

Granted, it is over five years ago that I dove LR but on land I have no problem retracing some bush-whacking hikes on the topo map from memory even decades later.

Being utterly confused with LR, I looked at this Ginnie map. There was more of a connect there but the section from the keyhole past the cornflakes to the park bench (where on map?) did not add up. Also the eye and ear depiction even in the side view bears little resemblance to my mental map.

I resolved the keyhole to parkbench issue with this map since my first post. The first map made me think that the keyhole is represented by the lower "r" between the crosshatched areas which is obviously wrong. So, that first map needs arrows for the "Keyhole" and "Cornflakes" comments.

In all three Ginnie examples there is significant vertical change so obviously as I am moving forward in the water going down I do not move as much forward on the map as I think. The flow adds to that mental calibration issue. I would expect these areas to appear "compressed" on the map.

Also, a novice spends a lot of brain cycles in the Ear and Eye running the reel and finding tie offs. I memorized a lot of details that can never be shown on the map at a scale appropriate for the whole cave. My mental recollection of progress is time based and the map is distance based. I get that problem.

Plus our progression speed changed drastically during the class. On the first dive ever in Ginnie we saw the keyhole but could not make it. A couple days later we did Hill 400, Shortcut, Roller Coaster in the same flow. On land I am either fast or slow depending on terrain. There is no way that I get up the same slope five times faster a few days later.

I guess on land there are less mental illusions that are then compensated subconsciously by decades of experience. Under water it's the opposite; no experience to compensate for effects that can significantly skew my mental map.


A big challenge for the cave cartographer becomes obvious when we think about going up high in Ginnie at the beginning of the mainline to stay out of the flow. Up there you are in a 'different world' compared to down where the line runs. How is the cartographer going to depict that?

Which brings us back to the hijacked survey thread. Please PM any suggestion that could help with my mental mapping issue.

[Head Back!]

some maps are quite accurate...some have had dubious cartography.... care to be more specific?

Ginnie Hancock....top accuracy, a few omissions
LR, low accuracy, TONS of omission
Peacock, high accuracy, low omissions
Madison, high accuracy, medium omissions
Cow, high accuracy (henson map), low omissions
Manatee, good accuracy, quite outdated
Anderson, pretty, but very incorrect
Ruth, understating the cave
...

I became aware of this issue last week when reading the "Lost in Little River" thread. During training, my buddy goofed at one of the Ts but I could not figure out on the map where that happened. Nothing on this map looked even remotely familiar. That map was not helpful either. And let's not even talk about this one (I would like the mapping style if it were not for the low quality).

Granted, it is over five years ago that I dove LR but on land I have no problem retracing some bush-whacking hikes on the topo map from memory even decades later.

Being utterly confused with LR, I looked at this Ginnie map. There was more of a connect there but the section from the keyhole past the cornflakes to the park bench (where on map?) did not add up. Also the eye and ear depiction even in the side view bears little resemblance to my mental map.

I resolved the keyhole to parkbench issue with this map. The first one made me think that the keyhole is represented by the lower "r" between the crosshatched areas which is obviously wrong. So, that first map needs arrows for the "Keyhole" and "Cornflakes" comments.

In all three Ginnie examples there is significant vertical change (Why is depth not indicated in the maps?) so obviously as I am moving forward in the water going down I do not move as much forward on the map as I think I do. The flow adds to that mental calibration issue. I would expect these areas to appear "compressed" on the map.

Also, a novice spends a lot of brain cycles in the Ear and Eye running the reel and finding tie offs. So I memorized a lot of details that can never be shown on the map at a scale appropriate for the whole cave. My mental recollection of progress is time based and the map is distance based. I get that problem.

Plus our progression speed changed drastically during the class. On the first dive ever in Ginnie we saw the keyhole but could not make it. A couple days later we did Hill 400, Shortcut, Roller Coaster in the same flow. On land I am either fast or slow depending on terrain. There is no way that I get up the same slope five times faster a few days later.

I guess on land there are less mental illusions that are then compensated subconsciously by decades of experience. Under water it's the opposite; no experience to compensate for effects that can significantly skew my mental map.


A big challenge for the cave cartographer becomes obvious when we think about going up high in Ginnie at the beginning of the mainline to stay out of the flow. Up there you are in a 'different world' compered to down along the main line. How is the cartographer going to depict that?

Which brings us back to the hijacked thread. (Please PM any suggestion that could help with my mental mapping issue.)

I think that the survey accuracy challenge can be resolved by just throwing massive computational power at the problem like Stone outlined first with his scooter mounted mapper and then with the autonomous Sunfish robot. How the resulting point cloud is then presented in an easily accessible and understandable way is the hard part IMO.

***Please delete double post above. I cannot edit or delete that one anymore for some reason***

[apitkin]

I guess on land there are less mental illusions that are then compensated subconsciously by decades of experience. Under water it's the opposite; no experience to compensate for effects that can significantly skew my mental map.
...
Please PM any suggestion that could help with my mental mapping issue.

I think you might have answered your own question.