cross-section technicalities

Techniques, equipment and issues. Also visit the NSS Survey & Cartography Section.

Moderator: Moderators

Re: cross-section technicalities

Postby Dwight Livingston » Aug 2, 2011 7:01 pm

Actually, if one must show the south-facing section, I'd be inclined to show it as in E below. This more clearly shows that the section has been rotated 180 degrees to be right-side-up, and has the leader pointing across the section in what I think of as the correct direction.

Dwight


Image
***************
Dwight Livingston
User avatar
Dwight Livingston
NSS Hall Of Fame Poster
 
Posts: 323
Joined: Sep 6, 2005 7:17 am
NSS #: 27411
Primary Grotto Affiliation: Baltimore Grotto
  

Re: cross-section technicalities

Postby Extremeophile » Aug 2, 2011 7:51 pm

Dwight Livingston wrote:Actually, if one must show the south-facing section, I'd be inclined to show it as in E below. This more clearly shows that the section has been rotated 180 degrees to be right-side-up, and has the leader pointing across the section in what I think of as the correct direction.

Hmmm. I've never given any preference to what side of the passage I draw the x-section, or what side of the x-section the leader line intersects. I've always thought that the leader line needs to cross the passage in the correct location , preferrably at a right angle, and that the arrow point in the correct direction, but nothing else should matter. The small horizontal line on the opposite side of the x-section seems unnecessary.
User avatar
Extremeophile
NSS Hall Of Fame Poster
 
Posts: 761
Joined: Dec 7, 2009 7:37 pm
Location: Littleton, CO
Name: Derek Bristol
NSS #: 34941
Primary Grotto Affiliation: Colorado Grotto
  

Re: cross-section technicalities

Postby Extremeophile » Aug 2, 2011 8:00 pm

ian mckenzie wrote:
HKalnitz wrote: I have always taught that the tic near the cross section denotes the (vertical) upward orientation of the cross section.


Again, I have never seen that on a cave map. Perhaps I am ill-informed. Can you give us an example of a published survey where the "up" orientation of cross-sections is indicated?

I would suggest that you probably have seen it many, many times, but might not have recognized it as a vertical arrow.
User avatar
Extremeophile
NSS Hall Of Fame Poster
 
Posts: 761
Joined: Dec 7, 2009 7:37 pm
Location: Littleton, CO
Name: Derek Bristol
NSS #: 34941
Primary Grotto Affiliation: Colorado Grotto
  

Re: cross-section technicalities

Postby Bob Thrun » Aug 2, 2011 8:02 pm

Dwight Livingston wrote:Actually, if one must show the south-facing section, I'd be inclined to show it as in E below. This more clearly shows that the section has been rotated 180 degrees to be right-side-up, and has the leader pointing across the section in what I think of as the correct direction.

Dwight
Image

Ouch -- that is an extremely non-obvious symbol convention.
Bob Thrun
NSS Hall Of Fame Poster
 
Posts: 322
Joined: Jul 18, 2006 12:50 pm
  

Re: cross-section technicalities

Postby KeyserSoze » Aug 2, 2011 10:32 pm

Thanks for the replies everybody. Howard I think you cleared up a lot of the confusion. I agree that examples C and D are the correct ones, I was just looking for more confirmation.

Personally I think it would be best to simply flip all of the downward facing cross-sections to point upward so that they line up on the plan view, as with example C. Example C is a whole lot easier to understand and that should be a major priority on any cave map. It was suggested by a fellow caver that the cross-section direction should not be flipped because the arrow is a fixed record of where the caver actually made the drawing. I don't think it should matter which direction you were actually facing when the cross-section was drawn; as long the drawing is an accurate representation of the cave passage then the cross-section could be flipped either way and I would bet that nobody could ever figure out the difference.

I'm also starting to agree that the arrow on the cross-section side doesn't seem necessary for a normal size map, it's just caused a lot of confusion.
This signature is really funny
User avatar
KeyserSoze
NSS Hall Of Fame Poster
 
Posts: 227
Joined: Nov 6, 2007 2:18 pm
Location: Louisville, Kentucky
NSS #: 61069
Primary Grotto Affiliation: Louisville Grotto
  

Re: cross-section technicalities

Postby HKalnitz » Aug 6, 2011 3:52 pm

Excuse me as I go a little anal on this one

I have been teaching how to place cross-section tics the same way for a bunch of years the same way:
1) the tic (or arrow) on the plan side is used to show the direction the sketcher was facing when drawing the cross section (or the viewer of the map when viewing the passage).
2) the tic on the cross section side shows the Vertical orientation of the cross section, typically pointing upwards.


It seems we pretty much all agree on the #1 above, that the tic in the plan of the map represents the direction the sketcher was looking in as the cross section was sketched, and it is up to the cartographer to represent this as he feels best.

However, it seems there was a fair amount of confusion about the #2, the tic representing vertical orientation. At least on person said they have never even seen this. This set me to wondering whether or not I was teaching something no one else did, so I went back and did some research.

I found a mixed bag:
I found many maps with the vertical tic:
One of My maps:
Image

A Map from Stan Allison:
Image

And a Map from Hope and Jeff Uhl:
Image

However I found MANY maps without.
Matter of fact the majority are without the vertical tic:

Hope Uhls excellent Caverna Corredores:
Image

I could find no maps in the new edition of On Station that have the vertical tic

So - did I just make this up? I did some research
In the 1981 version of the CRF manual, I found very specific information about the vertical tic:
Image
I believe this is where I picked up the practice as this is when I started surveying.

However in the 1999 version of the manual, all references are gone:
Image

SO - there has been a standard in the past, but it no longer seems to be supported widely. I would rewrite this as:
Tics in the cross section view can be added to orient the cross section vertically. However if these are not present, one should assume that the cross sections are oriented such that upward direction matches the local vertical of the map in which they are drawn

I would leave you, with one question however
Here is a (made up) cross section, which may represent something in a draft map, that you are handed to help you get to the start of your survey assignment. It has no reference, and is just a small section out of a much larger map (this is a common occurrence at Mammoth cave)
Image

How would you determine which way is up?

Howard
The NSS needs Cavers more then Cavers need the NSS
HKalnitz
Frequent Poster
 
Posts: 75
Joined: Aug 18, 2006 2:04 pm
Name: Howard Kalnitz
NSS #: 20678
Primary Grotto Affiliation: Great Cincinnati Grotto
  

Re: cross-section technicalities

Postby rchrds » Aug 6, 2011 4:13 pm

To begin, I also agree that both C and D are correct.
I never use the vertical tic to orient the cross section, and I always use arrows instead of tics on the side indicating the direction the cross-section is facing.
There is indeed a standard that exists, and that is the UIS cave symbols version 1999, which I try to use as much as possible. If you look at the examples there, you will see that cross sections are described using an arrowed leader line and that each cross section is oriented vertically to the page. This is the key. Though they show their cross sections sitting sort of out nearby the arrow end of the cross-section, normally connect my cross-sections to the other end of the leader, as is the convention in the US, but with only the leader to one side, and not extending past the cross section.

Howard, on your last example, I would submit that this cross section is oriented incorrectly, and should have been drawn vertically with a bent leader line, along with every other cross section on the map. One may or may not choose to add a note in the marginal information that notes this. This becomes even more important when you are forced to show multiple passages at different elevations in the same cross-section. It just makes no sense to have them anything but vertically oriented.

But then I misread your question- I think there are clues that might indicate which way was up- the order of the survey stations (indicating some times which way they were traveling) but probably the most telling is the facing direction the tic indicates- most likely the sketcher was facing down passage (the direction of the tic) and holding the page that way, oriented with the passage, to make the sketching easier, and then drew the cross section as up, facing the way he was holding the page. I agree, this is confusing on the sketch. I have hundreds of similar things going on in Blue Spring Cave, and this is usually the convention I go with.

Jason
Last edited by rchrds on Aug 6, 2011 4:33 pm, edited 2 times in total.
User avatar
rchrds
Prolific Poster
 
Posts: 197
Joined: Sep 6, 2005 8:54 pm
Location: Fayetteville, NC
Name: Jason Richards
NSS #: 41539
Primary Grotto Affiliation: None at the moment
  

Re: cross-section technicalities

Postby rchrds » Aug 6, 2011 4:20 pm

Here is one of the UIS examples, directly from their standards sheet.
Image

Here is an example from the Blue Spring Cave map in progress. Lots of cross sections with different treatment.
Image

Note on the BSC map for you picky folks- I do not add details to sketches for the final map- I am drawing the sketches
as they were originally presented- the sketch quality varies WIDELY. This is why some passage has zero floor detail, and some
has a good amount of floor detail. This wont win me any awards at the map judging, but it's not for you guys. This also give people
a great idea of which passages need to be revisited and resketched. :)

Jason
User avatar
rchrds
Prolific Poster
 
Posts: 197
Joined: Sep 6, 2005 8:54 pm
Location: Fayetteville, NC
Name: Jason Richards
NSS #: 41539
Primary Grotto Affiliation: None at the moment
  

Re: cross-section technicalities

Postby KeyserSoze » Aug 6, 2011 6:16 pm

Wow that Blue Springs map is looking good, I'd like to see the whole thing. The shading for the different levels makes a lot of sense. I'm working on a map right now of a multi-level cave and I might just do the same.
This signature is really funny
User avatar
KeyserSoze
NSS Hall Of Fame Poster
 
Posts: 227
Joined: Nov 6, 2007 2:18 pm
Location: Louisville, Kentucky
NSS #: 61069
Primary Grotto Affiliation: Louisville Grotto
  

Re: cross-section technicalities

Postby rchrds » Aug 6, 2011 7:26 pm

You and I both. So far, 6 of 164 panels complete. Lots of work to do. Shading is tough- it prints different than the screen colors.
User avatar
rchrds
Prolific Poster
 
Posts: 197
Joined: Sep 6, 2005 8:54 pm
Location: Fayetteville, NC
Name: Jason Richards
NSS #: 41539
Primary Grotto Affiliation: None at the moment
  

Re: cross-section technicalities

Postby ian mckenzie » Aug 9, 2011 10:26 am

Another option is to stick all of your cross sections in a separate schedule, kind of like a text-box sidebar, each identified with a letter (A - Z) corresponding to a letter next to its reference line on the survey. The box around the schedule defines the horizontal and vertical planes, and the arrows on the reference lines determine point of view. Useful for complex surveys where there may not be room for cross-section drawings adjacent to passages.
User avatar
ian mckenzie
NSS Hall Of Fame Poster
 
Posts: 549
Joined: Sep 16, 2005 9:40 am
Location: Crowsnest Pass, Canada
Primary Grotto Affiliation: Alberta Speleological Society
  

Re: cross-section technicalities

Postby Extremeophile » Aug 9, 2011 10:40 am

ian mckenzie wrote:Another option is to stick all of your cross sections in a separate schedule, kind of like a text-box sidebar, each identified with a letter (A - Z) corresponding to a letter next to its reference line on the survey. The box around the schedule defines the horizontal and vertical planes, and the arrows on the reference lines determine point of view. Useful for complex surveys where there may not be room for cross-section drawings adjacent to passages.

While a technically valid option, I personally don't like the aesthetics of this approach. It's very time consuming to look at a letter designation on the plan view and then go and locate that letter in some collection of x-sections off to the side. It may be a necessity in a few extremely complex caves, but I've seen it used where I think there was room to place them in the plan view. I would only do it as a last resort.
User avatar
Extremeophile
NSS Hall Of Fame Poster
 
Posts: 761
Joined: Dec 7, 2009 7:37 pm
Location: Littleton, CO
Name: Derek Bristol
NSS #: 34941
Primary Grotto Affiliation: Colorado Grotto
  

Re: cross-section technicalities

Postby ian mckenzie » Aug 9, 2011 12:56 pm

Extremeophile wrote:While a technically valid option, I personally don't like the aesthetics of this approach. It's very time consuming to look at a letter designation on the plan view and then go and locate that letter in some collection of x-sections off to the side. It may be a necessity in a few extremely complex caves, but I've seen it used where I think there was room to place them in the plan view. I would only do it as a last resort.

Some feel that it is aesthetically superior - less cluttered and more organized, and allows the cartographer to better use the empty spaces on the map sheet. It is a matter of opinion and taste (and really not "very time consuming" to look at, though I take your point that it is less convenient). California's 2003 Lilburn Cave Atlas is one of many examples of this style, which BTW also uses double-tick reference lines to indicate point of view.
User avatar
ian mckenzie
NSS Hall Of Fame Poster
 
Posts: 549
Joined: Sep 16, 2005 9:40 am
Location: Crowsnest Pass, Canada
Primary Grotto Affiliation: Alberta Speleological Society
  

Previous

Return to Survey and Cartography Forum

Who is online

Users browsing this forum: No registered users

cron