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Drawing multiple levels

PostPosted: Jul 6, 2012 8:35 am
by GroundquestMSA
I just finished a survey of a very small multi-level cave. In trying to decide how to represent overlain areas, I looked at other examples of multi-level maps. Most used a dashed line for the lower level and then include a detailed aside. I didn't think this method was suitable for my purposes since there would be no clear way to distinguish between level 1 and the section of level 3 that was not overlain. Also, since I sometimes struggle to add detail to the maps of the small featureless caves that I often map, a detailed aside of an overlain section would look pretty much the same as the dashed line plan view.
Despite reading an old Compass & Tape article that denounced the use of color to represent levels as foolish and bizarre, I decided that it would be the easiest, most understandable way.

Please have a look at this map and tell me what I can do to improve its overall appearance. I honestly think it's hideous. The upper level is floored with clay and the lower two with cobble, but I can't include floor detail without obscuring other passage or taking the levels apart.

Re: Drawing multiple levels

PostPosted: Jul 6, 2012 9:16 am
by trogman
In spite of what the Tape and Compass article said about using color, I think it is a fine way to show different levels. I remember seeing Bill Torode's map of Fern Cave, AL, that was drawn using multiple colors . If you know anything about Fern, it has many, many levels, and the multi-color method was probably the best way to distinguish the levels.

Your map is fine, and is certainly not "hideous." However,one thing it does need is a label clearly showing where the entrance is. I am guessing it is where the "0 datum" label is, but for clarity's sake it needs to be marked.
Another possible method to use is an idealized profile view of the entire cave. This can show the various levels of the passages, and is probably easier to do with a cave that is relatively straight, like this one is.
I am curious why you chose to have north inverted. Perhaps other cartographers can weigh in on this, but my practice has always been to have north aligned with the page and pointing up. One map that I am familiar with that has it pointing down is very confusing to use in the cave. Every time I use this particular map, I have to constantly remind myself that it is inverted and should be read upside-down.

Trogman :helmet:

Re: Drawing multiple levels

PostPosted: Jul 6, 2012 9:36 am
by GroundquestMSA
Thanks Stephen,
The map is upside down simply because that's the way I sketched it in the cave, starting at the entrance. The caves I survey have no need of a map as a navigational aid, so I usually try to lay them out on the page with the entrance on the bottom or on the left (the way my eye personally prefers to travel) and then let north fall where it may. I know that's not the "proper" way to do things, but in these cases there is no practical objection.

A profile would indeed be nice, but I didn't do the detailed sketching needed to create one while in the cave. I may go back and sketch the more vertical sections for a profile and then use my passage dimensions to recreate the rest. Still, I want to have a plan view included on every map, and while this one may be understandable, it could sure use some improvement.

I am only a little familiar with Fern Cave, AL. I would like to see that map. It's a bit comical that this little cave has the same name (I didn't name it).

Re: Drawing multiple levels

PostPosted: Jul 13, 2012 8:09 am
by UnderGroundEarth
Not sure if you are on Facebook, but if so the Survey & Cartography Section of the NSS has just created a group on there that is a great forum for finding out information and asking questions. ... 280860864/

Re: Drawing multiple levels

PostPosted: Jul 14, 2012 12:27 am
by Jeff Bartlett
In this instance -- mind you, having never seen this cave -- I'd say the middle level isn't significant enough to warrant an offset. However, it's critically important that your profile show the relationship between these passages, and a good cross-section at that spot wouldn't hurt. It looks like that part of the cave is an important element of the route your map user will travel, and it would appear that story is best told with some view other than the plan view.

In instances where there are multiple, complex levels atop one another, offsets are a well-accepted standard practice. You can also try showing each level discretely; Dwight Livingston's excellent map of Shovel Eater Cave is an extreme example of this. I've attached a screen capture from a recent map of mine where I tried to show three levels individually, but even in this instance the profile and cross-sections are crucial (and likely easier for the map user to parse).


Re: Drawing multiple levels

PostPosted: Jul 14, 2012 8:31 am
by GroundquestMSA
That map is a wonderful thing Jeff. I can't see the cross-sections or profile but it's still very understandable (exceptpng the absence of pit depths).

I agree that my map doesn't need an offset. I think a profile view would be the best way to go. Still, the plan view is going to be there too, and I need to improve its appearance. I'm a bit jealous of your little decorated cave. Mine has absolutely zero notable features.

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 11:48 am
by Roppelcaver
In Roppel, I draw levels in discrete layers (Illustrator); the passages within each layer masks those below it. Where this has become useful is providing versions to folks in PDF format. Each layer can be clicked on or off to view the levels of interest, and printed if desired. The PDF UI provides an easy way to snap on and off levels, and with the layers constructed correctly the user can see different perspectives of the same map

I had chosen a utility approach for ease of use (and for my laziness in drawing). This avoids the issue of how to represent all the levels on a 2-dimensional surface -- arguably a cheap and non-artistic way around the problem, but does the job. From my perspective, the challenge of drawing 4-8 levels that may interleave vertically exceeds my abilities.

I will try to post something to show what I am talking about

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 2:16 pm
by Bob Thrun
Your map has a zero datum (at the entrance?), but no other relative elevations. It is like giving the altude of sea level, but not of any mountains.

I like the way you show the relation of the levels with shading. The Ojo Guarena map book does something similar with dashed and dotted lines. It first shows all the levels' walls with a confusing mix of dash-dot patterns. Then it has pages for each level with only the outer boundary shown by a dashed line. I like your shading better.

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 4:54 pm
by GroundquestMSA
Bob Thrun wrote:Groundquest,
Your map has a zero datum (at the entrance?), but no other relative elevations. It is like giving the altude of sea level, but not of any mountains.

Very good, thanks. Since I plot everything by hand, I usually scribble 0 datum on my line plot just to help ensure I don't get turned around and start working off the entrance. I put the station #s far off to the side so they don't get in the way and sometimes ignore them. I typically change it to Entrance on the map.

I'm going to re-do this little thing tonight. Hopefully a few of you can let me know if the new version is improved.

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 5:19 pm
by Jeff Bartlett
GroundquestMSA wrote:(excepting the absence of pit depths)

They're in there. p43, p27. Also listed in the portion of the legend at upper right.

One interesting point here, though, is that a cave like this is explained so much better by the profile view(s) that I actually put the profile at the top of the map instead of the plan view. It's always instructive to see how difficult it is to interpret a cave map when two of the three views are absent, no matter how much work has gone into the plan view! Whatever the technique you choose for representing multiple levels in your plan view, make sure the transitions between each and the relationship of the levels to one another is adequately expressed in your profile and cross sections.

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 6:35 pm
by GroundquestMSA
Jeff Bartlett wrote:They're in there. p43, p27. Also listed in the portion of the legend at upper right.

So they are, my apologies. I'm not accustomed to seeing them written like that, and the legend led me to look for the good old pit depth in a box.

Re: Drawing multiple levels

PostPosted: Jul 17, 2012 8:17 pm
by GroundquestMSA
Ok, here's my second attempt. I decided that the little bit of the lowest level that is overlain didn't need to be shown at all. I put the middle level against a grey outline of the other two. This allowed me to add floor type. I also added a basic extended profile. I wanted another cross section at the second drop, but I somehow failed to draw one in the cave, and I don't want to make it up.
Someday I will grow up, move on from Paint, and have a map with clean lines.

Re: Drawing multiple levels

PostPosted: Jul 19, 2012 11:43 am
by Chris Chenier
GroundquestMSA wrote: I also added a basic extended profile.

The profile does add good information to help understand the cave, but this is a projected profile, not an extended one. Projected profiles have projection angles (its the profile along an imaginary plane, as viewed perpendicular to that plane). An extended profile is one where the azimuth of the shots are disregarded and the cave is "stretched" horizontally. Extended profiles are appropriate with mostly single-passage and represents well what one experiences when travelling through the cave. Il also allows to represent all shots on the profile whereas in a projected profile, if a shot is close to being perpendicular to the projection plane, it does not appear on the map.

Re: Drawing multiple levels

PostPosted: Jul 19, 2012 4:12 pm
by GroundquestMSA
Chris. It's an extended profile.