drawing up - seeking advice

[Wookey]

+++ Matt Ryan [04-03-28 03:16 +0800]:
> > Have you got any wise advice how to get the passage
> > walls + other details into a computer in a manageable
> > form?  Hopefully without too much expense on CAD
> > packages!  (Assume I can use unix, or MS windows)
> 
> We routinely draw up A1+ size surveys.  Since what you draw is mostly
> vectors you don't have too much of a problem with memory - you only ever see
> / use part of the scan at once to trace from.

This does depend on the software used. Therion, for example struggles with
larger bitmaps due to the way the underlying laguage handles them. The GIMP
on the other hand does a much better job of managing large bitmaps. Check
whatever you use works before getting too far down a particular path.

> If by any chance you do have the means to scan
> your entire drawn up survey in one 

A large-format copy shop in Cambridge can now do scans of A0 width and
arbitrary length onto CD for < GBP2 per scan. This is a very efficient way
of getting large surveys into a computer. Check out what available in your
locality.

> go then whether or not you cut it up digitally 

The problem with the above is that you get _huge_ bitmaps. I've spent the
last few weeks working with Cobweb cave (Mulu), which is about 1mx3m and
thus is a 13,000 x 30,000 pixel bitmap. I haven't found any editing software
that can cope with this on any of my machines (One with 512MB RAM and 20GB
free managed to load it but you couldn't edit anything in less than a week
:-). Chopping it up into 8 tiles and woking on those has proved fine on a
192MB machine with 1GB disk cache free. (this was supposed to be a quick
hack of the bitmap to avoid converting the whole thing to vector data).

> If you don't mind the VERY steep learning curve then Therion is quite a nice
> way of drawing up caves - allegedly.

I think it's worth persevering with if you know you are going to find a load
more and need to re-do it agian next year, and probably the year after too.

The next issue of CP - due out in the next few weeks - will have a long
worked example showing you how to do an example survey with it.

> FWIW Peak Cavern is drawn up in Autocad and I think Easegill is in Corel
> something or other. 

Easgill is indeed in coreldraw. There wasn't much choice when they started.
Easegill is definately something that would be better done in Therion, but
then they aren't starting now.

> Incidentally, has anyone ever drawn up a reasonable size cave in XFig ?
> I've not played enough to know if it'd be a goer or not but it seems the
> fastest way of tracing passage walls I've ever come across.

No - I've used it for sticking thing together but not for serious drawings.
Does it have a 'trace walls' feature - that would save a lot of time when
converting existing surveys. TunnelX does this, and is also worth serious
consideration.

Oh, and patrick - when you've finished we'll be wanting an article about
what you discovered for CP :-)

Wookey
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