wireframe-generating scripts

[Wookey]

I have just spent a while converting a spreadsheet containing an
enormous number of faked-up survex legs to generate a wireframe, into
one which is a more sensible X-Y grid with appropriate altitudes at
the intersections (with a devious index/match function I found on
t'interweb for doing multiple criteria (X and Y co-ord) text lookups).

=if(isna(index('wire mesh'!$D:$D,match(B$5&$A35,'wire
mesh'!$B$1:$B$1000&'wire mesh'!$C$1:$C$1000,0))),"NONE",index('wire
mesh'!$D:$D,match(B$5&$A35,'wire mesh'!$B$1:$B$1000&'wire
mesh'!$C$1:$C$1000,0)))

(doncha just love 'spreasheet' as a language?)

So what I need now is the bit everyone needs - a simple way to turn
such an X-Y grid (containig Z) into a wireframe survex file (or even
the option to gives survex the data directly and it make a wireframe
automagically.)

Does anyone have any code for this? Save the spreadsheet as CSV and
run a bit of perl over it seems the obvious way. I am hoping someone
has already done this...

Anything will do, but desirable features of such a program would be 

1) the ability to not force square grids on people. (co-ords set to
'NONE' in the sheet should cause wireframe lines simply not to be
generated in that area).

2) To add a perimeter line so that the area has non-jaggy edges. 

3) It would of course numebr the X and Y differently so as not to
generate hundreds of loops (which the current crufty solution does).

Wookey
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