[Therion] Diving LRUD dxf export - Vertical floor/ceiling alignment at scrap joins

[Stephen Clark]

Stacho,

Thanks for the clarification on the 3d modeling. That has helped a lot 
with my understanding of how the output is generated. Even in its 
current form, it is an exceptionally simple way of generating an initial 
model for AutoCAD. I look forward to any improvements to the 3d 
modelling in the future.

The suggestion by Bruce to introduce additional dimension points close 
to the ends of the scraps has reduced the lack of alignment to a few cm, 
which is prefectly acceptable for our purposes. Estimating distance 
underwater, at depth in poor visibility is not very precise! Also, 
adding the points for the same single station to both scraps has 
improved things. I will try the single scrap method, but actually really 
like the ability to use different scale plans of the dry cave sections 
in the same .th2.

Do you have proposals about how the proposed 3d algorithm will work in 
the future? It seems, to me at least, that the ability to introduce 
cross-sectional shape on LRUD data would be even more useful than the 
use of elevation scraps for passage height. I understand this is a 
subject that may get very complicated, very quickly.

I'm a big fan on AutoCAD and am therefore somewhat biased. I have a few 
suggestions for the dxf export that may be worth considering for future 
releases :

1. Export of a closed 3d polyline of the assumed (rectangular) cave 
cross-section at each station on another layer. This x,y,z data is 
already generated for the vertices of the surfaces and would simplify 
over-drawing of known cross-sections and 'working inside the cave' in 
autocad.

2. Export of a 3d ellipse or the current flat floor/arch ceiling 3d 
polyline at each cross-section on a separate layer.  Again, this x,y,z 
data is already calculated. The latest autocad versions have a very 
powerful 'LOFT' command that can seamlessly connect together complicated 
cross-sections along paths.

3. Maybe the export of cross-sections drawn in Xtherion, exported as 
correctly scaled and aligned 3d polylines in the dxf would be a first 
step. The complex triangulation of the surface between two 
cross-sections could be handled by autocad/3dsmax in the first instance.

Excellent software and support. Thank you for your efforts,

Steve Clark