Hi Lynsey,
You've reached the right place, hopefully I can be of assistance. Be aware,
though, that what you ask is quite a complex topic.
So sorry to hear about your conversion difficulties. There are indeed many
tricks to overcome the complexities involved, but there is no set recipe. The
dominant factors that affect conversion success are the tolerance settings, the
structure of the geometry involved, the complexity of any boolean recipes, and
the particular export method being used (they are not all equal).
There are ways to influence all four of those which will affect the output
quality.
For tolerance, most all of the stand-alone BRL-CAD export tools (like g-iges
and g-obj) have flags that let you set the absolute (calculation), relative
(calculation), normal (curvature), and distance tolerance. These have HUGE
impact on quality, conversion time, and success rate. The easiest way to learn
how they work are to take a simple region and play with different settings.
Try setting relative to 10 degree or 1 degree. Try setting absolute to 0.01 or
0.001 (default is 0.0005). There are limitless possibilities.
That said, I'd also suggest not using the g-iges converter as it's one of the
most complex converters in BRL-CAD. The g-obj or g-dxf or g-obj might be a
little easier to manage. Since you mentioned the scripting option, you should
also be aware that we already have/provide a script that converts a .g model
region by region. See the facetall.sh script or the facetize_all_regions
command in mged (which is what the script calls).
That's a lot to hopefully help you get started, but be aware that this is a
complex topic. If it could easily be made turn-key, we would have made it that
a *long* time ago. There is rarely a conversion that cannot success by
adjusting the conversion tolerance settings and model configuration, but
knowing what to change and how to change it is very complicated.
Please reply back with any questions you have. I'll try to answer what I can
and hopefully help reduce some of the frustration.
Cheers!
Sean
p.s. As a glimmer of hope, be aware that we know that we are working to make
this a LOT easier. We've spent years implementing advanced nurbs/brep/step
infrastructure that completely changes the fundamental method of conversion so
that it's much more reliable for export. Advancements are due to be announced
over the next 3-6 months.
On Nov 5, 2013, at 8:15 PM, Johnson, Lynsey E. wrote:
> Hello,
>
> I am writing to request a contact for software support in the area of file
> conversion for the BRLCAD 7.24.0. The g-iges executable command produces
> models with many flaws, and I am wondering if there are any tricks to improve
> the quality of the converted files. My division is in desperate need of
> reliable file conversion, so much so that we are attempting to create a shell
> script that converts .g models by region.
>
> Thanks,
> Lynsey Johnson
------------------------------------------------------------------------------
November Webinars for C, C++, Fortran Developers
Accelerate application performance with scalable programming models. Explore
techniques for threading, error checking, porting, and tuning. Get the most
from the latest Intel processors and coprocessors. See abstracts and register
http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk
_______________________________________________
BRL-CAD Developer mailing list
brlcad-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/brlcad-devel
