Stream: brlcad

Topic: path tracing


view this post on Zulip Sean (Dec 18 2020 at 18:41):

/me attempts to revive adrt_slave

Our simulation needs are starting to exceed rt's current capabilities... need a working path tracer...

view this post on Zulip Sean (Dec 18 2020 at 18:42):

oh and related, @starseeker any way to get facetize to not decimate the heck out of what it's working on when it's in a fallback mode?

view this post on Zulip starseeker (Dec 18 2020 at 18:44):

--decimation-feature-size can be used, but I don't recall the semantics of how it behaves offhand. I think it's a scale factor compared to feature size...

view this post on Zulip starseeker (Dec 18 2020 at 18:45):

let me do a quick test... stand by

view this post on Zulip Sean (Dec 18 2020 at 18:45):

I'm currently running things like: facetize --feature-size .0003 --max-time 9999 newbot region

view this post on Zulip Sean (Dec 18 2020 at 18:46):

I usually just get "Continuous Meshing: Fatal error, could not find crossing!"
CM: surface reconstruction failed: region
CM: continuation polygonization surface build failed.

view this post on Zulip Sean (Dec 18 2020 at 18:46):

No feature size succeeds, but I go from 200k poly to like 5k poly and it's unusable

view this post on Zulip starseeker (Dec 18 2020 at 19:05):

OK, --decimation-feature-size with smaller values should produce bigger meshes.

view this post on Zulip Sean (Dec 18 2020 at 19:05):

different from --feature-size?

view this post on Zulip starseeker (Dec 18 2020 at 19:05):

Yes. This was my test:

mged> facetize --CM --feature-size 0.06 --decimation-feature-size 2.0 ellipse.r ell_06.bot
CM: completed in 16 seconds with size 0.06
CM: completed in 23 seconds with size 0.054
CM: timed out after 30 seconds with size 0.0486
CM: successfully created 6960500 faces, feature size 0.054
CM: decimation succeeded, final BoT has 104 faces
mged> facetize --CM --feature-size 0.06 --decimation-feature-size .01 ellipse.r ell_06.bot
CM: completed in 16 seconds with size 0.06
CM: completed in 23 seconds with size 0.054
CM: timed out after 30 seconds with size 0.0486
CM: successfully created 6960500 faces, feature size 0.054
CM: decimation succeeded, final BoT has 247642 faces

view this post on Zulip starseeker (Dec 18 2020 at 19:07):

Frankly I really don't like those settings - they're just direct exposures of numerical inputs in the underlying code, IIRC, and they're both sensitive and unintuitive.

view this post on Zulip starseeker (Dec 18 2020 at 19:08):

IIRC "decimation-feature-size" is the one from the "new" decimation routine - I should probably go read the paper to try and get a better feel for what it's doing

view this post on Zulip starseeker (Dec 18 2020 at 19:13):

In the long run, once we've got proper plugins-as-executables in place, I'd like to look at setting up some of the alternatives (CGAL, libigl) that might be slower but useful fallbacks - license considerations are a stopper for CGAL as-is, but with plugins as executables we might have more options.

view this post on Zulip Sean (Dec 18 2020 at 19:22):

I'll give that a try, thank you

view this post on Zulip Erik (Dec 22 2020 at 02:07):

I think if you're looking for the distributed aspect, it may be worth reconsidering mpi. Particularly if it's going to run on ib equipped clusters.

view this post on Zulip Sean (Dec 22 2020 at 21:09):

we're just trying to get something that reliably doesn't result in error.

view this post on Zulip Sean (Dec 22 2020 at 21:10):

I didn't mind it taking 24 hours the first pass, more impressed that it was initially a good result. Its this second pass that's destroying it via decimation.

view this post on Zulip Sean (Dec 22 2020 at 21:13):

/me tried facetize --CM --feature-size .006 --decimation-feature-size .001 tip2.r tip3.bot ... actually fails very quickly now

view this post on Zulip Sean (Dec 22 2020 at 21:14):

oh, promising, .0006/.0001 ...


Last updated: Oct 09 2024 at 00:44 UTC