Stream: brlcad

Topic: spherical sampling


view this post on Zulip Sean (Nov 24 2020 at 18:30):

@starseeker I was working on spherical sampling and noticed you added a sobol sequence generator and related code in libanalyze. That's awesome! Is that exposed/presented anywhere user-visible?

view this post on Zulip Sean (Nov 24 2020 at 18:31):

I want to compare it with another generator I have for incremental spherical sets, use it as a base for convergence testing on closures.

view this post on Zulip starseeker (Nov 24 2020 at 18:55):

It's exposed in the pnts command, IIRC... one sec

view this post on Zulip starseeker (Nov 24 2020 at 18:57):

pnts gen --sobol

view this post on Zulip starseeker (Nov 24 2020 at 18:57):

If you generate points from a sphere using --rand and --sobol, you'll see the difference

view this post on Zulip starseeker (Nov 24 2020 at 18:58):

sobol ended up being of dubious utility for that - it clusters near the poles of the sphere, and I never got deep enough in to see if there was a correction that might be applied.

view this post on Zulip starseeker (Nov 24 2020 at 19:00):

Really should have ripped it out, to be honest - it took a while to find a sobol generator that was appropriately licensed and able to be integrated cleanly, so I hated to get rid of it, but honesty compels me to admit it's mostly code bloat right now...

view this post on Zulip Sean (Nov 24 2020 at 19:02):

clustering near the poles is just a classic mistake in how the random numbers are being used

view this post on Zulip Sean (Nov 24 2020 at 19:02):

the code itself is simple enough and sobol is a useful sequence for quasi-random montecarlo

view this post on Zulip Sean (Nov 24 2020 at 19:05):

I did see a few issues in the code that need clean up, few mistakes to correct

view this post on Zulip Sean (Nov 24 2020 at 19:06):

few things I just don't understand yet (like the next ranges and skip function, the example snippet has typos and comments aren't clear to me yet)

view this post on Zulip Sean (Nov 24 2020 at 19:08):

thanks for the lead on pnts. I'll check it out.


Last updated: Oct 09 2024 at 00:44 UTC