Very cool, but Error "Index was outside the bounds of the array."

Hi,

I am intrigued by Pachyderm. Thanks for creating and sharing it.

Oddly, I am experimenting with not a room but a portable semi-transmission-line speaker enclosure. I want to see what's going on in it.

The Pachyderm case is pretty much a boilerplate tutorial thing, largely copied from Gediminas Kirdeikis's excellent videos.
: https://www.youtube.com/watch?v=t9t5jnw6XTk

I made truncated copy of the speaker cone, and divided it, evaluating the surface and creating vectors and normals to run the simulation. The surface is offset the speaker cone so that there's nothing co-planar.

It does solve, but it works with only about 100 sound sources. I wish I could see the wavefront a little better. Increasing the bounces makes it go wrong, as well, with the following error.
"1. Solution exception:Index was outside the bounds of the array."

Also, I tried adjusting the voxel grid depth. Set to on zero, it doesn't run. Other values don't seem to help the problem.

Is there is anything I could set to get more rays or bounces without throwing an exception?

I've added blurry Cloud objects, and set the gradient transparency, but what other kind of visualization should I be doing for the most fun--err, um most helpful data assessment for further consideration?

Thank you.
--BrendaEM

Attachments:

Pachyderm.jpg, 944 KB
Pachy02small.gh, 18 KB

Replies to This Discussion

Permalink Reply by Arthur van der Harten on November 19, 2022 at 5:37am

Hi Brenda,

Well, first off, I don't know Gediminas Kirdeikis. He never communicated with us before making that video, and there is a lot that we would have recommended he do differently, in order to keep from misleading people.

First off, sound is not like light. The wavelengths are much larger, which means it will not behave like light when an object is smaller than the wavelength. A more sophisticated study would be needed in that case, such as with the finite volume method in Pachyderm. I assume that a speaker enclosure would fall into that category. It's fine if you are just experimenting, but please understand that you probably can't expect accuracy in this case.

Second, have you tried with Pachyderm for rhino's animation tools? "Pach_animation" the particle animations in that tool actually trace the evergy of each particle, and doesz nearest neighbor searches for each particle so they can share everyone when there is focusing and superposition. It can probablu also do not trays because we aren't using grasshopper for brute force operations, which is usually pretty inefficient and can introduce problems.

To your other questions, I don't know why it won't do more than 100 bounces. Maybe I hard coded a limit to keep people from getting stuck in a loop. It's usually not useful to see more than a few bounces at once, if using this tool as intended.

Regarding the voxel grid depth, the voxel grid is there to optimize the ray tracing, so that it doesn't take forever. The rays visit boxes in a grid, and only the geometry that intersects that box is checked for an intersection. No voxel, no geometry to check... Please set at least 1 if you feel you don't need a voxel grid.

Arthur

Permalink Reply by Arthur van der Harten on November 19, 2022 at 5:41am

Sorry for the typos. That third paragraph should read:

"Second, have you tried with Pachyderm for rhino's animation tools? "Pach_animation" The particle animations in that tool actually trace the energy of each particle, and does nearest neighbor searches for each particle so they can share energy when there is focusing and superposition. It can probably also do more rays more effectively because we aren't using grasshopper for brute force operations, which is usually pretty inefficient and can introduce problems."

Permalink Reply by Brenda EM on November 19, 2022 at 7:39pm

Thank you for the reply, I will experiment with different pachyderm modes.

Though, I apparently also am not allowed very many sound sources. What I hoped to do, was offset the cone from the speaker cone, and use that subdivided reference object for creating equally distributed normals.

Respectfully, I feel that the tutorial's creator was trying to help people.

Permalink Reply by Arthur van der Harten on December 1, 2022 at 5:25pm

Hi,

There shouldn't be a limit on the number of sources, but each source adds another simulation, which can really add up in terms of ram memory. Maybe it has something to do with grasshopper. However, if you use the Pachyderm for Rhino animation tool, you should be able to have as many sources as you like. (How many did you want?)

Respectfully - regarding the tutorial's creator - perhaps he was trying to help. I don't have a problem with that. I do have a problem with having to correct his mistakes - which is the position I'm in in this thread. In the meantime, others have done very good tutorials, and they are good because they worked directly with us. I helped Isak Worre Foged, and I did it without asking for anything in return. Seek out his tutorials for a much better understanding of how these tools should be used. I don't know why GK has never reached out to me. As it is, his tutorial teaches at least one serious untruth about scattering. Now I have to clean that up when I run across it, or people who make mistakes using that information will blame me for that. (This has happened once already.)

Arthur

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