# Issues with Pachyderm - looking for a tutorial

Good morning everyone. I’m trying to simulate the acoustic performances of an environment using Pachyderm, both in Rhino and in Grasshopper, but I am not able to find any tutorial about it.
I wrote to Arthur, the man behind Pachyderm, who has been so kind to share with me a couple of GH definitions (one for the study of the sound reflection, the other one to evaluate the acoustic comfort in different points inside a room), but when it comes to modify them according to my needs, I’m lost!

The green element is the pavillon which has inside the sound source (linked to a point), the big red volume around the pavillon is an arena, and both of those elements are linked into the “Grasshopper Geometry” inside the Polygon Scene element.
This is the first problem, because the Polygon scene asks me also for the Rhino Geometry, which wasn’t asked into the Arthur’s example. In addition, I don’t know where to take it, because if I draw a geometry on the canvas and I relate it to multiple elements and/or I internalize it, it becomes a Grasshopper Geometry.

Also, I don’t understand why, when I try to link a surface to the Surface input of Divide Surface, it tell me “Data conversion failed from Brep to Surface”.

Any suggestion? I cannot find any tutorials for this kind of modeling, does anybody have some to share?

I also have troubles with the Pachyderm simulation in Rhino. Once I bake the pavillon and the arena and I set them in meters, then I insert the sound source and the sound receiver, then I assign proper materials to each object in the scene, the results from simulation looks weird to me:

In both cases, the sound source is a geodesic speaker which emits 200W, and the microphone is placed at 50 meters.
More than 150dB?
And the result doesn’t change between the first and the second simulation, but in the first, around the sound source is placed the acoustic pavillon that schould amplify the sound, while in the second one, the speaker is simply placed in the middle of the arena.
I followed step by step the tutorial of Pachyderm for Rhino that you can find on the Pachyderm website.

Thanks!!!

I think @Arthur is the man knowing more about this subject.
You can also still post questions in the Pachyderm group: http://www.grasshopper3d.com/group/pachyderm

Arthur

Hi,

First off, there are some old instructions on the website (http://www.perspectivesketch.com) which I suggest you look at if you haven;t. Video tutorials are in progress right now, thanks to a generous user.

So the scene components have 4 inputs. The first (RG) is a boolean. You set it to true to have it grab all visible, baked surface/brep geometry from the Rhino model, or false to ignore the Rhinoceros geometry. The next prameter is GG. This is where you drop any surface or BREP geometry from grasshopper. Note that materials in Pachyderm are set by layer, and grasshopper geometry does not have layers… which brings us to the next parameter, GL. Here, you indicate an integer for every piece of geometry, which corresponds to the index of the layer where pachyderm will find the material properties you want applied to your grasshopper geometry. Just make sure that the number of integers matches the number of surfaces or breps, and that they are both in the same order.

The last parameter (VG) is just a parameter indicating the depth of the spatial partition system. Choose a high number (7 or so) if you will be doing lots of ray-tracing on the model, or a low number(2 oe 3) if you will be changing the scene a lot and will be doing a relatively low amount of ray-tracing.

Regarding your results, I would make sure you are using enough rays. For an outdoor scene, you may need to pump the number of rays up very high… perhaps in the millions. Because they will not bounce around very much, you will find that the calculation time is probably still reasonable.

kind regards,

Arthur

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Hey,

I’m trying to figure out how to use Pachyderm too. Looking for a tutorial, or way better, a reference.

I wanna compute the ETC (in order to get the reverb, the early decay time and every subsequent analysis working) but end up with a problem to build the stationary receiver. It asks for a Srcs, i can only bring an Src and I’d hoped for more success.

Any clue ?
And if I may ask @Arthur for some example files, I’d be glad to have them to accompany me in my researchs

Thanks in advance !
Have a nice day

PACH_1. Essais Pachyderm.gh (17.7 KB)

Hi Ant,

Try the attached
.Open Office.3dm (289.0 KB)
Office Noise Display.gh (16.8 KB)

Arthur

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Hey,

Thx a lot for these files, got to understand pachyderm a bit more.

Then I’ve got a new question @Arthur : I bet the Power (P) [The power spectrum for the source (0=62.5, 1= 125 … 7 = 8000)] input to the Geodesic Source is in dB and the 8 step range correspond to frequencies in Hz.
If I’m right, is it possible to broaden this spectrum to have a range from 20Hz to 20kHz ? May using the Loudspeaker object instead of a Geodesic one more suited ? (in fact, I’m not sure of which to use in which case).

→ I’d like to compute the Spaciousness criterion right after

I do hope I’m right with the units
Regards,

PACH_1.2. Essais Pachyderm.gh (39.3 KB)
PACH_1. Essais Pachyderm.3dm (277.3 KB)

Hi,

It wouldn’t be appropriate to broaden the settings beyond the frequencies of 63 to 8k. You would seldom find material data for those frequency ranges, and the geometrical analysis techniques are not terribly useful at extreme low frequencies (63 Hz. is even a stretch).

The loudspeaker object is used when you have a CLF file, for loudspeaker directivity. (see http://www.clfgroup.org/)

For spaciousness, you will probably be looking at Lateral Fraction or Lateral Efficiency. You can also listen to the room’s spatial qualities if you use Auralization in the Rhino plugin. (I’m currently working on some improvements to auralization, so you might want to wait about a week for that).

Arthur

Hey,

Ok, it’s true that the only material acoustic references I’ve seen range from 125Hz to 8kHz (Vörlander 2007). I’ll dig in some articles to better understand that.

Yé, saw your tutorial, thanks for the link

I’ll look for that, I’ve never heard of these descriptors, I was thinking about Apparent Source Width (ASW) and Listener Enveloppment (LEV) as they are described in the annex of ISO 3382, which shall soon be renewed as it was written in 2008-2009, acoustic science has evolved since then.

I’m looking for that, just tried my first auralization.

Thanks a lot for all these information, I’ll be happy to share models and definition once my work is over
and like the solution processor says “Have a Nice Day” !

I’m sorry for the late reply, but my PC was enjoying an holiday to the technical service!

Weel, thank you sooo much! You solved all my problems!

@Arthur will be presenting TGIC’s upcoming webinar on using ‘Pachyderm Plugin for Room Acoustics Simulation in Rhino/GH’.

Definetly going to attend!

This might not be 100% relevant to your question, buuuut, my friend Isak just uploaded a whole podcast series on Architectural Acoustics, several of which deal specifically with Pachyderm, that may help.

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Thank you!