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Re: A few pics

Posted: Thu Nov 07, 2019 6:56 pm
by Robin Adair
Wow! Those are stunning. (Would you be able to post the files?).
Since I’ve just begun making compounds, I haven’t gotten into the fine points of alignment. What I did was to bring the three polyhedrons into a memory slot for each one. My first attempt created one inside of and hiding the other. I realized that I needed to make each a different size, to expose parts of it. I gave each a different color before combining them. I used the mouse to align them, then combined them. When I began to build the model, I realized that I was lucky to get the individual parts aligned as well as they were.
How can I rotate and move the individual parts with better precision than simply spinning them with the mouse? Or is there a better way to do this? I was thinking of taking, say two tetrahedrons, point to point, and “covering” the connection with another polyhedron, perhaps one with holes, showing the connection (just as an example). I haven’t played with the program enough to discover how such things are done

Re: A few pics

Posted: Fri Nov 08, 2019 11:55 am
by marcelteun
Hi Robin,

I am sure you can combine these with Stella by just adding the compounds as described below, but I let Robert answer that, since I am not familiar with Stella.

I uploaded a zip file (temporarily) on my own site with the two models shown:
https://tunnissen.eu/tmp/14_cubes.zip

Re: A few pics

Posted: Sat Nov 09, 2019 5:56 am
by robertw
You want to combine compounds that already have the same symmetry group, then they should be aligned.

Before putting them into a memory slot, make sure they're all the same scale by setting "Scale->Base Polyhedron Radius" to the same value for each.

Re: A few pics

Posted: Sat Nov 09, 2019 5:00 pm
by Robin Adair
I have to admit a bit of ignorance. What is meant by the term “symmetry group”? Or, the mu variable? I took high school geometry in 1971, but haven’t used it much since. I didn’t get into trigonometry much, and have forgotten it anyhow by now. Is there a book I could use to bring me up to snuff in this field?

Re: A few pics

Posted: Sun Nov 10, 2019 10:56 am
by robertw
Hi Robin,

I don't know where you saw the "mu" variable.

You can find "Symmetry Group" in the glossary here: https://www.software3d.com/Glossary.php#symgroup
It's just the collection of symmetries that an object has, eg reflection in a plane, or rotation around an axis.

All I meant was to start with models of the same symmetry. You can see the symmetry group of a model in the toolbar
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Here we see that the current model has icosahedral symmetry, including reflection.

Previously I suggested combining the compounds of 6 and 8 cubes. These compounds both have octahedral symmetry, so they should combine well.

Re: A few pics

Posted: Wed Nov 13, 2019 10:11 am
by marcelteun
robertw wrote:
Sun Nov 10, 2019 10:56 am
I don't know where you saw the "mu" variable.
That he must have picked up from me. For the compounds with rotational freedom I use the angle mu. I think I use the same Greek letter as in "Symmetry Orbits". For one of the compounds I used 6 | S4xI / C4xI | mu.

Marcelteun

Re: A few pics

Posted: Sat Dec 21, 2019 11:34 am
by Peter Kane
Back near the start of this long-running thread, Rob Adair lamented the fact that the pictures in Magnus Wenninger's book are in black and white. I'd have thought that there are enough posted photos in this newsgroup to cover many of them. Wouldn't it be nice to assemble a pdf of these images (subject to receiving permission, of course) ? I suppose a website would be the obvious alternative, but I much prefer the printed page.

Pete K

Re: A few pics

Posted: Wed Jan 08, 2020 12:16 pm
by marcelteun
There are people here who built all of them,.. (Not me, and I have no interest in that either)

Re: A few pics

Posted: Thu Feb 20, 2020 7:10 pm
by Robin Adair
This is a model of Bruckner 23,7 (5,7). I thought I would try tans, browns, and beige. Did this one about two months ago.

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Re: A few pics

Posted: Thu Feb 20, 2020 7:16 pm
by Robin Adair
Here’s a compound of Great Dodecahedron and Great Dodecahemidodecahedron. Basically, I wanted the star placed in what would have been a pentagon, for strength. To do this, I scaled it to where the points of the star met the points of the pentagon.
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Re: A few pics

Posted: Fri Feb 21, 2020 7:05 am
by robertw
Very nice. Those Bruckner models are mostly painful to make!