Hey guys, I'm trying to make a fairly simple shape (in 3ds Max) but can't seem to get it. I need a hollow sphere with 64 equi-distant holes in its surface. I just can't seem to figure out the math on this one. If anybody knows how to do it quickly and easily in their modelling software of choice and could make the object and post a link as an OBJ that'd be awesome. Thanks!

no, unfortunately it needs to be a hollow sphere with 64 equi-distant round holes in its surface

drmoreau posted at 3:52PM Fri, 12 February 2016 - #4254687

no, unfortunately it needs to be a hollow sphere with 64 equi-distant round holes in its surface

I read "cube" rather than "sphere". My apologies. Use a Geosphere set to a Tetra Geodesic Type. With just 4 segments. You can create the holes by chamfering the verts. Then subdivide, and spherify.

If you then apply a solidify to the resulting surface, it should result in a hollow spherical object with 64 holes.

don't know how to chamfer the verts, also don't know how to subdivide and spherify. even if I did the problem I run into is how do I figure out the math behind getting 64 holes that are all equally spaced around the surface of the sphere?

i was able to get 24 with boolean operations but couldn't figure out the angles to get the rest into place

Nevermind, that won't work. There's 64 faces, but they may not be equidistant all the way around.

yep, that is the problem I'm running into. figuring out how to make them evenly spread across the surface

drmoreau posted at 3:59PM Fri, 12 February 2016 - #4254692

don't know how to chamfer the verts, also don't know how to subdivide and spherify. even if I did the problem I run into is how do I figure out the math behind getting 64 holes that are all equally spaced around the surface of the sphere?

i was able to get 24 with boolean operations but couldn't figure out the angles to get the rest into place

I'll work on this and see what I can come up with soon. It's a good math problem. I'm thinking the Geosphere is the answer here, but I could be wrong.

yeah I started with a geosphere, then boolean subtracted another smaller geosphere from it to make my "shell". I then ran some rods into the now hollow sphere and was able to get the basics (top, bottom, left, right, and 45 degree variations from there) but could not get to 64.

drmoreau posted at 4:05PM Fri, 12 February 2016 - #4254694

yep, that is the problem I'm running into. figuring out how to make them evenly spread across the surface

Well, to create the holes in this kind of object, you could use boolean, but that's not going to be predictable nor easy, as you're discovering, unless you already have an object with 64 equal sides. To find such an object is the challenge. The only solid I know of that has 64 equal sides is known as a hexacontakaitetragon. I'll do some research and see if we can arrive at that shape with some standard modeling techniques. After you have the object, you simply create the holes in the same way you would a cube or any other object. Just inset the faces, delete, then subdivide. There is a modifier called "Spherify" which will turn any shape into a round sphere if it has enough segments to deform. If we start out with a round-ish solid object to begin with, then it would work perfectly.

The Goldberg Polyhedron family has a variation with 64 equally distant sides. If you can figure out how to get this shape, then you can easily create holes the way Luxxeon was saying, or use the faces to scatter objects for boolean.

https://en.wikipedia.org/wiki/Goldberg_polyhedron#/media/File:Conway_polyhedron_dk6k5adk6k5at5daD.png

SinnerSaint posted at 4:27PM Fri, 12 February 2016 - #4254703

The Goldberg Polyhedron family has a variation with 64 equally distant sides. If you can figure out how to get this shape, then you can easily create holes the way Luxxeon was saying, or use the faces to scatter objects for boolean.

https://en.wikipedia.org/wiki/Goldberg_polyhedron#/media/File:Conway_polyhedron_dk6k5adk6k5at5daD.png

Nice one, Sinner! That has me thinking now. We could definitely generate a Goldberg Polyhedra using the Geosphere primitive, under the Icoa Geodesic Base Type family, in 3dsmax. Now it's just a matter of how many segments will be needed to translate the Icosasphere to a 64 sided Goldberg.

Once I figure out the math, and hopefully arrive at a Goldberg 64 sided polyhedra, I'll post a quick tutorial on how to do it.

that'd be great. it seems like a fairly simple thing to do but in practice it's not so easy, lol.

The more I play around with this, the more I think you're going to need some custom scripting or MCG to get the result you need. There doesn't seem to be an easy solution manually to this one. I've been able to generate a 60 sided geodesic sphere, 72 sides, etc., but the number you require seems to elude standard techniques (at least as far as I've found in the last 20 minutes). I'll keep playing around here, but I feel like this might be one for a clever maxscript, or perhaps a custom polyhedra generator of some kind. If someone else finds a way around it using another package in the meantime, I'm sure we can replicate somehow in 3dsmax. Meanwhile, I'll play around some more this weekend. Do you have a deadline for this?

you said you figured out 60 sided right? that'd be fine honestly.

it's just an illustration for a device in a book and as long as it has "about" the right number of holes it should be fine.

drmoreau posted at 6:05PM Fri, 12 February 2016 - #4254717

you said you figured out 60 sided right? that'd be fine honestly.

it's just an illustration for a device in a book and as long as it has "about" the right number of holes it should be fine.

Oh ok then. I'll put together a short tutorial about how to get that. It really isn't hard. The hard part was in the specific number of sides you needed. I'll post either a short video or screenshots later tonight for you.

sweet, thanks

I don't know if this will fit the criteria for what you're looking for, but this is a sphere with 60 identical holes, distributed in a semi-regular pattern on the surface. This is about the most regular solution you can get with 60 holes of exactly the same size. These holes aren't perfectly equidistant. You can get a perfectly equidistant number of holes only with 4,6,8,12, 42, 92, etc. points on a Icosphere. The reason is that in order to have exactly equidistant holes of the same size, the coordinates of the vertices on the Platonic Solid need to be distrubuted on equilateral triangles which are equidistant to each other. This is only possible with certain numbers of vertices.

So if you'd like to have perfectly distributed holes, each of the same exact diameter, we will need to use one of the possible vertex numbers of the Icosphere.

okay. 42 would work if I could figure that out :)

drmoreau posted at 9:39PM Fri, 12 February 2016 - #4254750

okay. 42 would work if I could figure that out :)

Sure thing. The geosphere primitive has a default Icosa Geodesic Base Type with 42 vertex segments, so it's available by default. All we will need to do is chamfer those vertices, remove the faces, subdivide, and then "Spherify" and "Shell" the result. This is what the object will look like with 42 equidistant holes...

I'll have a video put together for you later. It might take a little bit, because I have to go out for a while this evening, but I'll post it here within the next 12 hrs.

BTW, I responded to your CGTalk request as well. Do you just want this model, or do you want the tutorial? I have the model in OBJ format if you want it. It's modeled to scale in millimeters.

Well, I decided to upload the model for you anyway. Here it is. You can apply another iteration of subdivision to it if you need it even smoother. It's modeled to about 25mm diameter, although the OBJ conversion may not translate properly to all applications. If you need to 3D print this model, I can create a printable STL file for you.

Download it from my file locker here: http://www.renderosity.com/mod/rrfilelock/download.php?fileid=50413&key=6321

Let me know if you need anything else.

As per your request at CGTalk, here's the High Resolution version of this object. This version is about 58,000 quads, but much smoother than the previous version, and should be suitable. Again, if you need a specific size for 3d printing, let me know and I'll make a STL version.

http://www.renderosity.com/mod/rrfilelock/download.php?fileid=50414&key=1655

very cool. thanks.

going to look at some of your tutorials and if you get one up on this object I'll definitely take a look as well.

Very interesting. I remember how to do something like this from a golf ball tutorial I did once.

Here's the video tutorial I promised. Hope you find it useful.

Bucky Ball from John Malcolm on Vimeo.

That looks like one of the plastic golf balls my grandfather used to practice with in the yard when I was young. I followed your tutorial in Blender, and it worked out perfectly. The only difference is in Blender the object is called a Ico Sphere, and instead of chamfer, we would use bevel. My only question is the size of the bevels. Is there a way to tell in Blender the diameter of the holes? I see you using millimeters for the chamfer width in 3ds, and I have my scene set to use metric in Blender, but the bevel is just using the same numbers it always does, regardless of the scene scale? So how do you get precise holes like that in Blender?

HMorton posted at 11:47AM Tue, 16 February 2016 - #4255309

That looks like one of the plastic golf balls my grandfather used to practice with in the yard when I was young. I followed your tutorial in Blender, and it worked out perfectly. The only difference is in Blender the object is called a Ico Sphere, and instead of chamfer, we would use bevel. My only question is the size of the bevels. Is there a way to tell in Blender the diameter of the holes? I see you using millimeters for the chamfer width in 3ds, and I have my scene set to use metric in Blender, but the bevel is just using the same numbers it always does, regardless of the scene scale? So how do you get precise holes like that in Blender?

Many of Blender's internal modeling tools will not display parameters with respect to real world scene units. In other words, creating a bevel with CTRL+B will not show an amount in metric or imperial units (centimeters, inches, etc). I feel this is an inconsistency in the UI that eventually needs to be addressed, but be that as it may, you can still create very precise bevels to specific measurements in other ways. The parameters of most modifiers in Blender do indeed respect the given scene units, and I would recommend using the Bevel modifier for something like this instead of the bevel tool itself. Using the Bevel modifier, you can set a specific width of a bevel to exactly the measurement you need in Metric or Imperial units.

I'll admit, 3dsmax looks pretty accurate. For that price, it better be. There's some cad addons for Blender that I heard were inspired for architecture and stuff. Not sure it will help for stuff like this, but this reminded me of it.

davidstoolie posted at 2:13PM Thu, 18 February 2016 - #4255582

I'll admit, 3dsmax looks pretty accurate. For that price, it better be. There's some cad addons for Blender that I heard were inspired for architecture and stuff. Not sure it will help for stuff like this, but this reminded me of it.

David, in regard to Blender accuracy, there are ways to get very precise results without addons, by modeling to real world scale. One major thing you should take into account is that by default, Blender uses it's own Native Units to measure things, like most applications. So the first step is to go into the Scene properties, and change the Units to either Metric or Imperial. If you use Metric, the system will default to Meters as it's primary unit of measure. This is usually fine for large, outdoor scenes or architectural endeavors, but you can get much more accurate for smaller objects too. Blender, by default, is accurate down to 3 decimal places, although this can be expanded with Python. Regardless, right beneath the main units settings you will see a slider for scale. Adjusting this will multiply the given units of measure to any degree of accuracy you need. For example, change the scale to 0.001 in Metric, and you'll be working now with millimeter units. So you can easily model things within 3 decimal places of 1 millimeter accuracy. That's usually more than enough for things like jewelry, or smaller objects you wish to 3d print, etc. Still, the main problem with using some of the tools is that the parameters will still only display things in Blender default units, so using the modifiers as much as possible for things like beveling will also assist in more accurate results.

LuxXeon posted at 6:11PM Sun, 21 February 2016 - #4255075

Here's the video tutorial I promised. Hope you find it useful.

Bucky Ball from John Malcolm on Vimeo.

That's very simple, but really creative. Amazingly, you get the perfect circular shape with only 1 iteration of subdivision there.