Constructing a 'Truncated Icosahedron' in Anim8or.

To Create a SHADO Moonbase Sphere or Soccer Ball

 

Link to SHADO Moonbase Add-on

 

Ever since I was a kid and became interested in 'stuff' space related, I've been intrigued by the SHADO Moonbase from Gerry Anderson's UFO TV Series. It's what every kid growing up in the 1970s though a Moonbase would look like.

Taking a look at the series now in hindsight, the most improbable part of the Moonbase was the landing pad for the Lunar Module - a strange 'trilobite' looking spacecraft that lands tail first on a landing pad mounted on top of one of the Truncated Icosahedron spheres, and supported by a hinged gantry. Setting that aside, the rest of the base looks to be based on reasonable conjecture, though how such a base was constructed or transported to the Moon is left to the imagination. Not having any video or DVDs to hand, I've based my model on photographs I've found on the Web, so I've used a little artistic license in certain areas.

The hardest part was working out how to build the Truncated Icosahedron spheres. In doing so I pushed my knowledge of Anim8or a little further. Hopefully this explanation will encourage other to build bases to their own specifications using Truncated Icosahedron spheres or domes. You can see the progress of the Orbiter add-on here. At the time of writing (May 2007) this there's only the texturing left to do.

Thankfully Anim8or provides a tool to draw a Truncated Icosahedron from scratch. Unfortunately the raw polyhedron created is flat sided and requires some work to achieve a smooth rounded soccer ball shape with indented seams. Bearing in mind that I wanted to keep the polygon count low, so as to be a useable model in Orbiter, the spheres are not a smooth as they could be. I will however point out at the end how a more detailed model can be achieved if you want to use the method for making rendered pictures.

The method outlined below will also work for other polyhedrons.

 

1. Creating the Polyhedron

Begin by opening Anim8or, then selecting from the top menu - Build - Primitives - Tr. Icosa.

Select the Platonic Solids button  on the LHS toolbar and draw a Truncated Icosahedron, which from now on I'll refer to as a Polyhedron.

Re-size as necessary using the Scale button

Then - Center about Origin - Edit - Locate - Center about origin .

You may have noticed that the polyhedron is slightly tilted with respect to the Z  and X axis, as well as in the Y axis. This needs to be corrected if we want it to look level for the purposes of creating something  symmetrical  to the eye.

Go into Right View. Rotate the polyhedron about the Z and X axis in the following order:

  1. Z = - 2 degrees (minus 2 degrees)

  2. x = 10 degrees

  3. Go into Top View then rotate about the Y axis by -11.75 degrees (minus 11.75 degrees).

These numbers were arrived at by trial and error , but there's probably way to calculate the angles more accurately using mathematics..

You may also notice now that the white bounding box that surrounds the polyhedron has now tilted over with respect to the object window grid.

To keep whole thing symmetrical go into Points Edit Mode , select Face Edit    and go into Drag-Select mode .

Now drag your cursor from top left to bottom right so as to select all the faces of the polyhedron. All the faces should turn bright yellow.

Next from the top menu - Edit - Detach Faces, the bounding box is regularized.

Return to Object Edit Mode and ensuring that  the  polyhedron is selected, select the following choices from the Build Menu :

  1. Convert to Subdivided

  2. Convert to Mesh

The Polyhedron has now taken on a spherical shape from which you can just about see the familiar soccer ball facet shapes that we're after.

 

2. Creating the Seams

The next stage is to create the widened seams along the edges of the pentagonal and hexagonal facets.

Go into Points Edit Mode , select Edge Edit    and go into Select mode . We only want to select front edges (edges we can see) so de-select the Back button . Rotate the model as necessary using the Arc Rotate button .

You now need to select all the edges that lie between the pentagonal and hexagonal facets, which can be very time consuming.  There is a way to cut the time needed to do this which I'll explain in the next paragraph. You also need to be in one of the wire-frame edit modes. The best choice of the two is the non transparent one (Center button).

The quickest way to select the required edges is to select the 3 edges that comprise the corners of each and every one of the pentagonal and hexagonal facets across the whole polyhedron.

Then from the Edit Menu - Edit - Select - Quad Loop Select. Voila! all the required edges are now selected.

Next select the Bevel tool and right click and drag anywhere in the drawing window to create a new set of faces (make sure that the faces you create are highlighted in yellow and not blue). Stop dragging the mouse when you are satisfied that spaces you have created between the facets are the size you require. You will notice that the faces that you have just created are curved.

This can be corrected by selecting the Scale tool and right-dragging the mouse with the new faces still selected. Release the mouse button when the edges look straight to the eye.

This completes the section on creating the seams.

 

3. Extruding the Faces

Now you need to select all the pentagonal and hexagonal facets and extrude them to give them a raised appearance from the edges just created.

Firstly ensure that you are in Points Edit Mode , select Face Edit    and go into Select mode . We only want to select front faces (faces we can see) so de-select the Back button . Rotate the model as necessary using the Arc Rotate button .

Begin by selecting the centre faces of all the pentagonal and hexagonal facets as in the diagram below.

Then from the Edit Menu - Edit - Select - Grow Face Selection. All the required faces are now selected.

Next select the Extrude-Connected tool  and right click and drag anywhere in the drawing window to create a set of extruded faces. Stop dragging the mouse when you are satisfied that extruded faces you have created  are the size you require.

Well that's it as far as this tutorial goes for creating a model for Orbiter.  If wanting to only use part of the sphere (such as for the SHADO Moonbase in the introductory picture at the top of this page) it can be cut in two by using the knife tool , then Edit - Loop Cut from the top menu.

See the final result

 

4. Further Detailing

If a more detailed model is required, then with the faces still select after the final operation above, select the Bevel tool once again and right drag to create beveled edges to the extruded faces. Note here that the Bevel tool works on both edges and faces. See the Anim8or manual for more details on the Bevel tool.

By the way in Orbiter it's possible to alter the texture parameters to give a softer edge effect to the extruded faced, so this step can be omitted from a model destined for Orbiter. Next, once again, select the following choices from the Build Menu :

  1. Convert to Subdivided

  2. Convert to Mesh

This gives a very pleasing soccer ball looking mesh, although with a much higher poly-count than the previous version. See Below. If using this method to create a soccer ball the seams need to be a little narrower.

 


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