Saturday, December 7, 2013

3D Model: Omnidirectional Jug

Bit of a change in direction for this post. Today I'm going to talk about ceramics. I've had an idea for a jug that I've wanted to make for a long time. The idea is simple in method but complicated in form. The shape I've chosen is an anti-prism or irregular octahedron. The jug will have three handling points and three spouts so that you can grab if from any angle and pour. The idea behind this is that it's a sharing jug.

The design is quite angular but will hopefully be softened on the edges with mild radii. The jug is traditional in purpose but fairly modern in aesthetic. It is my hope to make it using the slip-casting process which I've been researching for some time now.

I've created a 3D model to get a feel for the piece before jumping straight into producing it. There are a number of oddities I encountered in modelling such a complex piece. For the first step I had to make up a spreadsheet to work out some of the geometries of the jug and to determine things like the volume and the ergonomics. I'm confident enough in the ergonomic qualities of the handling points but the volume is a different matter. The spreadsheet calculations involved employing a lot of mathematical formulae that I haven't used for a long time and manipulating them to fit around the calculations required for a piece with such complex geometry.

Enough about complicated equations... lets get started on the actual modelling. The inital stage in modelling the jug involved building a construction sketch. This 3D sketch will essentially constitute the internal space in the jug. As you can see in the images below this was a hell of a "sketch".

As I said earlier this 3D sketch basically makes up the internal space of the jug. So to begin the actual modelling sketches of surface outlines were made tangential to the base of this structure. They were then extruded up the length of the structure in a direction that kept them perpendicular to it.

This was repeated three times around the base triangle. The excess will be trimmed off at a later stage. A further 8mm depth was added on to the bottom of the jug to account for wall thickness at the base. This was also perpendicular to the sides of the jug.

Next the same process was repeated starting from the top to create the other sides of the jug. At this point none of the trimming operations have been carried out.

I'm including this top down view from this stage for no other purpose than it's rather lovely in it's geometric oddity.

The first trimming operations were done from the top of the jug this trimmed the excess material away from the edges that were originally extruded from the base up. The trimming commands followed in the same direction as the extrude commands.

Next the reverse was performed trimming from the base up to remove the remaining excess material.

This is essentially the rough structure of the final jug bar the rounded edges. A base was added and extruded up to close off the bottom of the jug. The two views below show a section view through the jug cut along the planes of separation that will hopefully be used for the casting process.

Finally the edges were filleted both internally and externally and a slight gloss white material was applied to the jug.

I then exported the finished model into Cinema 4D rendering software. I first created a simple scene by adding a basic floor and sky setup. Next I added in 3 omnidirectional lights in an arrangement that I've used before to good effect for simple rendering. Finally I applied a gloss mildly reflective shader to the jug to give it the appearance of white ceramic. For the render itself I used a softening filter and light ambient occlusion. The first render below was created before the addition of the sky and with slightly higher lighting settings.

This is a difficult object to picture without the aid of these sorts of models and even with them it's still a sort of elusive thing. While it always looks like it's leaning one direction it is on face perfectly balanced upright as the triangular top is identical to the base only rotated by 180 degrees.

The next step for this jug is to produce a positive life-size prototype. This is required to make the plaster moulds for the slip-casting process. The jug mould will be split along two of the facets and each side of the mould will essentially be an irregular, rectangular-based, pyramid shape. Hmmm... it just doesn't get easy to explain this shape. But hopefully it's going to be fun to mould. On to the plaster and clay!

John O'Shea

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