Hello and welcome to my instructable about an anamorphic sculpture I made whilst at uni. An earlier instructable of mine was made in conjunction with this one. It was for a jig which holds a wooden ball to allow the ball to be cut on a bandsaw.
What is an Anamorphism?
"Anamorphosis is a distorted projection or perspective requiring the viewer to use special devices or occupy a specific vantage point (or both) to reconstitute the image. The word "anamorphosis" is derived from the Greek prefix ana‑, meaning back or again, and the word morphe, meaning shape or form."
In this particular instance I took a wooden ball I found in a charity shop, cut it in half, reduced and arranged it in such a way that the ball maybe viewed either deconstructed or [at a particular point] in its original form.
Step 1: Cut the Ball
The first step was, of course, to find the ball. I bought mine from a charity shop for £1. The first challenge was how to hold the ball safely and securely whilst cutting it. See this instructable for how I did that.
Step 2: Constructing in 3D
Accurately constructing an anamorphic sculpture without 3D computer modelling would be very difficult, if not impossible. As such, I began by modelling the sculpture in Rhinoceros 3D. The sculpture would be comprised of one half of the ball remaining whole and the other half would be cut into slices, separating it at the points where the wood changed.
The way I constructed the sculpture was to first decide on the size of the sculpture i.e. length from viewpoint to the end. I chose to keep one half intact and separate the other half into 4 pieces. This meant I had to position 5 individual elements along the central arm. To determine the positions I went into Rhinoceros 3D and modelled the sculpture.
In Rhino I drew 5 surfaces/planes at an arbitrary spacing and a small circle with the same spacing to begin with to test how I could construct the sculpture. The small circle is where the viewport is. Align the camera so that you are looking through the circle at the planes. Save this viewport. In the perspective view from your chosen viewport, project the circle onto the planes. I found that simply projecting will not work, you must instal a custom script to do this, find it here: project in perspective. This will mean you can successfully project the circle onto the planes and the circle will get larger the further away the plane is from the viewport.
With this basic principle of perspective projection we are ready to give it the dimensions of the ball. I measured the ball with digital callipers and found the diameter to be 90mm. With this dimension I scaled the whole Rhino model construction so that the end circle projection would be 90mm. This means that the final object in the sculpture (the half that will be untouched) is the correct size.
At this point it is worth checking that your viewpoint is no less than 12cm from the first plane since this is the minimal focal point of the human eye. If it is not you should move it and reconstruct the projection.
With the construction at the correct scale and the viewport at a suitable distance it is now possible to construct the ball pieces. Each slice from original sphere should be scaled to match the dimensions of the projected circles. Once this is achieved the result should be similar to the video above.
Sorry if this explanation is difficult to understand, perhaps when I have time I could make a walk through video tutorial.
Step 3: CNC Routing
Once the 4 pieces were successfully modelled in 3D I stacked them one on top of the other in preparation for them to be CNC routed. Since I wanted each piece to retain its one wood colour I had to be careful to position them at the correct height. If I had just stacked them one on the other without considered spacing some of them would have been multi-toned.
Once the half ball was out of the CNC router I carefully cut the individual pieces out from the top down and sanded them.
Step 4: Assembly
To assemble the sculpture I chose to suspend each piece from a piece of brass rod (1.5mmØ). These pieces of rod are pushed into small holes drilled into the bottom of each segment. Refer back to your 3D model to determine the heights and distances from the centre that the piece should be held.
The brass rods are then soldered to a brass tube (8mmØ) that forms the central arm. A small hoop is also placed to encourage the correct position for the perspective to be achieved.
I hope you have enjoyed this instructable, if you have any questions please leave a comment below and I will do my best to answer them. Happy making!