Micro-computer rostrum control

Thoughts on micro-computer rostrum control and still being able to afford to eat. Introduced by Mike Joyce.

Mike Joyce at the controls.

To some people, making animation films is about rough scribbles turning into polished drawings full of movement and life. But to me this is only part of the fun. I am lust as excited by the whole process of film making; the juxtaposing of close-ups and long shots and the pacing which editing gives; the use of pans, zooms and rotation; the use of quick dissolves to give a soft flow to the images.

In larger animation studios, all these tasks are generally segregated and given to specialists. The rostrum cameraman solely thinking of moving his table and column as smoothly as possible and not primarily being concerned with what a six-frame hold looks like on the screen.

Being someone who likes to perform all aspects of the production and not wishing to be tied too rigidly to a dope sheet when shooting, I used to imagine sitting at the rostrum table and panning and zooming over my drawings while thinking creative thoughts and trying to improvise with cels and cut-outs. I soon realised that trying to do all this at the same time as calculating fairings, and making sure that in a diagonal pan all the axes meet, was causing a brain explosion.

Yes, I had heard of computer controlled rostrums, but until recently the cost of the hardware and software made the systems viable only to the ‘commercials’ and special FX end of the market. With the advent of relatively cheap and powerful home computers costing around
£300, I thought: surely these could drive my rostrum? Naively, I hadn’t appreciated all that was involved in getting any computer to ‘talk’ to motors mounted on rostrum drives. Help was at hand when I made contact with Ron Bicker and his R.D. Systems at Bournemouth. Ron is an ex-documentary film cameraman who has adopted the role of eccentric-boffin and builds a whole variety of animation motors to drive any camera, as well as custom designed computer control systems.

He has now provided me with motors to drive the East/West and North/South axes, the table rotation, zoom lens, camera drive and fade/ shutter. These work on instructions received from Ron’s magic box that translates signals from my Commodore 128 computer. His colleague Colin Osborne has written software, i.e. the computer program that enables me to enter the shot length in frames, the distance that each axis is to move the required fairing. All the calculations are over before I can even think of putting the kettle on. I can then sit at the rostrum table and think only of manipulating the artwork while the system pans, zooms or spins in single, double or continuous frame mode completely under the control of the computer.

Also, it can automatically make single or continuous dissolves, and has a cel-cycling routine to speed up filming.

R.D. Systems range from £2,000 to £9,000.

Ron Bicker and Cohn Osborne now talk in more detail of their system.

From time to time some genius proclaims a re-invention of the wheel. Rostrum Automation is hardly that, rather the idea of gaining more precise control of the movement of all the wheels to be turned. Most animation rostrums have their principal axis (N/S, E/W, zoom, rotate etc.) controlled by wheels with handles for manual operation, and a positional setting obtained by reading divisions on a vernier scale on the wheel of perhaps 100 per full turn, with turns being recorded by a veeder counter. As you know to your cost, all these settings have to be doped out first, and then applied frame by frame, much time having been taken up with calculating ‘fairings’ and other gradual changes of movement.

The first step towards automation is to fit motors on all the setting shafts normally controlled by handle wheels. The most effective type is the stepping motor, which is made in a variety of sizes and power. Motors can be attached directly to the end of the shafts or indirectly by sprocketed belt drives. Typically the motors have a resolution of 400 ‘moves’ per revolution, or more if they are geared up’ via sprocketed belt. Even at 400 there is more resolution than is normally needed. Each motor needs a power drive unit, and that in turn is controlled by ‘clock pulses’, each pulse causing a move of 1/400th. of a revolution. A direction signal must also be given. At the lowest level of ‘automation’ these control signals can be generated by digital settings, i.e. a combination of thumbwheel settings and numeric electronic readouts. This is hardly much of an advance, as all the doping and frame-to-frame settings have to be done much the same as before.

However, there are clever gadgets called Stepper Drive Interfaces, which can act on instructions from a computer to produce all the required number and direction pulses (i.e. handle wheel movements). It should be said at this stage that the ‘camera wheel’ (no, we know you don’t still turn that by hand!) will also be driven by a stepper motor, so that it too will be controlled by the computer via its own control unit. It is possible to drive a number of motors at the same time as the camera, thereby creating the ‘go-motion’ effect of having the motors move whilst the shutter is open (think of all the creative possibilities in that!). This has been a brief explanation of the mechanical side, and having motorised we will now go back to the start, and describe the way in which the doping-out and moves can be calculated on the computer before shooting, and then used for the direct and fully automatic control of all the motors for the actual shoot.

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