Re: Motion Control Camera

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "aneurysm99" <netboy3@h...>
wrote:

> I originally posted this at the O'Reilly forum for Make magazine,

and

> was told to come here for comments and suggestions:
>
> DIY motion control camera!
>
> I loved the steadycam project in the first issue, but I can't help

but

> wonder if there is also a DIY solution for something like a montion
> control camera. The basic idea of the motion control camera is
> shooting the exact same pass multiple times and then overlaying the
> passes to create various effects (ie. the multiple Kylie Minogues in
> the "Come into my World" video or the band members of System of a

Down

> intesecting each other in the "Chop Suey" video).
>
> Generally these things are attached to huge crane rigs and have some
> type of computer control, but I'm thinking of something that would

be

> more on the scale of a table top model for a stop-motion project.
>
> Is this DIY feasible? If so, write it up for a future issue. I want

to

> build it!
>
> ***
>
> Any suggestions or advice on making this camera would be greatly
> appreciated.

It's certainly feasible.

With the small cameras available it wouldn't require large motors
either, a couple of the HobbyCNC 3 axis unipolar kits with the 127 or
200 oz motors would be sufficient.

You didn't specify what type of camera you wanted to use, but you
could readily use a consumer digital camera, 35mm camera or video
camera. All are available in small sizes, fairly inexpensive and
easily modified for remote trigger.

You'd need want an add on parallel port card for the controll PC to
give you two ports for the two stepper drives and enough extra I/O
for camera trigger and any other stuff you might want.

This application is actually a bit easier mechanically than most of
the mills, lathes and routers on this forum. Since you are
positioning a camera you do not have any cutting forces to contend
with so absolute rigidity is not as critical. If you're doing a stop
motion type of operation you don't have to worry about perfectly
smooth motion either.

The only tricky parts would be the mechanics for a pan/tilt/roll head
to hold the camera, and some software to assist in generating the G-
code for the desired motion path.

Common CNC control software such as EMC or Mach3 can readily handle 6
axis movemet, giving you the X, Y, Z and pan (A), tilt (B) and roll
(C) for the camera.

The CNC control software is not really intended for a stop motion
type of application and you wouldn't use 99% of it's capabilities,
but it certainly is quite capable of performing the moves.

If you can come up with software to generate the position coordinates
for each desired frame position, translating those coordinates into G-
code that the CNC software can interpert would be simple.

For each frame position you'd generate several lines of G-code: A
move to the coordinates, a brief pause to allow any vibration of the
machine to stop, a trigger signal for the camera and then one more
pause if needed before the next move.

You could have custom software to do the control of the machine
instead of the CNC software, but for the low - no cost of the CNC
software it's probably not worth the effort.

The CNC software also gives the potential for real time moves, not
just stop motion, as long as the physical machine is smooth enough
since the CNC software is designed to provide smooth interpolation of
the moves in all axes.

Pete C.