CGI EXPORT

CGI Export is the easier of the 2 processes (at least for the CG artist) and the major concern is to make sure that both the reference move as described above and the camera move are exported in world space, not relative to a moving parent object. This can be done in most CG packages, but it does vary. It is also important that you notify Camera Control of the units you are using just in case this needs to be accounted for. The easiest way to get the data out of a CG package is via Maya(tm) since the MEL script automatically adjusts axes and units to ensure the process is as simple as possible. If this is not possible, then if you can get the camera and reference move out into Ascii, we can import it somehow.

Accelerations & speeds

Once the move is imported into the Motion Control system, there remains the question "Can rig can actually run the move?. Mostly likely you will have some idea as to how fast the rig you are using can move as well as its range of travel, but the hardest thing to see is the acceleration needed to get the camera to move like that. Whilst a CG camera can change speed infinitely quickly, and even an abrupt change of speed is not entirely noticeable to the eye, a 1200lb Milo needs a little more time to respond. CG Systems often use cubic curves which are smooth and join smoothly, but do not necessarily meet with matching accelerations, so you can get sudden accelerations where these curves meet, and a sudden acceleration means a sudden force which means camera shake - don't blame me, it's Newton's fault. Basically, try to get the curves to be as smooth as possible and try exporting the data before the shoot and have it tested. A motion control rig also can not start instantaneously. If your move starts at speed, it is often a good idea to build on a ramp move to start and stop the camera smoothly, even if this part of the shot is not going to be used. This is not vital but can make the import process a little easier. Guide for the move

Moves imported into Flair for match moving often have a lot of jitter in them from the tracking software. This is not really perceptible in the CG system, but once you put the motion into a real camera, it becomes very shaky. In my experience this data often has to be smoothed a lot before it can run at live action speed, and for this reason, the match move data is not going to be frame perfect, but will give a very close approximation which can often be tracked in to make a perfect match. Moves programmed in CG and then exported to Flair are often delivered with the message "This is the approved move - do it exactly like this" Alas this is very often not the case, more often than not something was not modeled exactly right and so the framing won't look quite perfect and will have to be adjusted. It is better to simply sample the imported move every 12-24 frames and then adjust these few points rather than try to adjust discrete data for every frame.

Line up for Export

The line up move for exporting will really depend on what the move is all about. If there is no obvious thing to use as a line up, contact Camera Control and we can work something out. Even if it is to model an apple box in the CG package and use that as a line up. Of course, bigger is better with line up moves try to use something at least 4 feet in width. A vertical line up will not provide the rotational factor, so make sure your line up move has a significant horizontal element.

Zoom Lenses

Please do not use a zoom lens unless you really have to. They do not model well and the nodal point moves when you zoom, so it adds a whole extra complexity. If you do have to use a zoom, be prepared for a little extra work in post. Be sure to run the move without the zoom moving and run the zoom more without the rig moving if you really want to work out the zoom issues which also include not zooming on centre and other abberations

If you have any questions about Import or Exporting moves please feel free to contact Simon Wakley at Camera Control (310) 581 8343 or email simon@cameracontrol.com.