Stabilizing Camera Bounce with Mokey
Stabilizing Camera Bounce with Mokey
A CreativeCOW Mokey Tutorial


Stabilizing Camera Bounce with Mokey

Doug Bischoff Doug Bischoff
Ceridwen Productions
Harrisburg, Pennsylvania USA

©2004 Doug Bischoff and Creativecow.net. All rights reserved.

Article Focus:
This tutorial by Doug Bischoff describes a technique for reducing or eliminating vertical camera movement "jitter" or "bounce" using the Mokey software package from Imagineer Systems. By examining the simple techniques involved, readers will learn the basics of Mokey's powerful tracking and stabilizing features.


Download source .mov file Download Mokey project

This tutorial begins with a source QuickTime movie file of footage shot using a camera stabilizing system. As sometimes happens, a slight "bounce" is noticeable when the operator repositioned their feet. This kind of movement can be disconcerting for viewers, and so the desire here is to reduce or eliminate the bounce.

Click here to view the source QuickTime .mov file: note the slight instability in the vertical movement of the camera.



Getting Started - The first step in any Mokey work is to create a new project, either by clicking on the "new project" icon in the toolbar or by selecting "New Project..." from the File menu. Select the MokeyInput.mov source file, and check the following settings as they come up by pressing the "Next>" button:

Range to Import: First Frame: 0, Last Frame: 43

Interlaced: Frames

Frame Rate: 29.97 frames per second

Time: Frame Number

Film Type: NTSC

Camera Model: No distortion

Layers - Most Mokey operations make use of "Layers" as defined in the Layers tab. Using the Selection Tool from the toolbar, draw a square all around the entire image. You may need to use the Zoom tool to zoom out in order to see everything you're working on. In order for the Stabilizing function to work properly, your selection should include enough "headroom" on both the top and bottom of your frame to allow for the maximum camera movement. If your footage includes any panning motion, as this one does, be sure that your selection allows enough room to cover the duration of the pan: in this example note the extra "space" allowed on the right side of the footage (the middle of the footage has been compacted for brevity). Name this layer "Background."

Tracking - Since we are interested only in the movement of the entire frame (as opposed to the movement of a particular object in the frame), we need only track this one selection. The Tracker is one of the most powerful features of Mokey, and one that I will cover in more detail in future tutorials. Suffice it to say for now that using the default settings for a Background such as this will be fine for most applications: Mokey will treat the entire background as one, flat plane. This is appropriate because, in this case, that is exactly what we are interested in: the footage as a single "plane" being stable. With the background still selected (as shown), simply click "Track Forwards"

Stabilizing - Now that Mokey has calculated the movement of the background, we can instruct it to counteract that movement. This is done by simply selecting the layer we wish to track (it is already selected unless you clicked elsewhere in the work area), telling Mokey what sort of correction we wish applied, and selecting the "stabilize forward" button in the "Stabilize" pane. For our example, we want to eliminate vertical (Y axis) movement while preserving the pan in the X direction: de-select "X Translation." If there was some rolling movement present in the shot as well, we could attempt to correct this with "rotation" stabilization as well.

Here is where the true power of Mokey becomes apparent. If you wish to dampen rather than completely eliminate the motion, de-selecting "Maximum" in the Smoothing Level pane and setting a level in the box below will give you control over how much movement Mokey eliminates. Finally, in the "Borders" pane, the "Auto Fill" check box is the hidden gem. With this selected, Mokey will use data from other frames to re-construct the missing pixels after applying the stabilization. No more repeated-pixel borders or zoomed-in effects! Note in this finished clip how the woman's hair and the chainmail on the man's arm have been restored seamlessly!

Click here to see Mokey Stabilized movie

If you find that there is some artifacting or color shifts in the reconstructed areas, try selecting "Model Illumination" (for color and brightness shifts) or "Dissolve" (for detal artifacting) and re-applying the stabilization.

Conclusion - All that remains is to save the results out of Mokey for use elsewhere. There is one slight "gotcha" to be aware of, and that is the "RGB Channels" pop-up. If you leave it at the default of "Original" then you will simply save to disk your original clip! To be sure that you have what you want saved, ensure that this pop-up is set to "Stabilized." I recommend using "Image Sequence" Exporting for later re-assembly in QuickTime Pro or other application.

I hope this gives you a taste of the power of Mokey and remember, we've just scratched the surface!

For questions or other feedback, please visit the Cow's mokey forum.

-Doug Bischoff




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