Camera Vibration / Stabilizer Solutions

Shaky images can severely undermine image quality, strain operator eyesight and make monitoring more difficult. What can be done about the problem? In this note, we explain the issues and examine what to do:

• Harmonics / Vibrations
• Differences between Dynamic and Fixed Vibrations
• 3rd Party Devices
• Integrated Electronic Image Stabilization
• Dampening Mounts

Background

Keeping cameras steady can be a real challenge. Cameras mounted outside are often subject to wind or shaky mounts, and units mounted indoors can be prone to vibrations from air handler vents or from machinery. In the clip below, the a stabilizing device manufacturer shows a 'before' and 'after' example that demonstrates just how disruptive vibrations can be and limitations on what stabilization can do:

A discussion question posed the question of what options are available to combat this issue? We take a look at the root cause of the problem and the different solutions available for dealing with it.

Harmonics

Fundamentally, vibrations are waves of pressure. The rapidity, consistency, and strength of vibrations can be measured by frequency and amplitude.  Resolving intermittent, dynamic, and very strong vibrations, as in the case of wind sway, are difficult to correct while repeatable, constant, less intense vibrations, like cyclic machine vibrations are more easily resolved.

The frequency, or how rapidly vibrations occur, play a key role in how they are addressed. For example, low frequency movements like rolling waves can be corrected by mechanical, motion cancelling mounts. However, mechanical mounts are unsuited to cancel high frequency movements, because they often cannot register and respond quickly enough to be effective.

For surveillance cameras, dynamic vibrations are more difficult to correct. The more predictable movement becomes, the simpler it is to adjust images to compensate. Many tough vibration issues require more than a single 'remedy' and the best results come from 'stacking' solutions to minimize the impacts. Often, the best solution comes from a mix of software mitigation, mounting solutions, and camera placement.

Three Methods

The techniques in dealing with camera vibrations take three basic forms:

• Dampening Mounts
• 3rd Party Devices
• Integrated Electronic Image Stabilization

Each method comes with its own advantages and disadvantages in dealing with the issues. We examine each in detail below: 

Dampening Mounts/Hardware

Hardware solutions that dampen vibrations range from inexpensive vibration dampeners costing a few dollars to gyroscopically stabilized positioners costing thousands of dollars that mechanically compensate for movement. If vibration amplitudes are small (weak), then the addition of common rubber or neoprene bushings at the mount can absorb vibrations, especially those arising from ambient machinery or air handler units. The image below shows an assortment of bushing dampeners than can be adapted for use on camera mounts:

The ultimate effectiveness of dampening hardware depends on how it is used. Hardware installed between the camera and the mount is usually the least expensive to install, however hardware between housing and the mounting surface, while more expensive, generally offers a better result.

In tougher cases, where vibrations or sway is dynamic and has powerful amplitude (eg: ocean waves, driving winds, high tower mounts), mounts featuring internal gyroscopes or floating bases that maintain the camera in a level position regardless of external deflection, can be used. While these units are suited to deal with a wide range of vibration, they are costly and may not be sensitive enough to adjust for high frequency vibrations. 

Pros

• Mechanical Dampeners can mitigate the widest range of vibration sources.
• Dampening Bushings are inexpensive and commonly available supply items.

Cons

• Adding dampeners to mounts can complicate install, and 'surveillance mount' specific kits are not common.
• Heavy-duty Gyroscopic stabilizers cost thousands of dollars, and may require separate controllers.

3rd Party Devices

This stabilization option takes place externally of the camera and mount, and is connected midspan between the camera and recorder. The device mitigates camera shake by post-processing video streams.

While several different appliances are available, the high cost of the solutions (~$5000 per channel) restricts their adoption in many cases.

Pros 

• 3rd Party Appliances not limited to certain frequencies or vibration intensities.
• Other 'image enhancement features' may be provided in appliance

Cons

• Expensive, often costing more per channel than several cameras
• Limited resolution often (analog / SD)

Integrated Electronic Image Stabilization

Image stabilization processing taking place within the camera itself is often noted as "electronic image stabilization", or simply "EIS" on spec sheets. While implementations of EIS vary among manufacturers, they frequently deliver modest results. These features typically have the best results normalizing low-intensity, high-frequency, fixed vibrations, and have mixed effectiveness where movement is more intense and less patterned. 

The manufacturer's promotional image illustrates the effect of an integrated EIS feature:

Pros

• Unlike 3rd Party Appliance, EIS is built in
• EIS does not add significant cost compared to other stabilization options.

Cons

• Modest impact, and not effective in correcting vibrations with wide amplitude.
• May result in resolution reduction at edges of frame 
• Only available on a minority of cameras

Recommendations

Figuring out the right anti-vibration solution to use can be tricky. Consider these guidelines:

• For slight, high frequency vibrations like machinery or air handling units, using cameras with integrated EIS or applying vibration dampening hardware offers the least expensive solution.
• For high-intensity, low-frequency, and dynamic vibrations, mounting hardware like gyroscopic mounts offer the best solution.
• When cameras that do not support EIS are in use, a 3rd Party Appliance may be considered. However, due to high cost this is usually the last option chosen among the available options.

Not all vibrations follow a single pattern, and the above options may be layered atop each other for the best result.