Shootout: 4K vs PTZ CamerasBy Ethan Ace, Published Feb 19, 2015, 12:00am EST
The question is: how does this increase in resolution compare to the optical zoom of HD or even SD PTZs?
We tested these cameras day and night in an outdoor parking lot, to ~500' range. Light levels at night varied from about 0.3-0.5 lux, from building and ambient lights.
This image shows the overall scene from a wide FOV taken from a 4K camera. The angle of view in this image is ~70°.
Cameras were tested side by side, with the fixed cameras maintaining the same angle of view regardless of distance to target, while the PTZ cameras were optically zoomed in to a 15-16' field of view at each point (30', 100', 250', and 500'). At 500', both 1080p PTZ models' field of view was slightly wider, as we reached their maximum telephoto zoom range, while the SD PTZ was narrower and able to maintain the same field of view width.
Axis, Bosch, Canon and FLIR Cameras Tested
To find out, we tested three PTZs (from Axis, FLIR and Canon) against three multi-megapixel (Axis 4K, Bosch 4K and Bosch 5MP) cameras in our outdoor test scene at ranges up to 500', day and night.
Here are our key findings from this test:
- At short range, fixed 4K and 5MP cameras using a wider field of view provide similar details to 1080p PTZs zoomed into the subject in a narrower FOV. The SD PTZ provides fewer details at this range.
- At medium to long range, PTZ cameras, including the SD model, provide much better details of our test subject and chart compared to fixed 4K cameras.
- Due to its narrow telephoto FOV, the VGA PTZ provided better details of our subject at 500' than the 1080p non-IR PTZ, though moderately worse than the IR PTZ.
- At close range (~30'), the 4K and 5MP cameras outperform all but the integrated IR PTZ, with better details of our test chart and subject.
- Beyond this (100'+), the integrated IR PTZ easily outperforms all other cameras tested, with details of the subject at over 250', and detection over 500'.
- The SD PTZ outperformed the 1080p non-IR PTZ model at medium ranges (100-250'), providing detection of the subject where the 1080p model provided no usable images.
An operator controlled PTZ can still provide better range and detail than even 4K fixed cameras can provide, despite the jump in resolution and processing over past generation cameras. For live monitored installations which require the utmost detail, even a standard definition PTZ provides better details at all but very close ranges than 4K cameras. PTZ cameras' advantages are further increased with the introduction of integrated IR PTZs, which provide detection and some details at long range in low light, a previous weakness of PTZs.
However, if the system will not be operated live, fixed cameras should be used. Putting PTZ cameras on tour introduces the possibility that they will be aimed in the wrong direction during an incident, missing key events, and leaving them stationary negates their optical zoom benefits.
Angle of View Differences
To give a sense of just how much angle of view differs between the fixed multimegapixel and PTZ cameras tested here, see the image below. The wider of the two angles shown is the fixed cameras' field of view, ~70°. By contrast, the yellow represents the PTZs' angle of view at their longest focal length, ~2°.
Because of this huge difference in AoV, as seen in the comparisons below, with their wider field of view, the fixed MMP cameras deliver fewer details, but more overview information of the scene than a zoomed PTZ provides. The PTZs provide much better details when zoomed at longer ranges, but completely lose overview information when zoomed to their telephoto limits.
Beginning at close range (~30' from cameras), PPF is high in both the 4K, 5MP, and HD PTZ models, with solid details of the subject and chart. At this range even the SD Canon PTZ provides over 45 PPF and some details of our subject.
Note that the Axis P1428-E is moderately blurry in this scene, even after manual and auto focusing, which was noted in our indoor tests of this camera, as well.
Moving to 100' from the cameras, there is a drastic drop in detail in the fixed cameras, as PPF drops below 30 in the 4K models, and below 20 in the 5MP. PPF stays constant in the PTZ cameras as field of view width remains approximately the same as the cameras optically zoom.
At 250', no details are available in any of the fixed cameras, as PPF is simply too low. Again, details of the PTZs are similar. There is some slight loss in detail due to the long lenses used (as we found in our previous tests), but PPF is still extremely high.
Finally, at ~500' from the cameras, PPF on the 1080p PTZs drops as we reach their maximum optical zoom level. The Canon VGA PTZ, however, maintains 45 PPF, providing details similar to shorter ranges.
At night, performance of the fixed multimegapixel models drops significantly. Some details and the first 2-3 lines of the chart are available, but the scene is simply too dark to provide recognition.
The FLIR PTZ provides the best images in this scene due to its built in IR. The Canon VGA model outperforms the Axis 1080p PTZ due to its better low light performance, despite the more than 50% drop in PPF.
As in the daytime, details drop sharply in the fixed cameras, and the FLIR PTZ provides the best details in this scene. The Canon PTZ still provides detection of the subject and chart, but the Axis model is nearly black, providing no usable images.
Finally, at 500', only the FLIR PTZ is able to provide usable images at all, with other cameras either too dark, too low PPF, or both.
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