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Imaging technology |
Above: gas burner in the background of an image taken using a 55 mm focal length lens on a Digital Single Lens Reflex (DSLR) camera.
In this experiment, we used a 1,600 x 1,200 pixel Logitech Quickcam Pro for Notebooks webcam weighing 55 grams (including USB cable). See Payload I for more details on this system.
Total weight 55 grams (including USB cable).
The problem with the very small diameter lenses in most webcams is that the image degrades rapidly with movement of the camera, as can be seen above in contrast to the image from the same stationary webcam, shown below. Of course, this camera would typically be stationary, so it is excellent for its main task: less so as a camera on a moving UAV.
The 12 MPixel Canon Powershot G9, OFF in upper left, and at max optical zoom on upper right. See Payload I for more details on this camera. Total weight is 320 grams.
Above, 3m from door frame, at max wide angle setting with 35 mm focal length
Section of the above image enhanced using Auto Levels and Auto Contrast in Adobe Photoshop
Above: Now standing 5.5m from door frame, with lens at maximum wide angle setting with a focal length of 35 mm.
Below: starting with the above image, we have used Adobe Photoshop to:
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" smart sharpen" the image by removing Gaussian blur with a radius set to 2.9 pixels
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Auto Levels
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Auto Contrast
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used the " Curves" feature to accentuate the low light level features (in the shadows in the image above) at the expense of the brighter features (such as the door frame)
and we end up with the image shown next, in which we can more clearly see someone in the back of the room. The need to use a camera with a good dynamic range (ie. 14 bit pixel resolution, or better) is clear.
As above, but with lens set at maximum telephoto zoom with focal length = 210 mm.
In this experiment, we used a Nikon D40x body weighing 481 grams and a Nikon AF-S 18 - 55mm f/3.5 - 5.6 G II ED AF-S DX Zoom Nikkor lens weighing 205 grams. See Payload I for more details on this system. The camera was hand held (as opposed to being mounted on a stabilising tripod) to be more representative of a camera on a UAV.
Total weight = 686 grams.
Images taken 3 m from wall face with different zoom lens focal lengths.
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18 mm |
25 mm |
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35 mm |
45 mm |
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55 mm |
55 mm + Adobe Photoshop auto level + auto contrast |
Crop and resize
Derived from image at focal length setting = 18 mm
Derived from image at focal length setting = 55 mm
In this experiment, we used a Nikon D40x body weighing 481 grams and a Nikon AF-S VR 70 - 300mm f/4.5-5.6G IF ED Zoom Nikkor lens weighing 745 grams. See Payload I for more details on this system. The camera was hand held (as opposed to being mounted on a stabilising tripod) to be more representative of a camera on a UAV.
Total weight = 1,226 grams. The huge weight of this imaging system precludes its use on very small UAVs.
Images taken 20 m from wall face with different zoom lens focal lengths.
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70 mm |
100 mm |
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135 mm |
200 mm |
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300 mm |
300 mm + Adobe Photoshop auto level + auto contrast |
Crop and resize
Derived from image at focal length setting = 70 mm
Derived from image at focal length setting = 300 mm
© Barnard Microsystems Limited 2006 - 2008