Straight under the helicopter
this error
is zero and
pixel related
It increases
at the ends of the field of view. For deviations of less 5 meter over the 50 m/2 = 25 meter this gives errors of about 1-2 meter.
Max distance error 0.25 meter
If the helicopter is flown well centered on the road with high accuracy and the area is flat , the pixel resolution defines the absolute distances horizontally and it is possible to measure objects like road width within 10 cm accuracy. If the area is flat the horizontal accuracy's are very good and not so far from this value. If there are vertical deviations they give larger errors more far away from the road center but rarely they are more than 1-2 meter. The large amount of information in images gives very detailed information about the total environment around the road. Normally the largest error is the GPS which have +- 0.75 m in error
About image resolution
Camera resolution 790x560 pixels and this is displayed over about 50x40 meter on the ground . This gives a pixel foot print of 5-10 cm on the ground. This makes it possible to see small objects at 50 meter distance like hand sized objects as some thing and 30-40 cm objects as an identified object. Narrow and long objects of a few cm in thickness can be viewed if the contrast is good.
About road center definition
The total station system demands that someone from the ground shall identify the road center by the eyes. This is not so easy if the edges of the road are less well defined and sharp.
The birds eye view we have gives a far better feeling than what a ground based system can get in detecting a real and correct road center. Bumps and groves are better reduced from above as the eye easily can see the center of a rough edged road
In this case the airborne solution is very efficient and accurate.
| LaseroptronixAB |
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Telephone 46-70 714 04 70
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| Enhagsslingan 23 |
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| 187 40 Täby |
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Säte i Täby Kommun Glimmervägen 8 187 34 Täby / Sweden |
| Sweden North Europe |
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Created 2005-10-27 by Allan Jansson
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