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Motion Blur and Automatic Light-based Speed Adjustment

Tudor -

Motion Blur (also known as Ground Smear)

As of version 1.4.0 of Map Pilot, the flight statistics panel has a item in it called "Motion Blur". The Motion Blur indicator shows how far the aircraft is traveling while the camera is exposing.

All motion that occurs while the camera is exposing will be captured by the camera's pixels. If the size of the motion is bigger than the Ground Sample Distance (GSD) of the data being collected, it will start to look like the image is smeared. Smeared imagery will lead to poor mapping results.

The motion blur indicator is generated by multiplying the exposure time by the speed. If the camera has a 1/100s exposure time (.01 seconds) and the aircraft is traveling at 10 m/s the ground smear is going to be 10 cm (.1 meters).

The coloring of the Motion Blur indicator number is grey (normal) when the value is less than the selected GSD. The number will turn yellow when the ground smear is between 1X and 2X your GSD. This indicates that there is smearing happening but it is likely within usable thresholds. The number turns red when the blur is more than 2 times your GSD. When the number is red, there will be obvious smearing in the images and it is possible they will not be usable for processing.

The general rule of thumb is to keep your ground smear to less that your GSD.

Long exposure times and high speeds will lead to large amounts of smear.

 

Automatic Light-based Speed Adjustment

Figuring out what speed to fly beforehand is nearly impossible without flying a recon flight. To make sure the best data is being collected, Map Pilot will adjust the speed appropriately to accommodate the amount of light that is available. 

An average exposure time is calculated as the aircraft travels from the point directly overhead to the beginning of the flight path. The average exposure value is used to determine how much light is available. As the start of the flight path is approached, the speed of the mission will be reduced to attempt to keep the ground smear around the GSD.

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