Compute the Image Rate for Frontal Overlap on Intel® Insight Platform
The image shooting rate to achieve a given frontal overlap depends on:
- The speed of the UAV/plane
- The GSD and the pixel resolution of the camera
The image below is of a camera range overlap according to in flight position.
Figure 1.
D = distance covered on the ground by one image in the flight direction [m]
overlap = percentage of desired frontal overlap between two images
od = overlap between two images in the flight direction [m]
x = distance between two camera positions in the flight direction [m]
v = flight speed [m/s]
t = elapsed time between two images (image rate) [s]
From Figure 1, we obtain the following equations:
od = overlap * D (1)
x = D - od (2)
t = x / v (3)
x = D - od (2)
t = x / v (3)
Two cases are possible camera orientations:
Click or the topic for details:
Camera oriented with the sensor width (long dimension) perpendicular to the flight direction (usual case)
Figure 2. Sensor width placed perpendicular to the flight direction.
D = Dh = (imH * GSD) / 100 (4)
Where:
GSD = desired GSD [cm/pixel]
imH = image height [pixel]
Dh = distance covered on the ground by one image in the height direction (footprint height) [m]
Combining Equations (1) and (4) into Equation (2):
x = Dh - overlap * Dh
x = Dh * (1 - overlap)
x = ((imH* GSD) / 100) * (1 - overlap) (5)
| Note | x is given in [m], considering that the GSD is in [cm/pixel]. |
Combining the equations (3) and (5):
t = x / v = ((imH * GSD) / 100) * (1 - overlap) / v (6)
Example: In order to achieve an overlap of 75% (overlap = 0.75) and a GSD of 5 [cm/pixel], supposing that the image height is 4000 [pixels] and the speed of the UAV/plane is 30 [km/h] = 8.33 [m/s], based on the equation (6), the image rate should be 6 seconds:
t = ((imH * GSD) / 100) * (1 - overlap) / v = ((4000 * 5 ) / 100) * (1 - 0.75) / 8.33 = 6 [s]
Camera oriented with the sensor width (long dimension) parallel to the flight direction
If the camera is placed on the plane / UAV having the sensor width (long dimension) parallel to the flight direction:
Figure 3. Sensor width placed parallel to the flight direction.
D = DW = (imW * GSD) / 100 (7)
Where:
DW = distance covered on the ground by one image in the width direction (footprint width) [m]
imW = image width [pixel]
GSD = desired GSD [cm/pixel]
Combining equations (1) and (7) into the equation (2):
x = DW - overlap * DW
x = DW * (1 - overlap)
x = ((imW * GSD) / 100) * (1 - overlap) (8)
| Note | The result is given in [m], considering that the GSD is in [cm/pixel]. |
Combining equations (3) and (8):
t = x / v = ((imW * GSD) / 100) * (1 - overlap) / v (9)
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