Compute the Image Rate for Frontal Overlap on Intel® Insight Platform

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ข้อมูลผลิตภัณฑ์และเอกสารประกอบ

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11/07/2019

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
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)

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
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
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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