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I have high resolution images captured by a drone using a , they are RBG and NIR images. My question is how can I calculate the reflectance for the images, the values are currently in digital numbers (DN), I do not know how to proceed. I believe I would need the information from solar radiation (using a sensor) and also from a reflective material with known refluence values, but I'm not sure.

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    What sensor are you using? Were all the images acquired at the same time period? – Aaron Jun 9 '17 at 19:50
  • Yes, the images were captured in the same time period. I use a camera sony cmos. For the NIR I use a dualband filter. – hugonbg Jun 9 '17 at 20:28
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    Seeing that the images were acquired at the same time and the sensor acquired the images at the bottom of the atmosphere, I do not see any need to convert to reflectance. – Aaron Jun 9 '17 at 20:32
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    Because you are taking the images so close to the ground, you don't have issues with pollution of the image from light coming in at other angles (scattered from aerosols or from other sources). As such you can make a fair assumption that the radiance (as represented by your DN) is the same as the reflectance of the features on the ground – Liam G Jun 13 '17 at 6:07
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    I have already answered a similar question on stackexchange (gis.stackexchange.com/questions/240357/…). The solution I propose uses an empirical line calibration method. The calibration to surface reflectance requires ground reflectance data collected through a spectral-radiometer. Alternatively, you could calibrate your UAV data to another atmospherically corrected sensor if there are pseudo-invariant features in your scene. – Osian Jun 27 '17 at 11:40

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