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What is different between Reflectance and Radiance?


ahmad125

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from above article, I quote for you :

 

 

Digital Number (DN)

 
The generic term for pixel values is Digital Number or DN. It is commonly used to describe pixel values that have not yet been calibrated into physically meaningful units. 
 
Radiance
 
Radiance is the amount of radiation coming from an area. To derive a radiance image from an uncalibrated image, a gain and offset must be applied to the pixel values.  These gain and offset values are typically retrieved from the image's metadata or received from the data provider. 
 
Reflectance
 
Reflectance is the proportion of the radiation striking a surface to the radiation reflected off of it.  Some materials can be identified by their reflectance spectra, so it is common to correct an image to reflectance as a first step toward locating or identifying features in an image.
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in a short explanation

 

you would use radiance if you only doing landuse landcover classification using hard classification (i.e nearest neighbour, paralelepiped, maximum likelihood classification) 

 

you would use reflectance if you want to extract some biophysical data from imagery spectral information (i.e vegetation water content, fPAI, percentage vegetation cover, soil moisture etc), or Landuse/landcover soft classification (i.e spectral unmixing, spectral angle mapper, artificial neural network, etc)

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in a short explanation

 

you would use radiance if you only doing landuse landcover classification using hard classification (i.e nearest neighbour, paralelepiped, maximum likelihood classification) 

 

you would use reflectance if you want to extract some biophysical data from imagery spectral information (i.e vegetation water content, fPAI, percentage vegetation cover, soil moisture etc), or Landuse/landcover soft classification (i.e spectral unmixing, spectral angle mapper, artificial neural network, etc)

Thanks

Do you have the resources to introduce?

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