Synthèse
Calibrates the digital number (DN) values of imagery from some satellite sensors. The calibration uses sun elevation, acquisition date, sensor gain, and bias for each band to derive Top of Atmosphere reflectance, plus sun angle correction.
For most sensors, the values used for this function will be found in the image metadata file.
Discussion
For more information on how this function works, see the Apparent Reflectance raster function.
The referenced raster dataset for the raster object is temporary. To make it permanent, you can call the raster object's save method.
Syntaxe
ApparentReflectance (raster, {radiance_gain_values}, {radiance_bias_values}, {reflectance_gain_values}, {reflectance_bias_values}, {sun_elevation}, {albedo}, {scale_factor}, {offset})
Paramètre | Explication | Type de données |
raster | The input raster. | Raster |
radiance_gain_values [radiance_gain_values,...] | The list of radiance gain values, in order of bands. (La valeur par défaut est None) | Double |
radiance_bias_values [radiance_bias_values,...] | The list of radiance bias values. (La valeur par défaut est None) | Double |
reflectance_gain_values [reflectance_gain_values,...] | The list of reflectance gain values. (La valeur par défaut est None) | Double |
reflectance_bias_values [reflectance_bias_values,...] | The list of reflectance bias values. (La valeur par défaut est None) | Double |
sun_elevation | The sun elevation angle, in degrees. (La valeur par défaut est None) | Double |
albedo | Specifies whether to provide the apparent reflectance values as albedo, which is the fractional value of the available energy that is reflected by the planetary surface. It is expressed as a dimensionless floating-point number between 0 and 1.
(La valeur par défaut est False) | Boolean |
scale_factor | The multiplier for the albedo to convert all floating-point values into integer values. (La valeur par défaut est None) | Integer |
offset | The offset for the scaled albedo value.
(La valeur par défaut est None) | Integer |
Type de données | Explication |
Raster | The output raster. |
Exemple de code
Calibrates a Landsat scene to apparent reflectance.
# Import system modulesimport arcpy
import arcpy
from arcpy.ia import *
# Set the local variables
in_raster = "C:/data/Landsat.tif"
radiance_gain_values = [0.762824, 1.442510, 1.039880]
radiance_bias_values = [-1.52, -2.84, -1.17]
reflectance_gain_values = None
reflectance_bias_values = None
sun_elevation = 51.71
albedo = False
scale_factor = 255
offset = None
# Apply ApparentReflectance function
reflectance_raster = arcpy.ia.ApparentReflectance(in_raster, radiance_gain_values,
radiance_bias_values, reflectance_gain_values, reflectance_bias_values,
sun_elevation, albedo, scale_factor, offset)
# Save the output
reflectance_raster.save("C:/arcpyExamples/outputs/Landsat8_reflectance.crf")
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