Zusammenfassung
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.
Auswertung
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.
Syntax
ApparentReflectance (raster, {radiance_gain_values}, {radiance_bias_values}, {reflectance_gain_values}, {reflectance_bias_values}, {sun_elevation}, {albedo}, {scale_factor}, {offset})
Parameter | Erklärung | Datentyp |
raster | The input raster. | Raster |
radiance_gain_values [radiance_gain_values,...] | The list of radiance gain values, in order of bands. (Der Standardwert ist None) | Double |
radiance_bias_values [radiance_bias_values,...] | The list of radiance bias values. (Der Standardwert ist None) | Double |
reflectance_gain_values [reflectance_gain_values,...] | The list of reflectance gain values. (Der Standardwert ist None) | Double |
reflectance_bias_values [reflectance_bias_values,...] | The list of reflectance bias values. (Der Standardwert ist None) | Double |
sun_elevation | The sun elevation angle, in degrees. (Der Standardwert ist 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.
(Der Standardwert ist False) | Boolean |
scale_factor | The multiplier for the albedo to convert all floating-point values into integer values. (Der Standardwert ist None) | Integer |
offset | The offset for the scaled albedo value.
(Der Standardwert ist None) | Integer |
Datentyp | Erklärung |
Raster | The output raster. |
Codebeispiel
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")