FPAR

Description

Calculates the fraction of absorbed photosynthetically active radiation.

Parameters

fpar(file, filo, dbic, dboc, fparm)

Name	Type	Caption	Length	Value range
FILE *	str	Input file name	1 -
FILO	str	Output file name	0 -
DBIC *	List[int]	Input raster channels	2 - 2
DBOC	List[int]	Output FPAR channel	0 - 1
FPARM	List[float]	FPAR parameters (a,b,c)	0 - 3	10.0 Default: 1.0,0.4,1.0

* Required parameter

Parameter descriptions

FILE

Specifies the name of the input file that contains the satellite image channels.

FILO

Specifies the name of the output file to receive the FPAR image. The output file can be the same as the input file.

DBIC

Specifies the two input image channels that contain, respectively, the atmospherically corrected red and NIR sensor band reflectance images generated by the ATCOR function.

DBOC

Specifies the output channel to receive the FPAR image.

If the specified output file is to be created, this parameter defaults to channel 1 in the output file.

FPARM

Specifies three parameters for the FPARM calculation using the following equation:

FPARM = c*[1-a*exp(-b*LAI)] 

The maximum value for any of the three parameters is 10.0.

Details

FPAR calculates the fraction of absorbed photosynthetically active radiation (FPARM) image stored in the specified output file.

To run FPAR, you must enter atmospherically corrected red and NIR sensor bands channels (generated using ATCOR).

FPAR uses the following equation to perform the calculation:

FPAR = c*[1-a*exp(-b*LAI)]

where a, b, and c represent the FPARM parameters.

Example

Use the atmospherically corrected reflectance image corr_essen.pix (Landsat-5 TM) produced by ATCOR to compute FPAR:

from pci.fpar import fpar

file	=	'corr_essen.pix'	# input file
filo	=	'fpar_essen.pix'	# output file
dbic	=	[3,4]	# input Red and NIR channels
dboc	=	[1]	# output channels
fparm	=	[1.0,0.4,1.0]	# FPAR parameters

fpar( file, filo, dbic, dboc, fparm )
        

The result is an FPAR image stored in fpar_essen.pix.

References

The Atmospheric Correction component was produced by PCI Geomatics using algorithms developed by DLR, German Aerospace Research Establishment. The algorithms used in the various programs of the component are based on information from the following papers:

Lanzl, F. and R. Richter. "A Fast Atmospheric Correction Algorithm for Small Swath Angle Satellite Sensors". ICO topical meeting on atmospheric, volume, and surface scattering and propagation, Florence, Italy, August 1991.

Richter, R. "Error Bounds of a Fast Atmospheric Correction Algorithm for the Landsat Thematic Mapper and Multispectral Scanner Bands", Applied Optics, 30, no.30 (1991):4412-4417.

Richter, R. "Model SENSAT: A Tool for Evaluating the System Performance of Optical Sensors", SPIE PROPAGATION ENGINEERING 1312 (1990): 286-297.

Ahern, F.J., P.M. Teillet, and D.G. Goodenough. "Transformation of Atmospheric and Solar Illumination Conditions on the CCRS Image Analysis System". Paper presented at Machine Processing of Remotely Sensed Data Symposium, 1977.

Richter, R. "A Fast Atmospheric Correction Algorithm Applied To Landsat TM Images", Int. J. Remote Sensing, 11, no. 1 (1990): 159-166.

Calculation of FPAR: Wiegand, C.L. et al., Remote Sensing Environment, 33 (1990): 1-16.

Calculation of LAI from vegetation index (SAVI): Choudhury et al., Remote Sensing Environment, 50 (1994): 1-17.