LAI

Description

Calculates a leaf area index model value.

Parameters

lai(file, filo, dbic, dboc, lpar)

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 LAI model channel	0 - 1
LPAR	List[float]	LAI parameters (a0, a1, a2)	0 - 3	Default: 0.82,0.78,0.60

* Required parameter

Parameter descriptions

FILE

Specifies the name of the PCIDSK file from which image data is read.

FILO

Specifies the name of the PCIDSK file to receive the output LAI images.

If this parameter is not specified, the input file (FILI) is used for output.

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 output channel to receive the output LAI image.

LPAR

Optionally specifies three parameters for the LAI calculation using the following equation:

SAVI = a0-a1*exp(-a2*LAI)    

Details

LAI calculates the leaf area index model value. To run LAI, you must enter atmospherically corrected RED and NIR sensor band channels generated by ATCOR.

LAI is calculated using the following equation:

SAVI = a0-a1*exp(-a2*LAI)

where a0,a1,a2 specify the three parameters.

Example

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

from pci.lai import lai

file	=	'corr_essen.pix'	# input file
filo	=	'lai_essen.pix'	# output file
dbic	=	[3,4]	# input Red and NIR channels
dboc	=	[1]	# output channel
lpar	=	[0.75,0.65,0.6]	# LAI parameters

lai( file, filo, dbic, dboc, lpar )

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.

Choudhury, B.J., Ahmed, N.U., Idso, S.B., Reginato, R.J., Daughtry, C.S.T., 1994. "Relations between evaporation coefficients and vegetation indices studied by model simulations", Remote Sensing Environment, 50(1), 1-17.