mapAsas 1 "April 1996"


mapAsas - an image based (HIPS) routine for mapping BRDF model parameters listed in a 'control' file through to a classified HIPS image (e.g. ASAS to TM), classified using something like miniDist(1).


[-i input image][-o output image][-v verbose][-c control file][-b mmap block size]

DESCRIPTION mapAsas is a utility designed to allow BRDF model parameters produced by inverting ASAS multi-angle reflectance data against a suite of BRDF kernels (using walthall), to be mapped through to a classified reflectance image.

If ASAS data are available for a particular area, model inversions can be performed using walthall, which yields images containing the BRDF model parameter information for each pixel. If a TM scene of the same area is available, this can be classified using the spectral information available in each pixel of the ASAS images of the same region (see miniDist(1)). If every pixel of the ASAS images are assigned a separate class, then the model parameters produced by walthall can be directly related to these classes. A control file can be constructed (see getModelParams) with each class containing the model parameter information for a single pixel in the ASAS images. These parameters are then mapped through to the corresponding classes in the TM scene.


-i specifies the input image name.
-o specifies the output image name.
-v specifies verbose mode, giving details of memory mapping etc.
-b specifies the block size used for memory mapping. Try 1000 for starters. Note that the environment variables MMAP_IP and MMAP_OP must be set to 1 for the input and output images to be memory mapped. These can be set on the comand line by typing "set MMAP_IP = 1" and "set MMAP_OP = 1" respectively.
-c specifies the name of the control file containing model parameters, where the format is as follows:

# comment, or information about file
CLASS 0 X X X X # class name
CLASS 1 X X X X # class name
CLASS 2 X X X X # class name
CLASS 3 X X X X # class name
CLASS 4 X X X X # class name . . . . . . . . . . . . . . . . . .

The initial comment line is ignored, and is for the users information only, as are the comments or names following each class. The X's obvioulsy represent the DN value for each class, in each band (4 bands in this case). A null class (CLASS 0) can also be used. Checks are made to ensure that the number of bands specified is the same on each line, and also that the number of separate classes actually present in the image is not greater than the number listed in the control file.


miniDist(1), walthall(1)


(C) University College London, Gower Street, London WC1E 6BT


Mathias Disney, 1996
Remote Sensing Unit
Department of Geography, UCL

Back home..Take me home..