ReadMe.Txt for Sigma0, Version 1.1

NOTE: THE JET PROPULSION LABORATORY PROVIDES THIS SOFTWARE "AS IS"
AND MAKES NO GUARANTEE AS TO ITS FITNESS FOR ANY PARTICULAR PURPOSE.
THIS SOFTWARE IS A BETA VERSION AND CONTAINS SOFTWARE BUGS.

May 1, 1997

This README file contains installation instructions for 

	Sigma0 for the PC, version 1.1

This program requires Microsoft Windows 3.1 or later.

Sigma0 will read images in compressed stokes format (*.STK) and
display them in the MS-Windows environment.

To install Sigma0 for the PC follow these steps:

1) Unzip the file SIGMA0PC.ZIP. You should have the following files:

	README.TXT		- The file you are reading.
	BC450RTL.DLL		- Library file
	XWMBA420.DLL		- Library file
	XWMHN420.DLL		- Library file
	XWMTE420.DLL		- Library file

2) Copy the *.DLL files into the C:/WINDOWS directory on your hard disk.

3) Copy the SIGMA0PC.EXE from the SIRCED03 CD-ROM into a subdirectory 
   such as C:/SIGMA0.

4) Reboot your machine.

Sigma0 is now installed. Start MS-Windows 3.1 and execute the SIGMA0 
program from the Program Manager via menu items "File | Run". The 
executable is located in the subdirectory C:/SIGMA0/SIGMA0PC.EXE.

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May 1, 1997 - Sigma0 v1.1 - Changes from verion 1.0C

Since 1995, all JPL AIRSAR data has been processed using the new Integrated
Processor (IP).  The Integrated Processor differs from the old processor in
that it processes the entire range of data (as opposed to half the range),
has motion compensation, and handles TOPSAR data.  The header at the top of
an IP data product contains some differences from the header generated by
the old processor.  Also in IP data the incidence angle is a function of
sample position rather than line position.

Sigma0 v1.1 now contains the capability to read in AIRSAR data processed by
the Integrated Processor.  The program scans for the processor version
number in the header.  A processor version greater than or equal to 5.0.1
shows that the data has been processed using the Integrated Processor.
Sigma0 then extracts header information and calculates the incidence angle
accordingly.  This activity is transparent to the user.

For more detailed information about the Integrated Processor, check out the
AIRSAR site on the world wide web at http://airsar.jpl.nasa.gov.  Follow
the Technical Information link and select the TOPSAR link under Data
Formats.

1.  Selecting the Full Zoom feature on a large image will cause the system
to hang.  Also, because the Display Sigma0's feature does not display the
pixel values well on the PC, the Full Zoom feature has been disabled in
this version.  (Full Zoom is a feature that will zoom into the image the
proper number of times so that sigma0 values can be written on top of each
pixel.)

2.  When working with large images, repeatedly using the Zoom In feature
will ultimately cause the system to hang.  Therefore a limit of 10
"zoom-ins" for images larger than 1024 x 1024 has been added.  Also,
another limit has been added to prevent a rollover condition in the code
that occurs when working with large images.  If this limit is reached, it
will affect the number of times you can zoom into the image.