================================================================================
ISCE Python3 Version
================================================================================

This is the Interferometric synthetic aperture radar Scientific Computing
Environment (ISCE).  Its initial development was funded by NASA's Earth Science
Technology Office (ESTO) under the Advanced Information Systems Technology
(AIST) 2008 and is currently being funded under the NASA-ISRO SAR (NISAR)
project.

THIS IS RESEARCH CODE PROVIDED TO YOU "AS IS" WITH NO WARRANTIES OF CORRECTNESS.
USE AT YOUR OWN RISK.

Use of this software is controlled by a non-commercial use license agreement
provided by the California Institute of Technology Jet Propulsion Laboratory.
You must obtain a license in order to use this software.  Please consult the
LICENSE file found in this package.

ISCE is a framework designed for the purpose of processing Interferometric
Synthetic Aperture Radar (InSAR) data.  The framework aspects of it have been
designed as a general software development framework.  It may have additional
utility in a general sense for building other types of software packages.  In
its InSAR aspect ISCE supports data from many space-borne satellites and we
continue to increase the number of sensors supported.  At this time the sensors
that are supported are the following: ALOS, COSMO_SKYMED, ENVISAT, ERS,
KOMPSAT5, RADARSAT1, RADARSAT2, and  TERRASARX.

Starting with svn revision number r1349 (2014-03-28) ISCE was converted to work
with Python3.  From that point forward major development has been limited to
that version.  Some bug fixes and new code developed in the Python3 version were
merged into the Python2 version to support our Python2 users, but going forward
we highly recommend that our users convert to using the Python3 version.  We
plan to release a "final" Python2 version of the code very soon.

================================================================================
Contents
================================================================================

1.  Software Dependencies
1.1 Note On 'python3' Exectuable Convention
1.2 Installing dependencies with provided setup script
1.3 Hints for installing dependencies by hand.
2.  Building ISCE
2.1 Configuration control: SCONS_CONFIG_DIR and SConfigISCE
2.2 Install ISCE
2.3 Setup Your Environment
3.  Running ISCE
3.1 Running ISCE from the command line
3.2 Running ISCE in the Python interpreter
3.3 Running ISCE with steps
3.4 NOTE on DEM
4.  Input Files
5.  Component Configurability
5.1 Component Names: Family and Instance
5.2 Component Configuration Files: Locations, Names, Priorities
5.3 Component Configuration Help

================================================================================
1. Software Dependencies
================================================================================

gcc >= 4.3.5
fftw 3.2.2
Python >= 3.2  (3.3 preferred)
scons >= 2.0.1
for RadarSAT2 - gdal python bindings >= 1.9
for COSMO-SkyMed -  hdf5 >= 1.8.5 and h5py >= 1.3.1
for RadarSAT1 - spiceypy

The easiest way to install most of these is with package managers such as
'apt-get' on Linux systems or 'macports' on MacOsX.  To use these, however, may
require that you have superuser capabilities on your computer.  If that is not
possible, then we provide a setup script described in Section 1.2 that will
allow you to do a "user" installation of the dependencies, setup your
environment variables, and install ISCE for you.

================================================================================
1.1 Note On 'python3' Exectuable Convention
================================================================================

We follow the convention of most package managers in using the executable
'python3' for Python3.x and 'python' for Python2.x.  This makes it easy to turn
Python code into executable commands that know which version of Python they
should invoke by naming the appropriate version at the top of the executbale
file (as in #!/usr/bin/env python3 or #!/usr/bin/env python).  Unfortunately,
not all package managers (such as macports) follow this convention.  Therefore,
if you use one of a package manager that does not create the 'python3'
executable automatically, then you should place a soft link on your path to
have the command 'python3' on your path.  Then you will be able to execute an
ISCE application such as 'insarApp.py as "> insarApp.py" rather than as
"> /path-to-Python3/python insarApp.py".

--------------------------------------------------------------------------------
1.2 Installing dependencies with provided setup script
--------------------------------------------------------------------------------

This distribution includes a script that is designed to download build and
install all relevant packages needed for ISCE (except for h5py, which presently
must be built by hand but is only needed for Cosmo-Skymed, spiceypy, only
needed for RadarSAT1, and gdal python bindings).  The script is in the setup
directory, and is called setup.py.  To run it, you should cd to the setup
directory, then issue the command

> install.sh -h

to see instructions on how to run the script.  The minimal command option is
simply,

> install.sh -p <INSTALL_PATH>

where <INSTALL_PATH> is a path where you have permission to create files.  This
will check whether the dependencies exist on your default paths and then install
those that do not on the specified path.

The path should be in a local directory away from the system areas to avoid
conflicts and so that administrator privileges are not needed. The config.py
file contains a list of urls where the packages are currently downloaded from
Commenting out a particular package will prevent installation of that package.
If the specified server for a particular package in this file is not available,
then you can simply browse the web for a different server for this package and
replace it in the config.py file. Below under the "Building ISCE" section,
there are instructions on how to point to these packages for building ISCE.

Once all these packages are built, you must setup your PATH and LD_LIBRARY_PATH
variables in the unix shell to ensure that these packages are used for compiling
and linking rather than the default system packages.

--------------------------------------------------------------------------------
1.3 Hints for installing dependencies by hand.
--------------------------------------------------------------------------------

If you would prefer to install all these packages by hand, follow this procedure:

Compile the following

for Radarsat2, Sentinel1A and Tandem-X gdal with python bindings >= 1.9

Building gcc/gfortran
---------------------
Building gcc from source code can be a difficult undertaking.  Refer to the
detailed directions at  http://gcc.gnu.org/install/ for further help.

Building fftw-3.2.2
-------------------
Get fftw-3.2.2 from: http://www.fftw.org/fftw-3.2.2.tar.gz
Untar the file fftw-3.2.2.tar.gz using
tar -zxvf fftw-3.2.2.tar.gz
cd fftw-3.2.2
then run ./configure --enable-single --enable-shared --prefix=<directory>
where <directory> is the full path to an installation location where you have
write access. Then run,

make
make install

Building Python
---------------
Get the Python source code from http://www.python.org/ftp/python/3.3.5/Python-3.3.5.tgz

Untar the file Python-3.3.5.tgz using

tar -zxvf Python-3.3.5.tgz
cd Python-3.3.5

Then run

./configure --prefix=<directory>

where <directory> is the full path to an installation location where you
have write access.  Then run,

make
make install

Builing scons
At this time scons only works with Python2. The scons developers have
announced that they are working on a Python3 version of scons.  In the
meantime, you should have Python2.6 or Python2.7 available to you by
default if your computer is new enough.  Otherwise repeat the above
steps with 3.3.5 replaced with 2.7.8.

Get scons http://prdownloads.sourceforge.net/scons/scons-2.0.1.tar.gz
Untar the file scons-2.0.1.tar.gz using
tar -zxvf scons-2.0.1.tar.gz
cd scons-2.0.1.tar.gz
Then, using the version of Python you just built, run

python2.6 setup.py build
python2.6 setup.py install

Building hdf5 [Only necessary for COSMO-SkyMed support]
-------------
Get the source code from:
http://www.hdfgroup.org/ftp/HDF5/current/src/hdf5-1.8.6.tar.gz

Building h5py [Only necessary for COSMO-SkyMed support]
Get the h5py source code from:
http://code.google.com/p/h5py/downloads/detail?name=h5py-1.3.1.tar.gz


Building gdal-bindings [Only necessary for Radarsat2, Tandem-X and Sentinel 1A]
----------------
On most linux distributions, gdal can installed along with its python bindings
using standard repository management tools.

If you don't have gdal, you can find instructions on building GDAL here
http://trac.osgeo.org/gdal/wiki/BuildHints

Remember to use configure with --with-python option to automatically build
python bindings.

Else, if you already have gdal installed on your system but without python
buindings, use easy_install corresponding to your python 3 version. You may
need to setup LD_LIBRARY_PATH correctly to include path to libgdal.so

easy_install GDAL


Building SpiceyPy  [Only necessary for Radarsat1]
----------------
JPL's CSPICE library (http://naif.jpl.nasa.gov/naif/toolkit_C.html) is needed
for this. Follow instructions at https://github.com/Apollo117/SpiceyPy to
install SpiceyPy, after installing CSPICE.


Once all these packages are built, you must setup your PATH and LD_LIBRARY_PATH
variables in the unix shell to ensure that these packages are used for compiling
and linking rather than the default system packages.

================================================================================
2. Building ISCE
================================================================================

--------------------------------------------------------------------------------
2.1 Configuration control: SCONS_CONFIG_DIR and SConfigISCE
--------------------------------------------------------------------------------

Scons requires that configuration information be present in a directory
specified by the environment variable SCONS_CONFIG_DIR.  First, create a
build configuration file, called SConfigISCE and place it in your chosen
SCONS_CONFIG_DIR.  The SConfigISCE file should contain the following
information, note that the #-symbol denotes a comment and does not need
to be present in the SConfigISCE file:

# The directory in which ISCE will be built
PRJ_SCONS_BUILD = $ISCE_BUILD_ROOT/isce
# The directory into which ISCE will be installed
PRJ_SCONS_INSTALL = $ISCE_INSTALL_ROOT/isce
# The location of libraries, such as libstdc++, libfftw3
LIBPATH = $HOME/lib64 $HOME/lib
# The location of Python.h
CPPPATH = $HOME/include/python2.7
# The
#FORTRANPATH =  $HOME/python/src/isce/include
# The location of your Fortran compiler
FORTRAN = $HOME/bin/gfortran
# The location of your C compiler
CC = $HOME/bin/gcc
# The location of your C++ compiler
CXX = $HOME/bin/g++

#libraries needed for mdx display utility
MOTIFLIBPATH = /opt/local/lib       # path to libXm.dylib
X11LIBPATH = /opt/local/lib         # path to libXt.dylib
MOTIFINCPATH = /opt/local/include   # path to location of the Xm
                                    # directory with various include files (.h)
X11INCPATH = /opt/local/include     # path to location of the X11 directory
                                    # with various include files

In the above listing of the SConfigISCE file,  $ISCE_BUILD_ROOT and
$ISCE_INSTALL_ROOT may be actual environment variables that you create or else
you can replace them with the actual paths you choose to use for the build files
and the install files.  Also, in the following the capitalization of 'isce' as
lower case does matter.  This is the case-sensitive package name that Python
code uses for importing isce.

--------------------------------------------------------------------------------
2.2 Install ISCE
--------------------------------------------------------------------------------

Untar the file isce.tar.gz
cd isce
scons install

For a verbose install run:
scons -Q install

The scons command also allows you to explicitly specify the name of the
SConfigISCE file, which could be used to specify an alternative file for
(say SConfigISCE_NEW) which must still be  located in the same
SCONS_CONFIG_DIR, run

scons install --setupfile=SConfigISCE_NEW

This will build the necessary components and install them into the location
specified in the configuration file as PRJ_SCONS_INSTALL.

--------------------------------------------------------------------------------
2.3 Setup Your Environment
--------------------------------------------------------------------------------

Once everything is installed, you will need to set the following environment
variables to run the programs included in ISCE ($ISCE_INSTALL_ROOT may be an
environment variable you created in 2.1 above or else replace it with the actual
path to where you installed ISCE):

export PYTHONPATH=$ISCE_INSTALL_ROOT:$PYTHONPATH

and to put the executable commands in the ISCE applications directory on your
PATH for convenience,

export ISCE_HOME=$ISCE_INSTALL_ROOT/isce
export PATH=$ISCE_HOME/applications:$PATH

An optional environment variable is $ISCEDB.  This variable points to a
directory in which you may place xml files containing global preferences. More
information on this directory and the files that you might place there is
given below in Section 4.  For now you can ignore this environment variable.

To test your installation and your environment, do the following:

> python3
>>> import isce
>>> isce.version.release_version


================================================================================
3. Running ISCE
================================================================================

---------------------------------------------------------------------------------
3.1 Running ISCE from the command line
---------------------------------------------------------------------------------

Copy the example xml files located in the example directory in the ISCE source
tree to a working directory and modify them to point to your own data.  Run
them using the command:

> $ISCE_HOME/applications/insarApp.py isceInputFile.xml

or (with $ISCE_HOME/applications on your PATH) simply,

> insarApp.py isceInputFile.xml

The name of the input file on the command line is arbitrary.  ISCE also looks
for appropriately named input files in the local directory

You can also ask ISCE for help from the command line:

> insarApp.py --help

This will tell you the basic command and the options for the input file.
Example input files are also given in the 'examples/input_files' directory.

As explained in the Component Configurability section below, it is also possible
to run insarApp.py without giving an input file on the command line.  ISCE will
automatically find configuration files for applications and components if they
are named appropriately.

---------------------------------------------------------------------------------
3.2 Running ISCE in the Python interpreter
---------------------------------------------------------------------------------

It is also possible to run ISCE from within the Python interpreter.  If you have
an input file named insarInputs.xml you can do the following:

%> python3
>>> import isce
>>> from insarApp import Insar
>>> a = Insar(name="insarApp", cmdline="insarInputs.xml")
>>> a.configure()
>>> a.run()

(As explained in the Component Configurability section below, if the file
insarInputs.xml were named insarApp.xml or insar.xml, then the 'cmdline' input
on the line creating 'a' would not be necessary.  The file 'insarApp.xml' would
be loaded automatically because when 'a' is created above it is given the name
'insarApp'.  A file named 'insar.xml' would also be loaded automatically if it
exists because the code defining insarApp.py gives all instances of it the
'family' name 'insar'.  See the Component Configurability section below for
details.)

---------------------------------------------------------------------------------
3.3 Running ISCE with steps
---------------------------------------------------------------------------------

An other way to run ISCE is the following:

insarApp.py insar.xml --steps

This will run insarApp.py from beginning to end as is done without the
--steps option, but with the added feature that the workflow state is
stored in files after each step in the processing using Python's pickle
module. This method of running insarApp.py is only a little slower
and it uses extra disc space to store the pickle files, but it
provides some advantage for debugging and for stopping and starting a
workflow at any predetermined point in the flow.

The full options for running insarApp.py with steps is the following:

insarApp.py insar.xml [--steps] [--start=<s>] [--end=<s>] [--dostep=<s>]


where <s> is the name of a step.  To see the full ordered list of steps
the user can issue the following command:

insarApp.py insar.xml --steps --help

The --steps option was explained above.
The --start and --end option can be used together to process a range of steps.
The --dostep option is used to process a single step.

For the --start and --dostep options to work, of course, requires that the
steps preceding the starting step have been run previously because the
state of the work flow at the beginning of the first step to be run must
be stored from a previous run.

An example for using steps might be to execute the end-to-end workflow
with --steps to store the state of the workflow after every step as in,

insarApp.py insar.xml --steps

Then use --steps to rerun some of the steps (perhaps you made a code
modification for one of the steps and want to test it without starting
from the beginning) as in

insarApp.py insar.xml --start=<step-name1> --end=<step-name2>

or to rerun a single step as in

insarApp.py insar.xml --dostep=<step-name>

Running insarApp.py with --steps also enables one to enter the Python
interpreter after a run and load the state of the workflow at any stage
and introspect the objects in the flow and play with them as follows,
for example:

%> python3
>>> import isce
>>> f = open("PICKLE/formslc")
>>> import pickle
>>> a = pickle.load(f)
>>> o = f.getMasterOrbit()
>>> t, x, p, off = o._unpackOrbit()
>>> print t
>>> print x
>>>

Someone with familiarity of the inner workings of ISCE can exploit
this mode of interacting with the pickle object to discover much about
the workflow states and also to edit the state to see its effect
on a subsequent run with --dostep or --start.

---------------------------------------------------------------------------------
3.4 NOTE on DEM
---------------------------------------------------------------------------------

- If a dem component is provided but the dem is the EGM96 geo reference
  (which is the case for SRTM DEMs) it will be converted into  WGS84.
  A new file with suffix wgs84 is created. If it is already in WGS84
  nothing happens.
- If no dem component is specified in input a EGM96 will be downloaded
  and the it will be converted into WGS84. There will be then two files,
  an EGM96 with no suffix, and the WGS84 with the wgs84 suffix.



================================================================================
4. Input Files
================================================================================

Input files are structured 'xml' documents.  This section will briefly
introduce their structure using a special case appropriate for processing ALOS
data.  Examples for the other sensor types can be found in the directory
'examples/input_files'.

The basic (ALOS) input file looks like this (indentation is optional):

insarApp.xml:
-------------
<insarApp>
<component name="insarApp">
    <property name="sensor name">ALOS</property>
    <component name="Master">
        <property name="IMAGEFILE">
            /a/b/c/20070215/IMG-HH-ALPSRP056480670-H1.0__A
        </property>
        <property name="LEADERFILE">
            /a/b/c/20070215/LED-ALPSRP056480670-H1.0__A
        </property>
        <property name="OUTPUT">20070215.raw </property>
    </component>
    <component name="Slave">
        <property name="IMAGEFILE">
            /a/b/c/20061231/IMG-HH-ALPSRP049770670-H1.0__A
        </property>
        <property name="LEADERFILE">
            /a/b/c/20061231/LED-ALPSRP049770670-H1.0__A
        </property>
        <property name="OUTPUT">20061231.raw </property>
    </component>
</component>
</insarApp>

The data are enclosed between an opening tag and a closing tag.  The <insarApp>
tag is closed by the </insarApp> tag for example.  This outer tag is necessary
but its name has no significance.  You can give it any name you like.  The
other tags, however, need to have the names shown above.  There are 'property',
and 'component' tags shown in this example.

The component tags have names that match a Component name in the ISCE code.
The component tag named 'insarApp' refers to the configuration information for
the Application (which is a Component) named "insarApp".  Components contain
properties and other components that are configurable.  The property tags
give the values of a single variable in the ISCE code.  One of the properties
defined in insarApp.py is the "sensor name" property.  In the above example
it is given the value ALOS.  In order to run insarApp.py two images need to
be specified.  These are defined as components named 'Master' and 'Slave'.
These components have properties named 'IMAGEFILE', 'LEADERFILE', and 'OUTPUT'
with the values given in the above example.

NOTE: the capitalization of the property and component names are not of any
importance.  You could enter 'imagefile' instead of 'IMAGEFILE', for example,
and it would work correctly.  Also extra spaces in names that include spaces,
such as "sensor name" do not matter.

There is a lot of flexibility provided by ISCE when constructing these input
files through the use of "catalog" tags and "constant" tags.

A "catalog" tag can be used to indicate that the contents that would normally
be found between an opening ad closing "component" tag are defined in another
xml file.  For example, the insarApp.xml file shown above could have been split
between three files as follows:

insarApp.xml
------------
<insarApp>
    <component name="insar">
        <property  name="Sensor name">ALOS</property>
        <component name="master">
            <catalog>20070215.xml</catalog>
        </component>
        <component name="slave">
            <catalog>20061231.xml</catalog>
        </component>
    </component>
</insarApp>

20070215.xml
------------
<component name="Master">
    <property name="IMAGEFILE">
        /a/b/c/20070215/IMG-HH-ALPSRP056480670-H1.0__A
    </property>
    <property name="LEADERFILE">
        /a/b/c/20070215/LED-ALPSRP056480670-H1.0__A
    </property>
    <property name="OUTPUT">20070215.raw </property>
</component>

20061231.xml
------------
<component name="Slave">
    <property name="IMAGEFILE">
        /a/b/c/20061231/IMG-HH-ALPSRP049770670-H1.0__A
    </property>
    <property name="LEADERFILE">
        /a/b/c/20061231/LED-ALPSRP049770670-H1.0__A
    </property>
    <property name="OUTPUT">20061231.raw</property>
</component>


A "constant" tag can be used to define a constant for convenience inside
an xml file.  For example, the dates '20070215' and '20061231' are used
multiple times in the above files.  Also, the base path '/a/b/c/' is used
multiple times.  A constant defined in a constant tag is used in constructing
values by sandwiching it between two '$' symbols.  For example, if a constant
named "date1" is defined then to use it we would enter '$date1'.  The following
example insarApp.xml file should make this clear:

insarApp.xml
------------
<insarApp>
<constant name="dir">/a/b/c </constant>
<constant name="date1">20070215</constant>
<constant name="date2">20061231</constant>
<constant name="dir1">$dir$/$date1$</constant>
<constant name="dir2">$dir$/$date2$</constant>
<component name="insarApp">
    <property name="sensor name">ALOS</property>
    <component name="Master">
        <property name="IMAGEFILE">
            $dir1$/IMG-HH-ALPSRP056480670-H1.0__A
        </property>
        <property name="LEADERFILE">
            $dir1$/LED-ALPSRP056480670-H1.0__A
        </property>
        <property name="OUTPUT">$date1$.raw </property>
    </component>
    <component name="Slave">
        <property name="IMAGEFILE">
            $dir2$/IMG-HH-ALPSRP049770670-H1.0__A
        </property>
        <property name="LEADERFILE">
            $dir2$/LED-ALPSRP049770670-H1.0__A
        </property>
        <property name="OUTPUT">$date2$.raw </property>
    </component>
</component>
</insarApp>

Note: as of the time of this release constants do not work with catalog files.
This will be fixed in a future release.

================================================================================
5. Component Configurability
================================================================================

In the examples for running insarApp.py (Section 3.1 and 3.3 above) the input
data were entered by giving the name of an 'xml' file on the command line.  The
ISCE framework parses that 'xml' file to assign values to the configurable
variables in the isce Application insarApp.py.  The Application executes
several steps in its workflow.  Each of those steps are handled by a Component
that is also configurable from input data.  Each component may be configured
independently from user input using appropriately named and placed xml files.
This section will explain how to name these xml files and where to place them.

----------------------------------------------------------------------------
5.1 Component Names: Family and Instance
----------------------------------------------------------------------------

Each configurable component has two "names" associated with it.  These names
are used in locating possible configuration xml files for those components. The
first name associated with a configurable component is its "family" name.  For
insarApp.py, the family name is "insar".  Inside the insarApp.py file an
Application is created from a base class named Insar.  That base class defines
the family name "insar" that is given to every instance created from it.  The
particular instance that is created in the file insarApp.py is given the
'instance name' 'insarApp'.  If you look in the file near the bottom you will
see the line,

insar = Insar(name="insarApp")

This line creates an instance of the class Insar (that is given the family name
'insar' elsewhere in the file) and gives it the instance name "insarApp".

Other applications could be created that could make several different instances
of the Insar.  Each instance would have the family name "insar" and would be
given a unique instance name.  This is possible for every component.  In the
above example xml files instances name "Master" and "Slave" of a family named
"alos" are created.

----------------------------------------------------------------------------
5.2 Component Configuration Files: Locations, Names, Priorities
----------------------------------------------------------------------------

The ISCE framework looks for xml configuration files when configuring every
Component in its flow in 3 different places with different priorities.  The
configuration sequence loads configuration parameters found in these xml files
in the sequence lowest to highest priority overwriting any parameters defined
as it moves up the priority sequence.  This layered approach allows a couple
of advantages.  It allows the user to define common parameters for all instances
in one file while defining specific instance parameters in files named for those
specific instances.  It also allows global preferences to be set in a special
directory that will apply unless the user overrides them with a higher priority
xml file.

The priority sequence has two layers.  The first layer is location of the xml
file and the second is the name of the file.  Within each of the 3 location
priorities indicated below, the filename priority goes from 'family name' to
'instance name'.  That is, within a given location priority level, a file
named after the 'family name' is loaded first and then a file with the
'instance name' is loaded next and overwrites any property values read from the
'family name' file.

The priority sequence for location is as follows:

(1)  The highest priority location is on the command line.  On the command line
the filename can be anything you choose.  Configuration parameters can also be
entered directly on the command line as in the following example:

> insarApp.py insar.master.output=master_c.raw

This example indicates that the variable named 'output' of the Component
named 'master' belonging to the Component (or Application) named 'insar'
will be given the name "master_c.raw".

The priority sequence on the command line goes from lowest priority on the left
to highest priority on the right.  So, if we use the command line,

> insarApp.py myInputFile.xml insar.master.output=master_c.raw

where the myInputFile.xml file also gives a value for the insar master output
file as master_d.raw, then the one defined on the right will win, i.e.,
master_c.raw.

(2) The next priority location is the local directory in which insarApp.py is
executed.  Any xml file placed in this directory named according to either the
family name or the instance name for any configurable component in ISCE will be
read while configuring the component.

(3) If you define an environment variable named $ISCEDB, you can place xml files
with family names or instance names that will be read when configuring
Configurable Components.  These files placed in the $ISCEDB directory have the
lowest priority when configuring properties of the Components.  The files placed
in the ISCEDB directory can be used to define global settings that will apply
unless the xml files in the local directory or the command line override those
preferences.

----------------------------------------------------------------------------
5.2 Component Configuration Structure
----------------------------------------------------------------------------

However, the component tag has to have the family name of the Component/
Application.  In the above examples you see
that the outermost component tag has the name "insar", which is the family name
of the class Insar of which insarApp is an instance.


----------------------------------------------------------------------------
5.3 Component Configuration Help
----------------------------------------------------------------------------

At this time there is limited information about component configurability
through the command

> insarApp.py --help

Future deliveries will improve this situation.  In the meantime we describe
here how to discover from the code which Components and parameters are
configurable.  One note of caution is that it is possible for a parameter
to appear to be configurable from user input when the particular flow will
not allow this degree of freedom.  Experience and evolving documentation will
be of use in determining these cases.

How to find out whether a component is configurable, what its configurable
parameters are, what "name" to use in the xml file, and what name to give to
the xml file.

Let's take as an example, Nstage.py, which is in components/mroipac/ampcor.

Open it in an editor and search for the string "class Nstage".  It is on
line 243.  You will see that it inherits from Component.  This is the minimum
requirement for it to be a configurable component.

Now look above that line and you will see several variable names being set
equal to a call to Component.Parameter.  These declarations define these
variables as configurable parameters.  They are entered in the "parameter_list"
starting on line 248.  That is the method by which these Parameters are made
configurable parameters of the Component Nstage.

Each of the parameters defines the "public_name", which is the "name" that you
would enter in the xml file.  For instance if you want to set the gross offset
in range, which is defined starting on line 130 in the variable
ACROSS_GROSS_OFFSET, then you would use an xml tag like the following (assuming
you have determined that the gross offset in range is about 150 pixels):

<property name="ACROSS_GROSS_OFFSET">150</property>


Now, to determine what to call the xml file and what "name" to use in the
component tag.  A configurable component has a "family" name and an incidence
"name".  It is registered as having these names by calling the
Component.__init__ constructor, which is done on line 672.  On that line you
will see that the call to __init__ passes  'family=self.__class__.family' and
'name=name' to the Component constructor (super class of Nstage).  The family
name is given as "nstage" on line 245.  The instance name is passed as the
value of the 'name=name' and was passed to it from whatever program created it.
Nstage is created in  components/isceobj/InsarProc/runOffsetprf_nstage.py where
it is given the name 'insarapp_slcs_nstage'  on line 107 and also in
components/isceobj/InsarProc/runRgoffset_nstage.py where it is given the name
'insarapp_intsim_nstage' on line 58.  If you are setting a parameter that
should be the same for both of these uses of Nstage, then you can use the
family name 'nstage' for the name of the xml file as 'nstage.xml'.  It is more
likely that you will want to use the instance names, 'insarapp_slcs_nstage.xml'
and 'insarapp_intsim_nstage.xml'.  Use the family name 'nstage' for the
component tag 'name'.

Example for SLC matching use of Nstage:

Filename: insarapp_slcs_nstage.xml:
<dummy>
<component name="nstage">
    <property name="ACROSS_GROSS_OFFSET">150</property>
</component>
</dummy>

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