InstruPy

InstruPy is a python package to calculate observation data metrics for a given instrument and associated viewing geometry.

For a detailed description see the following articles (available in the literature folder):

1. V. Ravindra, S. Nag, "Instrument Data Metrics Evaluator for Tradespace Analysis of Earth Observing Constellations", IEEE Aerospace Conference, Big Sky, Montana, March 2020.

2. V. Ravindra, R. Ketzner and S. Nag, "Earth Observation Simulator (EO-Sim): An Open-Source Software for Observation Systems Design," 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021.

3. S. Nag, V. Ravindra, J.J. LeMoigne "Instrument Modeling Concepts for Tradespace Analysis of Satellite Constellations", IEEE Sensors Conference, Delhi, India, October 2018.

Install

Requires: Unix-like operating system (Linux (Ubuntu, CentOS...), Mac), python 3.8, pip, gfortran, make

The installation can be carried out in a conda environment using the below steps.

1. Install gfortran. and make See here.

• Linux:

  sudo apt update
  sudo apt install build-essential
  

  sudo apt install build-essential installs additional useful utilities like gcc, g++ and make

  If gfortran is not installed with build-essential, please run sudo apt install gfortran

• Mac: brew install gcc and brew install make

2. Have conda installed using the Miniconda or Anaconda distributions.

3. Create and activate a new conda environment with python. Install pip in the environment.

conda create --name foo python=3.8
conda activate foo
conda install pip

4. Run make from the root repo directory.

   All the dependencies are automatically installed. If any errors are encountered please check that the following dependencies are installed correctly.

   • numpy
   • pandas
   • scipy
   • sphinx
   • sphinx_rtd_theme==0.5.2
   • metpy
   • netCDF4
   • astropy
   • lowtran==2.4.1 (requires gfortran)

5. Run tests using the make runtest command and get the OK message.

6. Find the documentation in: instrupy/docs/_build/html/index.html

The present version of OrbitPy has been tested on Ubuntu 18.04.3.

Lowtran

Lowtran python package allows the execution of the LOWTRAN7 model. This is assumed to estimate the atmospheric losses for the visible and near-visible spectrum.

The package is is available publicly here: https://pypi.org/project/lowtran/

An backup copy is present in the third_party\lowtran-2.4.1 folder.

This package requires the gfortran Fortran compiler.

If a Fortran compiler is not already installed, install gfortran as follows:

• Linux: apt install gfortran

• Mac: brew install gcc

• Windows: https://www.scivision.dev/windows-gcc-gfortran-cmake-make-install/

Windows system

If using a Windows system, one may consider:

1. Setting up a virtual-machine with Ubuntu (or similar) OS.

   See tutorial here: https://ubuntu.com/tutorials/how-to-run-ubuntu-desktop-on-a-virtual-machine-using-virtualbox#1-overview

   Virtual Machines:

    *   VMware Workstation player is available free for non-commercial, personal or home use. VMWare tools may need to be installed separately  after the player installation. 
    [https://www.vmware.com/products/workstation-player/workstation-player-evaluation.html](https://www.vmware.com/products/workstation-player/workstation-player-evaluation.html)
   
    *   Another option is Oracle Virtual Box.
        [https://www.virtualbox.org/](https://www.virtualbox.org/)
   

2. Using Windows Subsytem for Linux (WSL)

   https://ubuntu.com/wsl

   https://docs.microsoft.com/en-us/windows/wsl/about

MacOS

If using homebrew on MacOS, gcc shall need to be installed: https://formulae.brew.sh/formula/gcc

gcc shall provide gfortran which is required by lowtran.

The gcc compiler may default to clang instead of gcc (although the displayed name when querying using which gcc shall point to a usr/bin/gcc folder, it is simply running clang).

One way to solve the problem is by adding alias:

Add these to ~/.zshrc file (if using zshrc) whichc an be found in the Home directory of the user:

alias gcc="gcc-11"
alias g++="g++-11"
alias cc="cc-11"
alias c++="c++-11"

(Substitute the correct gcc version number which has been installed by homebrew. gcc-11 is recommended since OrbitPy has been shown problems with gcc-13.)

Run gcc --version to verify what the correct gcc is being invoked.ß

Reference: Stack Overflow

Directory structure

C:.
├───docs
├───examples (example specs)
│   ├───example_instrument_specs
│
├───instrupy (primary source files)
├───tests (test scripts)
├───third_party
│   └───lowtran-2.4.1
├───literature (resources)
├───TBD (old files)

Examples

InstruPy contains models of 'basic', passive-optical, synthetic-aperture-radar and radiometer instruments. Each type of instrument is associated with different set of instrument parameters whose description can be found in the HTML documentation. Example specifications and related literature of instruments (in the required JSON format) is present in the instrupy/examples/ directory.

The directory also contains the following python scripts which can be executed after the InstruPy package has been installed.

• SAR_example.py: Illustrates the synthetic-aperture-radar models with different possible set of configurations and the usage of the InstruPy functions to evaluate the data-metrics.

License and Copyright

Copyright 2022 Bay Area Environmental Research Institute

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Credits and Acknowledgments

This work has been funded by grants from the National Aeronautics and Space Administration (NASA) Earth Science Technology Office (ESTO) through the Advanced Information Systems Technology (AIST) Program.

Questions?

Please contact Vinay (vravindra@baeri.org or vinay.ravindra@nasa.gov)