pyTVDI

Synopsis

This project contains Python code for computing the Temperature-Vegetation Dryness Index for assessing soil moisture and evaporative fraction with remote sensing data combining a vegetation index and radiometric surface temperature.

The project consists of:

1. lower-level modules with the basic functions needed in TVDI calculation.

2. higher-level scripts for easily running pyTVDI from imagery.

Installation

Download the project to your local system, enter the download directory and then type

python setup.py install.

if you want to install pyTVDI and its low-level modules in your Python distribution.

The following Python libraries will be required for running pyTVDI:

• Numpy
• GDAL

Code Example

High-level example

The easiest way to get a feeling of pyTVDI and its configuration is through the provided ipython/jupyter notebooks. In a terminal shell, navigate to your working folder and type

• jupyter notebook TVDIgui.ipynb.

In addition, you can also run TVDI with the scripts MAIN_TVDI.py, which will read an input configuration file (defaults are Config_TVDI.txt). You can edit these configuration files or make a copy to fit your data and site characteristics and either run any of these two scripts in a Python GUI or in a terminal shell:

• python MAIN_TVDI.py <configuration file>..

where <configuration file> points to a customized configuration file... leave it blank if you want to use the default file Config_TVDI.txt.

Low-level example

You can obtain TVDI/EF images by importing the module tvdi, which contains all the methods for estimating the dry and wet edges and computing TVDI or Evaporative Fraction.

import pyTVDI 
output=pyTVDI.tvdi(io_inf, roi_inf, alg_inf)

You can type help(pyTVDI.tvdi) to understand better the inputs needed and the outputs returned

Basic Contents

High-level modules

• .src/pyTVDI.py, class object for TSEB scripting.
• TVDI_GUI.ipynb notebook for using pyTVDI and configuring TSEB through a Graphical User Interface, GUI.
• MAIN_TVDI.py, high level scripts for running TVDI through a configuration file (Config_TVDI.txt).

Low-level module

The low-level module in this project is aimed at providing customisation and more flexibility in running the Ts-VI triangle method. The following modules are included

• .src/pyTVDI.py.

core functions for running TVDI.

API Reference

http://pytvdi.readthedocs.org/en/latest/index.html

Main Scientific References

• Sandholt, I.; Rasmussen, K. & Andersen, J. A simple interpretation of the surface temperature/vegetation index space for assessment of surface moisture status. Remote Sensing of Environment , 2002, 79, 213 - 224.

• Stisen S.; Sandholt I.; Nørgaard A.; Fensholt R. & Jensen, K. Combining the triangle method with thermal inertia to estimate regional evapotranspiration - Applied to MSG-SEVIRI data in the Senegal River basin. Remote Sensing of Environment, 2008, 112, 1242-1255.

• de Tomás, A.; Nieto, H.; Guzinski, R.; Salas, J.; Sandholt, I. & Berliner, P. Validation and scale dependencies of the triangle method for the evaporative fraction estimation over heterogeneous areas. Remote Sensing of Environment , 2014, 152, 493 - 511.

Tests

The folder ./Input contains examples for running pyTVDI. Just run the high-level scripts with the configuration files provided by default and compare the resulting outputs with the files stored in ./Output/

Contributors

• Hector Nieto hnieto@ias.csic.es hector.nieto.solana@gmail.com main developer
• Radoslaw Guzinski main developer
• Inge Sandholt TVDI principal investigator

License

pyTVDI: a Python Temperature-Vegetation Dryness Index

Copyright 2016 Hector Nieto and contributors.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.