Image Analysis

Introduction

Below are sources, software and methods for obtaining, accessing, processing and using satellite images. Be warned that some of these files and applications are large, and may take awhile to download and install.

Obtaining Images

  • Google Earth provides a simple way to get basic images with some historical depth. Sometimes it is good enough. Other times it’s imagery can be useful for prototyping.
  • ESA Sentinel satellite images
  • Copernicus Open Access Hub
  • DHuS Open Source Portal (advanced)
  • NASA AVARIS (airborne visible, infrared and hyperspectral images)
  • Planet Labs Explorer (some free images)
  • Digitalglobe (some free)

Lists of sources:

File Types & Viewing/Access Software

Google Earth

An easy way to get free imagery, although quite limited in what is freely available. Try it on your own! Google Earth.

ESA Sentinal

There are five ESA Sentinel missions, each of which concentrate on different capabilities.

  1. Let’s look at visible images (with some InfraRed)
  2. Install the Sentinel 2 – Toolbox

HDF

Hierarchical Data Format: Wikipedia.

HDFview HDF file viewing software

Processing Images Using Python

You can process images by using the Python programming language. The Python Image Library (PIL) makes some analysis relatively easy.

  1. Make sure that you have a text editor on your computer. It should be able edit and save pure text. Applications such as MS Word are not very good at this. Applications such as Xcode or Textmate are suitable.
  2. Make sure you have a terminal application on your computer. It might be called Terminal or HyperTerminal. If not, install a terminal program for your computer.
  3. Make sure that you have Python 1.5.2 or newer installed on your computer. To check, open your terminal application and enter python –version
  4. If you need to get or upgrade Python, click here.
  5. Download, uncompress and move the file to your working directory: PIL_test.py
  6. Run that file in your terminal with the command python PIL_test.py
  7. If the file says that PIL or Image are missing, download the library from here.
  8. PIL documentation can be found here.
  9. Download these files:color-index-reader_R-B_05_iraq_clean copy.py

 

 

Hyperspectral Images and Analysis

 

TNTmips is GIS software that has a hyperspectral analysis component. There is a free version.

USGS Spectral Library

JPL ASTER spectral library

Other

Koolock (infrared)

GeoOptics (weather, water gravity)

AGI Systems Tool Kit STK (project satellite orbits and missions)

 

Galleries

  • http://www.digitalglobe.com/products/firstlook
  • Landcover gallery