So you are interesting in downloading satellite images? Let's start from the top by defining a satellite image.
Satellite images or in a more scientific terminology, satellite remote sensing images, are data in the form of images that are collected using satellites in orbit around the Earth.
In terms of images we mean the recorded spectrum (reflected or emitted) of objects in a gridded format. This translates to a matrix with rows and columns which cover a specific geospatial extent. Each recorded spectrum is a different matrix.
So if we record the well known true color images, we have three matrices of equal dimensions.
There are many remote sensing satellites orbiting the Earth, that capture different types of images.
We have 3 main types of satellites:
- Optical (multispectral and hyperspectral)
- Synthetic Aperture RADAR (SAR)
In every case there are commercial and "open" satellites that provide images with different specifications.
In this article we will focus on the "open" satellites. With the term open, we mean satellites that provide data for free.
The European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) are two major providers of free and open data.
They have developed and operated the following satellites from where you can download images:
- Landsat (NASA)
- MODIS (NASA)
- Sentinels (1-5) (ESA)
In the following videos we will show you how to download satellite images using different providers. All these videos are also part of our courses, so if you want to learn what to do after you have downloaded the images, just go to a specific course and enroll!