Comparison of Spatial Resolutions in Satellite Images
I wanted to better understand what is the difference between different spatial resolutions in satellite images. What can you really see in a 10 meter resolution image? What is the actual difference between 20 meter and 100 meter resolution? To get an answer for these questions I carried out a simple test.
How I did it
I used Sentinel-2A true color images (TCI) as baseline. These Sentinel-2 images have 10 meter resolution. Of course there are commercial satellites with better than 1 meter resolution but I wanted to concentrate on satellite data that is openly available for everyone. Four different 8 km x 8 km test scenes were tested:
- downtown San Francisco, California
- center pivot irrigation systems in Sahara desert
- Brahmaputra River in India
- Pukaki Lake in New Zealand
I downloaded the data from Amazon’s Sentinel-2 service. The coarser resolution images were constructed by downscaling the original 10 m x 10 m image and sharpening the resulting image a little bit. This is not exactly the same thing as taking images with instruments having different spatial resolutions but should be good enough to get an idea how different resolutions look like (also different interpolations etc. affect the results…).
Images with the following resolutions were constructed:
- 10 m (original image used here): e.g. Sentinel-2 red, green, blue bands
- 15 m: e.g. Landsat 7 & 8 panchromatic band
- 20 m: e.g. Sentinel-2 bands 5, 6, 7, 8a, 11, and 12
- 30 m: e.g. Landsat 4–5 TM bands (excl. thermal)
- 60 m: e.g. Sentinel-2 bands 1, 9, and 10, Landsat 1–5
- 100 m: e.g. Landsat 8 Thermal infrared bands
- 120 m: e.g. Landsat 4–5 thermal band
- 250 m: e.g. MODIS bands 1 and 2
The script for reproducing the images can be found below.
Test scene: San Francisco (8 km x 8 km)
Test scene: Center pivot irrigation systems in Sahara desert (8 km x 8 km)
Test scene: Brahmaputra river, India (8 km x 8 km)
Test scene: Lake Pukaki, New Zealand (8 km x 8 km)
Hope you liked the images. If you have any questions/comments/ideas, feel free to contact me (for example in Twitter).
All images contain modified Copernicus Sentinel data 2017.
