What should I expect from my SAR image?

When working with Synthetic Aperture Radar (SAR) images, there are several characteristics that you should expect to see. We highly recommend reviewing and understanding these unique characteristics before placing an order for a SAR image. 

Different Appearance than Optical Imagery: SAR images will look quite different than optical images as they will appear black and white instead of colored, since they are not affected by the visible light spectrum. Within these grayscale images, brighter areas indicate higher microwave reflectivity and darker areas indicate lower reflectivity. Additionally, because SAR interacts with surface roughness, texture, and structural angles, objects with strong angular features and geometric shapes will often appear prominent in the image while smooth areas, such as water, will provide little radar return.

Speckle Noise: SAR images are often affected by a type of noise called speckle, which appears as small, bright and dark spots scattered throughout the image. Speckle is caused by interference of the radar signal as it bounces off the Earth's surface.

Shadowing Effects: SAR images are generally acquired by a satellite looking to the side, rather than straight down, which can result in shadowing effects. As such, areas behind tall objects or steep terrain are not illuminated by the radar signal and appear as dark areas in the image. This can make it difficult to interpret features in the image and requires careful analysis and interpretation. The images are also typically oriented with the shadows down, which may make the image appear to be “upside down” or “on the side” from what you’d see in an optical image, which is oriented with “north up”. 

Complex Interpretability: SAR images can be more difficult to interpret than optical imagery due to their different appearance and the complex interactions between the radar signal and the Earth's surface.

In summary, when working with SAR images, you should expect to see grayscale images with speckle noise, different appearance than optical imagery, shadowing effects, and limited interpretability. However, with proper processing and interpretation techniques, SAR images can provide valuable information about the Earth's surface and its changes over time.