Hyperspectral camera calibration (2017–)

Metrology Research Institute studies the calibration methods of hyperspectral cameras in collaboration with Finnish Geospatial Research Institute (FGI) within Academy of Finland project "Quantitative remote sensing by 3D hyperspectral UAVs – From theory to practice".

Background

Each pixel of a typical digital color photograph contains the intensity levels of three color channels (red, green, and blue). By contrast, each pixel of a hyperspectral image contains data of several narrow wavelength channels across the electromagnetic spectrum. This enables more information to be extracted from images, which is why hyperspectral cameras can be used in several applications, such as mapping of forests, monitoring of the health of crops, and identifying different types of minerals. Many of the application require precise radiometric calibration of the hyperspectral cameras, which can be difficult due to the complexity of these instruments.

Metrology research group, hyperstectral camera by Aalto University
Hyperspectral camera attached to a goniometer that rotates the camera around to axis. The camera takes pictures at different angles of the opening of an integrating sphere luminance source located to the left of the camera.

Characterising uniformity of hyperspectral cameras

The sensitivity of a camera depends on the angle of the light incident on the system. For accurate radiometric measurements, the nonuniformity of hyperspectral cameras needs to be corrected. Metrology Research Institute has constructed a system to perform this flat-field correction. The system enables different correction geometries to be used and compared. This is useful when estimating the uncertainty related to the flatfield correction and the radiometric measurements in general.

Contact person: Alexander Kokka and Tomi Pulli

 

More information about the project can be found at the project website:

http://maanmittauslaitos.fi/en/node/9954

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