Updates in the Development of a Surface Reflectance Validation Camera System (CAMSIS)

This work describes recent changes and additions to the CAMSIS surface reflectance validation system (Vermote et al., 2019). In May 2019, CAMSIS was installed at the WLEF tower located in the Chequamegon National Forest, Wisconsin, as part of the CHEESEHEAD campaign (Vermote et al., 2020). This installation was a successful proof-of-concept of the feasibility of using ground-based imaging systems to validate satellite surface reflectance. The initial CAMSIS instrument counted with four monochrome cameras fitted with 470, 550, 650, and 850nm filters, and a 50% reflectance standard target mounted on an automated arm for the calibration of imagery to surface reflectance. While functional, the four-camera design added extra complexity to the data processing of the imagery, as each independent camera required specific georeferencing parameters and there was no practical way to implement dark current correction. Since then, the CAMSIS design has been updated (CAMSIS-II) to use a single monochrome camera and an electronic filter wheel fitted with the four spectral filters mentioned above and a custom light-blocking filter that allows to obtain dark current information at the time of image capture. CAMSIS-II was installed alongside CAMSIS at the WLEF tower in April 2022 for inter-calibration. Both instruments share a similar field of view and capture images simultaneously using the same calibration target.

References

Vermote, E., McCorkel, J., Rountree, W., Santamaria-Artigas, A., Skakun, S., Franch, B., Roger, J-C., 2019. Validation of high spatial resolution surface reflectance using a camera system (CAMSIS). AGU Fall Meeting 2019. San Francisco, CA, USA.

Vermote, E., McCorkel, J., Santamaria-Artigas, A., Rountree, W., Skakun, S., 2020. CAMSIS WLEF Surface Reflectance Dataset. https://doi.org/10.26023/4ECR-NGTP-1N0X.