Assessment of Standing Herbage Dry Matter Using A Range Imaging Sytem

Abstract

It has been known for a long time that a device that could quickly and accurately ascertain dry matter content would be very useful to pastoral farmers. Despite many years of various products being developed there is still a lack of consistent and accurate measurements available. We present a proof of concept using a time of flight imaging system to measure standing herbage dry matter. Scenes of herbage were captured using the SoftKinitec DS325 range imaging camera. Each scene included range and intensity images as well as colour images. Simple statistical analysis of the images was carried out and related to dry matter content. Twenty data points were gathered in late autumn growing conditions. The best correlation achieved was 0.9 with a standard deviation of 337 kgDM/ha. This was achieved used a multivariate linear regression. The predictors used were average depth, and standard deviations of both depth and intensity frames. The worst correlation achieved using a multivariate linear regression was 0.89 with a standard deviation of 365 kgDM/ha. Thirteen data points were also gathered during severe drought conditions. The same statistical analysis resulted in a best fit of 0.52 and a standard deviation of 533 kgDM/ha. Range cameras show promise when compared to currently available methods of dry matter measurement.