Using cameras for precise measurement of two-dimensional plant features: CASS

Abstract

Images are used frequently in plant phenotyping to capture measurements. This chapter offers a repeatable method for capturing two-dimensional measurements of plant parts in field or laboratory settings using a variety of camera styles (cellular phone, DSLR), with the addition of a printed calibration pattern. The method is based on calibrating the camera using information available from the EXIF tags from the image, as well as visual information from the pattern. Code is provided to implement the method, as well as a dataset for testing. We include steps to verify protocol correctness by imaging an artifact. The use of this protocol for two-dimensional plant phenotyping will allow data capture from different cameras and environments, with comparison on the same physical scale. We abbreviate this method as CASS, for CAmera aS Scanner.

Automated Size Measurements of Halyomorpha halys (Stål) (Heteroptera: Pentatomidae) with Simple Image-Based Methodology

“…The arUco patterns were 11.76 mm 2 . CAmera aS Scanner (Tabb et al 2019;Tabb 2020), a method for calibrating cameras, was used to convert the image from pixels with an unknown physical size to pixels with a per mm scaling, similar to the type of images given by a flatbed scanner (the scaling is 10 pixels per mm for this study). CAmera aS Scanner requires that a calibration pattern is in the scene and camera metadata is available.…”