A method of measuring the absolute pose parameters of a moving rigid body using a monocular camera is proposed, aiming at addressing calibration difficulties and inconsistencies of repeated measurements of the rigid-body pose for a camera having a varying focal length. The proposed method does not require calibration beforehand. Using more than six non-coplanar control points symmetrically arranged in the rigid-body and world coordinate systems, the matrices of rotation and translation between the camera and two coordinate systems are obtained and the absolute pose of the rigid body measured. In this paper, formulas of the absolute pose measurement of a moving rigid body are deduced systematically and the complete implementation is presented. Position and attitude measurement experiments carried out on a three-axis precision turntable show that the average absolute error in the attitude angle of a moving rigid body measured by an uncalibrated camera at different positions changes by no more than 0.2 degrees. Analysis of the three-dimensional coordinate errors of the centroid of a moving rigid body shows little deviation in measurements made at three camera positions, with the maximum deviation of the average absolute error being 0.53 cm and the maximum deviation of the standard deviation being 0.66 cm. The proposed method can measure the absolute pose of a rigid body and is insensitive to the position of the camera in the measurement process. This work thus provides guidance for the repeated measurement of the absolute pose of a moving rigid body using a monocular camera.

Transplant of human cancer cells into zebrafish larvae has emerged as a useful methodology in cancer research. Zebrafish have very low husbandry costs, are amenable to large-scale drug screening, and are unmatched for optical clarity in live animal imaging. However, there is currently no consensus on the ideal methods for xenograft of human cancer cells into zebrafish. Here, we have examined the effects of transplant site and housing temperature on both zebrafish larvae and human cancer cells using survival analyses, metabolomic approaches, and in vivo imaging. Our data show that while zebrafish larvae can adapt to the ideal conditions for mammalian cells, human cancer cells are highly sensitive to both temperature change and transplant site. Human cells housed in slightly cooler than physiologic temperatures had a significantly altered metabolism that resulted in changes in growth, survival, and response to chemotherapy. Cancer cells xenografted into the yolk of the larvae also had reduced proliferation and drug response compared to those xenografted into the soma, in part due to the differences in metabolites available at these sites. In total, temperature and transplant site can have profound effects on xenografted cells. Standardization of zebrafish xenograft methods will enhance data reproducibility between individual laboratories.