This article presents an investigation of the impact of camera warm-up on the image acquisition process and therefore on the accuracy of segmented image features. Based on an experimental study we show that the camera image is shifted to an extent of some tenth of a pixel after camera start-up. The drift correlates with the temperature of the sensor board and stops when the camera reaches its thermal equilibrium. A further study of the observed image flow shows that it originates from a slight displacement of the image sensor due to thermal expansion of the mechanical components of the camera. This sensor displacement can be modeled using standard methods of projective geometry in addition with bi-exponential decay terms to model the temporal dependence. The parameters of the proposed model can be calibrated and then used to compensate warm-up effects. Further experimental studies show that our method is applicable to different types of cameras and that the warm-up behaviour is characteristic for a specific camera.
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