System that facilitates rapid onboarding of an autonomous (cashier-less) store by capturing images of the store's items from multiple angles, with varying background colors, and that builds a classifier training dataset from these images. Background surfaces may for example be coated with retroreflective tape or film, and variable-color incident light sources may generate the desired background colors. Embodiments may automatically rotate or otherwise reorient the item placed in the onboarding system, so that a relatively small number of cameras can capture views from multiple angles. When an item is placed in the system, a fully automated process may generate a sequence of item orientations and background colors, and may capture and process images from the cameras to create training images. Images of the item from multiple angles, under varying lighting conditions, may be captured without requiring an operator to move or reorient the item.