In outdoor environments shadows are common. These typically strong visual features cause considerable change in the appearance of a place, and therefore confound vision- based localisation approaches. In this work  we describe how to convert a colour image of the scene to a greyscale invariant image where pixel values are a function of underlying material property not lighting. We summarise the theory of shadow invariant images and discuss the modelling and calibration issues which are important for non-ideal off-the-shelf colour cameras. We evaluate the technique with a commonly used robotic camera and an autonomous car operating in an outdoor environment, and show that it can outperform the use of ordinary greyscale images for the task of visual localisation.

dealing_with_shadows_image

 

  • [PDF] P. Corke, R. Paul, W. Churchill, and P. Newman, “Dealing with Shadows: Capturing Intrinsic Scene Appearance for Image-based Outdoor Localisation,” in Proc. of the International Conference on Intelligent Robots and Systems (IROS), 2013.
    [Bibtex]

    @inproceedings{CorkeIROS2013,
    Author = {Peter Corke and Rohan Paul and Winston Churchill and Paul Newman},
    Booktitle = {Proc. of the International Conference on Intelligent Robots and Systems (IROS)},
    Month = {November},
    Pdf = {http://www.robots.ox.ac.uk/~mobile/Papers/2013IROS_corke.pdf},
    Title = {Dealing with Shadows: Capturing Intrinsic Scene Appearance for Image-based Outdoor Localisation},
    Year = {2013}}