An apparatus for computing a three-dimensional model of an object, comprising: at least one directional energy source arranged to generate electromagnetic radiation and to directionally illuminate the object from at least three directions; one or more energy sensors arranged to capture images of the object; a processor arranged to receive images captured by the energy sensors, and control the energy sources and the at least one energy sensor; the processor being arranged: (i) to control the at least one energy source and one or more energy sensors to capture, for each direction, a first image at a respective first time at which the at least one energy source illuminates the object from the respective direction with a first respective intensity level, (ii) to analyze the first images to obtain an energy intensity ratio; (iii) to control the at least one energy source and one or more energy sensors to capture, for each direction, a second image at a respective second time at which the at least one energy source generates energy at a second respective intensity level, the ratio of the second and first respective intensity levels being equal to the energy intensity ratio; (iv) to obtain photometric data using the first and second captured images; and (v) to generate the 3D model using the photometric data. at least one directional energy source arranged to generate electromagnetic radiation and to directionally illuminate the object from at least three directions; one or more energy sensors arranged to capture images of the object; a processor arranged to receive images captured by the energy sensors, and control the energy sources and the at least one energy sensor; the processor being arranged: (i) to control the at least one energy source and one or more energy sensors to capture, for each direction, a first image at a respective first time at which the at least one energy source illuminates the object from the respective direction with a first respective intensity level, (ii) to analyze the first images to obtain an energy intensity ratio; (iii) to control the at least one energy source and one or more energy sensors to capture, for each direction, a second image at a respective second time at which the at least one energy source generates energy at a second respective intensity level, the ratio of the second and first respective intensity levels being equal to the energy intensity ratio; (iv) to obtain photometric data using the first and second captured images; and (v) to generate the 3D model using the photometric data. (i) to control the at least one energy source and one or more energy sensors to capture, for each direction, a first image at a respective first time at which the at least one energy source illuminates the object from the respective direction with a first respective intensity level, (ii) to analyze the first images to obtain an energy intensity ratio; (iii) to control the at least one energy source and one or more energy sensors to capture, for each direction, a second image at a respective second time at which the at least one energy source generates energy at a second respective intensity level, the ratio of the second and first respective intensity levels being equal to the energy intensity ratio; (iv) to obtain photometric data using the first and second captured images; and (v) to generate the 3D model using the photometric data.