Abstract We propose an uncalibrated photometric stereo method that works with general and unknown isotropic re?ectances. Our method uses a pixel intensity pro?le, which is a sequence of radiance intensities recorded at a pixel across multi-illuminance images. We show that for general isotropic materials, the geodesic distance between intensity pro?les is linearly related to the angular difference of the surface normals, and that the intensity distribution of an intensity pro?le conveys information about the re?ectance properties, when the intensity pro?le is obtained under uniformly distributed directional lightings. Based on these observations, we show that surface normals can be estimated up to a convex/concave ambiguity. A solution method based on matrix decomposition with missing data is developed for a reliable estimation. Quantitative and qualitative evaluations of our method are performed using both synthetic and real-world scenes.