A 3D image sensor include a depth pixel and at least two polarization pixels adjacent to the depth pixel. The depth pixel includes a charge generation region in a substrate. The depth pixel is configured to generate depth information associated with a depth of an object from the 3D image sensor in a 3D scene based on detecting light reflected from the object. Each polarization pixel includes a photodiode in the substrate and a polarizer on the substrate in a light-incident direction. The polarization pixel is configured to generate shape information associated with a shape of a surface of the object in the 3D scene based on detecting light reflected from the object. The polarization pixels and the depth pixel collectively define a unit pixel. The respective polarizers are associated with different polarization directions.