A method for discriminating and identifying, by 3D imaging, an object in a complex scene comprises the following steps: generating a sequence of 2D MIP images of the object, from a 3D voxel volume of the complex scene, this volume visualized by an operator by using an iterative process of MIP type from a projection plane and an intensity threshold determined by the operator on each iteration, automatically extracting, from the sequence of images, coordinates of a reduced volume corresponding to the sequence of images, choosing one of the intensity thresholds used during the iterations, automatically extracting, from the 3D volume of the complex scene, from the coordinates and chosen intensity threshold, a reduced 3D volume containing the object, automatically generating, from the reduced volume, by intensity threshold optimization, an optimized intensity threshold and an optimized voxel volume, a color being associated with each intensity, identifying the object by visualization.