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In this we propose an algorithm to automatically find objects in 3D Flash Lidar images. Three-dimensional Flash Lidar camera is a new technology which allows a single camera to take multiple images in a fast succession. It produces a series of range delimited imagery using a single laser flash. The imagery can distinguish between objects at different distances, such as the sea-surface and underwater objects. We apply a transformation to reduce the computational complexity and apply stable unsupervised multiphase segmentation for object identification. Numerical results are presented to validate the approach both using scalar and Victor models. Key words -Flash Lidar, segmentation, Classification, frequency coefficients 1.IntroductionThree-dimensional Flash Lidar imaging represents one of the latest advances in imaging technology [18] which uses a single laser pulse to generate a threedimensional data. 3D Flash Lidar camera uses smart pixels for signal integrators: each pixel can accurately and independently count time to the target. The light reflected from a certain distance is captured in a plane of the image volume in a fast succession. This imagery is different from the typical LIDAR (Light Detecting and Ranging) images, where several laser pulses are used to record the distance to the surface or objects. LIDAR has many applications in environmental and civil engineering and it is widely used for forestry, building constructions, and ground surface modeling as in [4,7,11,14]. There are many references for LIDAR images, while 3D Flash Lidar image is a new approach. 3D Flash Lidar images capture the luminance of each distance, then produce a succession of 2D images at particular distances from the camera, that 3D Flash Lidar images have very different characteristics compared to LIDAR images. One of the challenges of 3D Flash Lidar images comes from the images taken from a moving vehicle. For example, when the images are taken from an airborne vehicle, one object can be captured in few different 2D images each from a different distance from the camera. Figure 1 shows an example of 3D Flash Lidar image, a partial sequence of images taken from an airborne vehicle. The plane (a) depicts objects closer to the camera, and image (b) through (h) successively farther. Notice, the glint from the water surface begins in plane (b). The submerged object comes into view beginning with plane (f), then it is clearly visible in (g). It is evident that the airplane is not parallel to the water, since the glint first appears on the right side of the planes but disappears on the left.