We present a three-dimensional imaging method using a pulsed laser as a flood illuminating source and an intensified camera as the receiver with exponentially modulated gain. The depth map of a scene is obtained from two intensity images and the depth accuracy is independent of the depth of the target in the scene. We demonstrate a depth-independent depth accuracy of 0.32 m in an indoor experiment and obtain a depth map of an outdoor scene ranging from 150 to 180 m under a lower signal to noise ratio condition.