The linear array 3D imaging sensor uses a common optical path system to acquire image and point cloud data at the same time. The registration of these two types of data is realized by the common optical axis alignment and time synchronous control system. Since the image and point cloud data have different sampling frequencies; the process of generating colored point cloud needs to interpolate the point cloud. According to the principle of IDW method and the characteristics of the data acquired by the linear array 3D imaging sensor, this article proposes an improved IDW method by selecting the power parameter adaptive to the topography and designing a topographic factor in the weight calculating. The experiment results show that the improved IDW method improves the interpolation accuracy.