This paper describes a method for accurately interpolating a low-resolution depth image using a high-resolution color image. In our method, first, tangent planes on each super pixel are estimated from the sparse depth information and dense color information. Then, the neighboring super pixels that have smooth-connectable tangent planes are connected, and the image segmentation to smooth surfaces are achieved. Finally, the low-resolution depth image is interpolated using this smooth surface segmentation. In experiments with images from the Middlebury stereo datasets, our method interpolates each image at a high rate, and achieves the lowest error when compared to existing techniques.