Color and intensity which are attributes of a point cloud could be effectively used in the feature extraction of a point cloud. Base on the geometrical and spectral characteristics of the flat target

this paper presents a fast flat target extraction algorithm to determine the coordinate of the target center. First

spectral Euclidean distance function is adopted to classify the point cloud based on color information and then a method of color resampling is used to improve the color consistency in the same category. The extraction of the target area is implemented by the values of RGB in terms of the spectral property of the flat target. In addition

the target's validity is confirmed by measuring the area of the extracted circle field. Finally

according to the intensity values of the points

the center of the target area is determined. The feasibility and accuracy of the proposed method are demonstrated by two groups of experiments. The first experiment was conducted by fixing the distance to analyze the extraction accuracy of the center of the target. Comparing with the mean square error of 11.78 mm of the manual extraction method

the mean square error of automatic extraction of the proposed method can reach to 3.31 mm

which is obviously more accurate than the method of manual extraction; and the second experiment involveal an analysis by arranging the targets in different places to get the center coordinates. Through the analysis the following results can be obtained that the extraction accuracy could be better than 2 mm at the distance of 5 m

and be better than 4 mm at the distance of 10 as well as 5 mm at the distance of 15 m

respectively. The feasibility and accuracy of the proposed method are also demonstrated by the experiments conducted in this paper as well.