Publications (6)0 Total impact
-
Conference Proceeding: Continental scale land cover classification using MODIS surface reflectance products.
2011 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2011, Vancouver, BC, Canada, July 24-29, 2011; 01/2011 -
Article: Evaluations of unsupervised methods for land‐cover/use classifications of landsat TM data
Geocarto International 06/1988; 3(2):37-44. -
Article: Complete Lineament Extraction with the Aid of Shadow-Free LANDSAT Image
[show abstract] [hide abstract]
ABSTRACT: LANDSAT images are most useful for geological lineament extraction, especially for large-scale lineaments. However, because of the nature of the LANDSAT orbit, there are almost no lineaments in the same direction as the sun angle. In this report, a new technique which can generate virtual LANDSAT images with any sun directions is described.In order to eliminate shadows from the original LANDSAT image, a shadow-free land cover classification was first applied. Shadow areas were classified into four categories using spectral features. Pixel values in each categories of the original image were scaled to the values of corresponding categories in no-shadow areas, by coinciding the mean and standard deviation of each spectral bands.Next, a three-dimensional model of the object area was constructed from the National Land Information Data Base. Assuming a specific sun elevation and azimuth, the shadowed areas can be calculated from this model.A cosine correction was made using the angle between the sun light axis and the plane direction. In addition, reflective intensities were calculated according to a three dimensional reflective model. An artificially shadowed LANDSAT image with specific sun angle was thus obtained.For lineament extraction, a sun azimuth was selected perpendicular to the real sun azimuth. A complete set of lineaments was obtained by combining the two results extracted from these two images. Furthermore, the influence of sun elevation on lineament enhancements is also discussed.In conclusion, a technique to generate a virtual LANDSAT image with illumination at any sun angle was established. with the aid of this virtual image, lineament extraction becomes more complete.LARS Symposia. -
Article: A Development of Interactive Image Processing Software System TIPE
[show abstract] [hide abstract]
ABSTRACT: Conventional monitors of image processing systems have not sufficient flexibility, expandability and easy-handing capability.TIPE has been developed to overcome these problems. The monitor of TIPE consists of following three subsystems(1) A scheduling system including a scheduler and menu files.(2) A control parameter management system including a control parameter management module and control parameter files.(3) A catalog system including a catalog management module, catalog files and a header management module.Scheduling system is based upon menu files which are hierarchicaly organized. In the control parameter management system, control parameters are stored in a disc file called a control parameter file. When a series of program is repeatedly scheduled, TIPE user need not to input most of these parameters and can select a proper control parameter file.TIPE maintains digital image informations in a form called TSF (TRIC Standard Format). The catalog system and the TSF establish an image data base that allows the system to maintain the image files automatically.With the configuration of TIPE described above, the great deal of flexibility and expandability were achieved. Furthermore, easy-handling capability was achieved by providing an image data base concept and the control parameter system.LARS Symposia. -
Article: Quantitative analysis of image quality of lossy compression images
[show abstract] [hide abstract]
ABSTRACT: High resolution images acquired by an aerial digital camera and high resolution satellite images are expected to become more powerful data source of GIS. Since the large data volume of a high resolution image brings difficulties in dealing with it, lossy image compression is going to be indispensable. Image quality of a reconstructed image after decompression is usually evaluated by visual inspection. Although some numerical measures such as RMSE or PSNR are used to compare various image compression techniques, numerical evaluation of quality of a reconstructed image is seldom conducted. Therefore, we decided to carry out an empirical investigation into the effects of lossy image compression on quality of color aerial images by using color and texture measures. From the experiment results, it can be concluded that color space conversion and downsampling in JPEG compression have an effect on quality of a reconstructed image. The results supported that lossy JPEG 2000 compression is superior to lossy JPEG compression in color features. However, lossy JPEG 2000 compression does not necessarily provide an image of good quality in texture features. Moreover, the results indicated that an image of finer texture features is less compressible, and quality of the reconstructed image is worse in both color and texture features. Finally, it was confirmed that it is difficult to set an appropriate the quality factor, because the optimal setting of the quality factor varies from one image to another. -
Article: Numerical Simulation on Evaluating Calibration Results of Non-Metric Digital Camera
[show abstract] [hide abstract]
ABSTRACT: A non-metric digital camera is required to be geometrically calibrated when it is used for photogrammetric applications. Many camera calibration methods for a non-metric digital camera have been proposed. However there is no standard procedure to evaluate an estimated image distortion model directly. Calibration results are usually evaluated indirectly by such indexes as residuals on image, three-dimensional measurement errors of control points, and error estimates of obtained camera parameters. Therefore, we conducted a numerical simulation in order to examine capabilities of these indexes. In the simulation nine images were supposed to be acquired vertically to shoot 1024 control points on four layers disposed at regular intervals of the depth. Seven sets of 1024 control points were prepared, and these sets varied in the depth of the distribution of control points from 2/3 to 1/96 of the average camera height. In the simulation 49 cases with different sets of control points and different precision of image coordinates were investigated. Numerical simulation results show the limits of capabilities of these indexes. A larger value of one of these indexes obtained in a camera calibration usually means that the image distortion model estimated by the calibration is not reasonable. On the other hand, smaller values of all of these indexes do not always mean that the estimated image distortion model is appropriate. Thus the authors propose that a set of the prior and posterior numerical simulations should be conducted in a camera calibration to evaluate calibration results in addition to conventional evaluation by using the abovementioned indexes.
