In this paper, we discuss different approaches for reducing image noise, including filtering image noise in spatial domain, frequency domain, and time-frequency domain, and estimate their denoising effect. We use a spaceborne SAR (=Synthetic Aperture Radar) image and add several kinds of noise in five different test images under the theoretical concepts of image restoration. They include (1) random noise such as Gaussian noise, speckle noise and salt-and-pepper noise, and (2) systematic noise such as coherent noise. The results demonstrate that Daubechies wavelet approach is efficient. Spatial filters and Daubechies wave-let approach can filter out the Gaussian and speckle noise well. Median filters are good ones for reducing salt-and-pepper noise. Bandreject filters are suitable for filtering out the coherent noise.

The highly repeated observations, multi-temporal or multi-source, of terrain data for a specific area can be often seen due in great part to the purposes of civil activities, topographic monitoring and damage evaluation, etc. They may seem to vary in point density, sampling strategies and accuracy as well, though. From economic point of view, deriving a better estimation of terrain information by fusing the homogeneous terrain data sets may draw great attention both for research and practical interest. As a by-product of that, the topographic change could be also detected accordingly based on the disagreement via fusing procedures. The central principle of fusing terrain data sets stems from cross check, thereby signaling out system­atic problems such as topographic change, among them and keeping steady terrain data sets combined and resulting in an updated terrain data with better accuracy and reliability. The proposed method for fusion of terrain data sets and change detection employs the statistical approach which features in making no as­sumption of the terrain characteristics and without relying on any specific data format. The preliminary results show satisfactory performance based on the evaluations in efficiency and accuracy aspect.

Field experiments were conducted at the experimental farm of Taiwan Agricultural Research Institute, Wufeng, to identify spectral characteristics in associated with chlorophyll concentration in rice leaves and to establish their quantitative relationships. There were 4 rice cultivars grown in the 1st and the 2nd crops of 1998. In leaf optical property, transmittance (t) and reflectance (r) were measured by an external integrating sphere in connected to a spectroradiometer, and absorptance (a) was calculated by a=l-t-r. It was found that 3 wavelengths (664，652 and 644 nm) in the red light region and 1 wavelength (434 nm) in the blue light region were associated with total chlorophyll in rice leaves. The absorptance was positively correlated, while the reflectance was negatively correlated, to the change of total chlorophyll in both cropping seasons. The determining coeffcients (R2) for wavelengths in the red region were greater than that in the blue region, yet the values were cultivar dependent. The relationships between absorptance and reflectance and chlorophyll a and chlorophyll b were also correlated curvilinearly. It was a positive relationship for absorptance and a negative for reflectance. The coefficient of determination for 644 nm was higher than that for 434 nm. Results suggest that optical property of rice leaf may be used to estimate chlorophyll concentration in either cropping season.

A fundamental problem of the unsupervised classification is often the determination of the valid number of the clusters. This study presents a series of testing procedures to investigate the application of a clustering validity function to the fuzzy c-means (FCM) algorithm. The main objective of the investigation is designed to test the performance of the validity criteria for optimal partition. The testing results from a series of remote sensing images indicate that the validity function indeed can be used as the optimal index for the choice of the cluster numbers for the unsupervised fuzzy c-means classification. Moreover, the tests also provide the proper guide for the determination of the applicable range of the fuzziness index.

Traditionally, the color transformation method such as IHS or LAB transformation is usually used as a fusion technique to color higher spatial resolution panchromatic image from lower spatial resolution multi­ spectral image. However the analysis indicates that the success of this image fusion technique depends heavily on a small proportion of spatial resolution between multi-spectral and panchromatic images. For example, a relatively high proportion of spatial resolution will over-resample the image, and consequently smooth down the color variation and feature sharpness of the resultant image. In this study, we develop a segmentation technique to color high spatial resolution panchromatic image. The experiment shows that the proposed approach is able to color EROS panchromatic image (2m resolution) from SPOT multi-spectral composite image (10m resolution) with color and sharpness preserved in the final product.

The goal of this study is by applying NOAA AVHRR data in delineating NDVI maps throughout Taiwan, which can be utilized in the surveys of forested areas. Due to the frequent appearance of clouds, the composite NDVI maps were conducted in a monthly basis where the monthly and seasonal variations of the NDVI values around the mountainous areas were analyzed. The result showed that the total forest area assessed by the NDVI value reached 54.5%. This percentage was rather close to the surveys conducted on the surface, which was 58.5%, proving our procedure to be rather practical.

The author has been chairperson of WG VI/4, International Society for Photogrammetry and Remote Sensing (ISPRS), for 1996-2000, and has been appointed as one of the Editors of ISPRS (http://www.isprs. org/structure/editors.html) for 2000-2004. The author is responsible for Internet of ISPRS and compiling the ISPRS Events Calendar (http://www.isprs.org/calendar.html), which will be published in ISPRS Highlights and placed on the ISPRS home page (http://www.isprs.org). This paper presents the history, presence, and future of the Internet for ISPRS. The Internet and the most known part of it, the World Wide Web, are one of the greatest inventions of our time. The formation and the growth of these big Net has changed the way we do business, communicate, entertain, retrieve information, and even educate ourselves. This worldwide medium allows interaction with people without regard for geographic location and it is a great exchange and source of data, information and software. Inside this electronic world, ISPRS is present since 1994 with the goal of providing information, coordination and operations structure of its activities. In this paper, at first a short history of the WWW is presented, with its main facilities and possibilities. In the second part, after a short introduction on the web site of the society, are presented history, presence, and future plans about the use of Internet by ISPRS, and how ISPRS can make use of existing technologies to improve what it now offered, including the educational strategy. The ISPRS Events Calendar is also introduced.