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This paper reports results on the LAI Retrieval and Validation Experiment (LRVE) that was conducted for two agricultural areas in Central India during the winter season of 2001–2002. The study aimed at relating field measurements of leaf area index (LAI) to spaceborne Indian Remote Sensing Satellite (IRS) Linear Imaging Self Scanning Sensor-III (LISS-III) data, preparation of site-level LAI maps, and validation of Moderate Resolution Imaging Spectroradiometer (MODIS) 1-km LAI global fields. Measurements of field-level LAI, aerosol optical thickness and water vapor were carried out on the day of LISS-III overpasses. Empirical models based on the site-specific LAI-vegetation index relation were developed and used to generate 23-m resolution LAI maps for two sites (Indore and Bhopal) covering 30 km × 30 km. These LAI images were degraded to 1-km spatial resolution and used for validation of the version 3 and 4 MODIS LAI products (MOD15A2). The results indicate a positive correlation (r = 0.78) between LAI derived from LISS-III data and MODIS data. However an overestimate by a factor of 1.6 to 2.5 in the version 3 MODIS product is observed with root mean square error (RMSE) ranging from 0.20 to 1.26. The factor of overestimation reduces significantly by 50% and RMSE by 40% when version 4 MODIS LAI was analyzed. The improvement in accuracy was observed to be associated with the change in algorithm path adopted for retrieving version 3 and 4 MODIS LAI. Analysis of the MODIS land cover product that is an input in the MODIS LAI retrieval algorithm indicated errors in assigning land cover classes for the study sites, which could be one of the sources of error in MODIS LAI product. [ABSTRACT FROM AUTHOR]

We propose to use multiple-description coding (MDC) to protect video information against packet losses and delay, while also ensuring that it can be decoded using a standard decoder. Video data are encoded into a high-resolution stream using a standard compliant encoder. In addition, a low-resolution stream is generated by duplicating the relevant information (motion vectors, headers and some of the DCT coefficient) from the high-resolution stream while the remaining coefficients are set to zero. Both streams are independently decodable by a standard decoder. However, only in case of losses in the high resolution description, the corresponding information from the low resolution stream is decoded, else the received high resolution description is decoded. The main contribution of this paper is an optimization algorithm which, given the loss ratio, allocates bits to both descriptions and selects the right number of coefficients to duplicate in the low-resolution stream so as to minimize the expected distortion at the decoder end. [ABSTRACT FROM AUTHOR]