Off-nadir viewing effects in High resolution Data

Small swath and coarse temporal resolution are the major limitations of high resolution satellite sensors for applications like monitoring large areas within limited period of time interval. In general, higher the spatial resolution smaller is the swath and coarser is the temporal resolution. In order to overcome this constraint, sensors are equipped with the capability to tilt from nominal nadir viewing to the required direction. When user specified area is difficult to acquire using Nadir viewing, Off-nadir viewing is exercised by tilting the platform/sensor to the required area.A study was carried out on off-nadir viewing effects in terms of radiometry and geometry using high resolution data. The parameters considered were (a) quality of resultant mosaic images (b) variations in the spatial resolutions (c) variations in the radiometry from the images acquired with various amount of tilts over different types of terrains. This paper aims to bring out the effects on the geometric and radiometric data quality and usability of value-added products generated from off-nadir high resolution data by analyzing existing IRS-Carto2S data. The observations drawn are useful for operating future IRS HR satellites to supply high quality products to the user community.