a) Chandrayaan-1 Level-1 (CODMAC Level3 ) Products
Current Chandrayaan-1 data sets in this release are Peer Reviewed. The TMC and HySI data sets are based on the latest version of SPICE generated for the full mission except for the period from 14th Nov2008 to 02nd Dec. 2008.
The accuracy of orbit information provided as navigation kernels can vary between 1-20 km. However, user can identify his area of interest on the browse with accuracy better than 1 km (due to the improved corners) for TMC and HySI. But in some cases of HySI it can go up to 20 km. Data losses can be present in a few products, wherein the position of data losses can vary in different bands of HySI. Saturation can be observed in few orbits of HySI. The number of Level-1b HySI products will not match with the number of Level-1a, due to the issues of mis-registration of bands. In some cases of the existing Level-1b products, mis-registration may exist between some bands.
b) Chandrayaan-1 Digital Elevation Models & OrthoImages
Lunar Digital Elevation Model (DEM) are generated from possible passes of Chandrayaan-1 TMC Stereo imagery (around 600+ full passes). Qualitative check (subjective) only has been carried out on all the DEMs., however, the quality flags in the metadata are not available in this version. With respect to some of the available Lunar DEMs in the public domain the planimetric accuracy may vary up to 200 m and DEM height ranges may have some bias. Some height artifacts may exist due to vertical & horizontal spikes, occlusions, shadows, border effects, data losses etc., in the full pass DEM at some places. There may be portions of undefined DEM with values -20000.
In most of the cases, the orthoimage sizes are more than 2GB, hence TIFF 6.0 packed bit compression is used. Only the viewers supporting TIFF 6.0 packed bit compression can display the images. For some of the DEMs, corresponding orthoimages may not be available. The next version is planned to be released in due course with further improvement in accuracies, editing of artifacts, with proper information on quality flags and orthoimages for all the available DEMs.
c) Chandrayaan-1 Lunar Atlas
Composed Lunar Atlas with some of the map sheets are also available in the current release. There could be some discontinuity in the contours and image radiometry because of the mosaic effects of DEMs. The map sheets could be partial and they may have some data losses. Atlas is prepared only for the available TMC covered regions. Spikes due to DEM artifacts could be observed in contours.