PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM SPACECRAFT_NAME = "CLEMENTINE 1" TARGET_NAME = MOON OBJECT = DATA_SET DATA_SET_ID = "CLEM1-L-H-5-DIM-MOSAIC-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "CLEMENTINE HIRES MOSAIC" DATA_SET_COLLECTION_MEMBER_FLG = "N" START_TIME = "N/A" STOP_TIME = "N/A" DATA_SET_RELEASE_DATE = 1998-09-12 PRODUCER_FULL_NAME = "DR. MICHAEL C. MALIN" DETAILED_CATALOG_FLAG = "N" DATA_OBJECT_TYPE = "IMAGE" DATA_SET_DESC = " Data Set Overview ================= This CD contains portions of the Clementine HiRes Lunar Mosaic, a geometrically controlled, calibrated mosaic compiled from non-uniformity corrected, 750 nanometer ('D') filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics cover sub-polar regions between 80 deg S and 80 deg N with the sinusoidal equal area mapping at 20 m/pixel, and the polar regions above 80 deg with a stereographic mapping at 30 m/pixel resolution at the poles. The geometric control is provided by the 100 m/pixel USGS Clementine Basemap Mosaic (PDS CD-ROM Volumes CL_3001-3015) compiled from the 750 nm Ultraviolet/Visible Clementine imaging system and, for the polar mosaics, from the 150 m/pixel polar basemap mosaic. Calibration was achieved by removing image nonuniformity largely due to the HiRes system's light intensifier. Also provided are offset and scale factors which transform the 8-bit HiRes data to approximate photometric units, achieved by a fit of the HiRes data to the corresponding UV/Vis basemap, which is photometrically calibrated. The mosaic on this CD covers polar regions above 80 degrees. The mosaics are divided into square tiles 2250 pixels on a side, which spans approximately 2.2 degrees. This CD also contains ancillary data files that support the HiRes Mosaic. These files include browse images with UV/Vis context stored in a JPEG format, HTML documents that support a web browser interface to the CDs, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the 'FILES, DIRECTORIES AND DISK CONTENTS' section of this document. Using a web browser open the 'index.htm' file located in the 'root' directory of the CD. The html document will direct you to other informational documents and the image browser for rapidly viewing the image collection. Parameters ========== N/A Processing ========== Processing proceeded an orbital and latitude 'bin' basis, reflecting the organization of the Clementine EDR CDs. A latitude bin comprises all images of a given orbit deemed to fall within a 10 degree latitude range based on SPICE information. The latitude ranges are defined to fall on on 10-degree boundaries from -90 to +90. For the sub-polar mosaics, map projection of images from a given orbit used the same central longitude, taken to be the orbit's longitude at the lunar equator. Images used in the polar mosaics were warped to a common stereographic projection relative to the pertinent pole. The HiRes Mosaic processing comprised 5 steps: (1) Image calibration, map project and basemap generation; (2) Low resolution registration against the UV/Vis basemap; (3) High resolution registration against overlapping images; (4) Constrained placement combining high- and low-resolution registrations; and (5) HiRes mosaic and photometric calibration estimation. Placement and calibration for the polar mosaics differed in some regards from those of the sub-polar mosaics. Due to illumination paucity, various polar locales lacked useful geometric and photometric control. In these regions, registration between individual HiRes frames, both with and among orbits, was the primary placement guide. Such placement was anchored to images which did have reliable registration against the UV/Vis basemap. For convenience, rectangular zones centered on the poles were defined within which placement proceeded in this manner. Similarly, the basemap photometric calibration was considered unreliable at the highest latitudes, and so for a given HiRes polar mosaic, a single calibration (based on well-illuminated tiles and basemap portions) was adopted for the entire mosaic, rather than defining one for each individual tile. Media/Format ============ The Clementine basemap is delivered to the Planetary Data System using CD media. Formats are based on standards for such products established by the Planetary Data System (PDS) [PDSSR1992]. " CONFIDENCE_LEVEL_NOTE = " ===================== Geometric Accuracy ------------------ The geometric placement of the HiRes Mosaics is based primarily onregistration with the Clementine Basemap Mosaic, which has accuracies approaching the UV/Vis scale. The UV/Vis accuracy is discussed below, drawing extensively from the UV/Vis Basemap Mosaic documents. The goal of the UV/Vis basemap was for 95% of the Moon (excluding the oblique observation gap fills) to have better than 0.5 km/pixel absolute positional accuracy and to adjust the camera angles so that all frames match neighboring frames to within an accuracy of 2 pixels. Approximately 265,000 match points were collected at the USGS from ~43,000 UV/Vis images, providing global coverage. About 80% of these points were collected via autonomous procedures, whereas the 20% required the more time consuming but highly accurate manual pattern-recognition. The oblique gap-fill images were the most difficult to match, and required substantial human intervention. Matching the polar regions was time-consuming because each frame overlaps many other frames. Most match points were found to a precision of 0.2 pixels. The USGS match points were sent to RAND corporation for analytical triangulations. Using these match points, control points from the Apollo region, and the latest NAIF/SPICE information, RAND determined improved camera orientation angles for the global set of UV/Vis images. A spherical Moon of constant radius (1737.4 kilometers) was assumed, which was a significant source of error near the oblique gap fills. The analytical triangulation is a least-squares formulation designed to adjust the latitude and longitude of the control points and the camera orientation angles to best fit the match points. The final (global) analytical triangulation required solving ~660,000 normal equations. The mean error is less than 1 pixel. This is by far the largest analytical triangulation ever applied to a planetary body other than Earth. The results fully define the planimetric geometry of the basemap, to which future systematic products, such as the present HiRes Mosaic, should be tied. Accurate placement of the map-projected HiRes images was accomplished by combining registration to the UV/Vis basemap at the basemap's resolution (100 m/pixel and 150 m/pixel) with registration of overlapping HiRes pairs at five times this resolution (20 m/pixel and 30 m/pixel). The registrations were facilitated with automated image correlation. These registrations were combined in a Least Absolute Deviation fit [BARRODALE1980] constrained to stray no further than some small amount from the basemap-scale registration. Use of the least absolute deviation gives outliers less importance than does a least squares fit. Further manual placement of 1-5 percent of the image was required; these were due either to poor initial placement, particularly when the scene was featureless and provided few or no overlapping features with the UV/Vis basemap, or to mismatches of scene, resolution or illumination across seams in the UV/Vis mosaic. Some misregistration of adjacent HiRes images remains in the final mosaic because the paramount goal was registration with the underlying UV/Vis Basemap Mosaic. As described above, the HiRes polar mosaics lacked Uv/Vis basemap registration in shadowed regions, most notably at and immediately adjacent to the poles. In such locales, the placment of HiRes images was guided primarily by registration of individual HiRes frames within and among orbits. Such placement was applied within approximately 2 degrees of the poles. Radiometric Units ================= To date, absolute photometric calibration of the HiRes image data remains elusive. This seems particularly problematic for the bulk of HiRes images, which were noisy due to the low gain setting intended to extend the lifetime of the imaging system. For these reasons, a piece-wise intensity matching of the HiRes Mosaics to the UV/Vis Basemap Mosaic was adopted as an approximate radiometric calibration. The further decision was made to use 750 nm ('D') filter HiRes images in order to best match the UV/Vis Basemap Mosaic, which dominantly comprises 750 nm ('B') filter images. A more detailed description of the UV/Vis basemap photometric calibration may be found on the UV/Vis basemap volumes CL_30XX. Whereas sub-polar HiRes tiles were individually calibrated against the underlying UV/Vis basemap, each of the four HiRes polar mosaics have a single calibration for all tiles. This is due to the difficulties associated with calibrating regions perennially in shadow, which renders some portions of the underlying polar basemap calibration unreliable. To mitigate this problem, a well- illuminated tile and basemap portion near 85 deg latitude from each mosaic was adopted as calibration references. This calibration is embodied by the header values of the OFFSET and SCALING_FACTOR entries, which defines HiRes fractional reflectances: HIRES MOSAIC FRACTIONAL_REFLECTANCE = (SCALING_FACTOR * DN) + OFFSET where: DN = 8-bit pixel value of HiRes mosaic image array. SCALING_FACTOR units are fractional reflectance per DN OFFSET units are fractional reflectance The calibration in every case included correction for the non-uniformity of the raw HiRes images due to the light intensifier." END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = MOON END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = CLEM1 INSTRUMENT_ID = HIRES END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PDSSR1992" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END