PDS_VERSION_ID = PDS3 OBJECT = SCDATASET DATA_SET_ID = 'MGN-V-RDRS-5-BIDR-FULL-RES-V1.0' OBJECT = DATASETINFO DATA_SET_NAME = 'MGN V RDRS DERIVED BASIC IMAGE DATA RECORD FULL RES V1.0' DATA_SET_COLLECTION_MEMBER_FLG = 'N' START_TIME = 1990-09-16 STOP_TIME = 1994-01-12 NATIVE_START_TIME = 'N/A' NATIVE_STOP_TIME = 'N/A' DATA_OBJECT_TYPE = IMAGE DATA_SET_RELEASE_DATE = 'UNK' PROCESSING_LEVEL_ID = 5 PRODUCER_FULL_NAME = 'DR. RAYMOND E. ARVIDSON' PRODUCER_INSTITUTION_NAME = "WASHINGTON UNIVERSITY" SOFTWARE_FLAG = 'N' DETAILED_CATALOG_FLAG = 'N' PROCESSING_START_TIME = 1990-09-16 PROCESSING_STOP_TIME = 'UNK' DATA_SET_DESC = "Full resolution basic image data records (F-BIDR) consist of SAR (synthetic aperature radar) image data acquired along one orbit. Pixel widths are 75m. Data are presented as 8 bit pixel brightness values where the brightness is in proportion to the scaled radar backscatter cross section. Scaling is accomplished by dividing the radar cross section value for each pixel by the value estimated from the Muhleman Law for the mid range point incidence angle, converting the ratio to decibels, and scaling to a 1 to 251 output range. The 1 value corresponds to -20 dB and 251 to +30 dB, with a linear quantization of 0.2 dB in between. Data have at least 4 looks. Specifically, the scaled radar backscatter cross section is generated by: 1. Dividing the radar cross section by the value obtained from the Muhleman Law. Muhleman Law is alpha * cos(i) sigma0 = --------------------------- (sin(i) + beta * cos(i))**3 where i = incidence angle, and alpha and beta are 0.0118 and 0.111, respectively [Pettengill, et al., JGR, 1988]. (Note: A value of 0.0188 was intended for the multiplicative alpha, but 0.0118 was used by mistake. Also, the incidence angles used to compute the Muhleman Law were systematically low by 0.5 degrees.) 2. Converting to dB by taking 10 times log base 10 of the ratio generated in the first step. 3. Scaling output to a byte DN value using the expression: DN = 1 + INT ({MIN [MAX(RV,-20), 30] + 20} * 5) where RV = value produced in step 2, and INT = nearest integer function. F-BIDRs are presented as image files containing two 2-BYTE VAX integers at the beginning of each line. The first integer specifies the pixel offset to (# bytes to but NOT including) the first valid pixel; the second specifies a pointer to (# bytes to AND including) the last valid pixel. The remainder of the line consists of scaled backscatter cross section values. Regions within 89 degrees of the equator have F-BIDRs in sinusoidal equal area projection; F-BIDR data located more than 80 degrees from the equator are also in oblique sinusoidal equal area projections. For the sinusoidal equal area projection, the origin is at 0 degrees latitude and the central meridian is the sub-spacecraft longitude at the equator, adjusted to the nearest multiple of 75m, relative to a pixel centered at 0 degrees longitude. For details of use of the oblique sinusoidal equal area projection see Magellan Software Interface Specification (SIS) Document by Kon Leung, Full Resolution Basic Image Data Record, SDPS-101, August 1992. The first mapping cycle F-BIDRs extend from the north pole to approximately 52 degrees south latitude for odd-numbered orbits, and from about 55 degrees north latitude to about 79 degrees south latitude for even-numbered orbits. Sinusoidal equal area images sizes are approximately 350 samples by 220,000 lines. Each F-BIDR product is located in a separate subdirectory on this CD-WO. Each product consists of 2 image files and 18 ancillary files for a total of 20 files. In addition, 2 index files, an errata file, and detached PDS labels have been added to assist in the use of the product. Originally, each F-BIDR file was located, together with its ancillary files, on one 6250 BPI 2400 foot 9 track tape. Each F-BIDR consists of approximately 100 million bytes of image data and 40 million bytes of ancillary data. Included in the ancillary files are processing parameters, orbital information, and radar operational information." CONFIDENCE_LEVEL_NOTE = 'UNK' END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = 'VENUS' END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = 'PIXEL' SAMPLING_PARAMETER_RESOLUTION = 0.150 MINIMUM_SAMPLING_PARAMETER = 'N/A' MAXIMUM_SAMPLING_PARAMETER = 'N/A' SAMPLING_PARAMETER_INTERVAL = 0.075 MINIMUM_AVAILABLE_SAMPLING_INT = 'N/A' SAMPLING_PARAMETER_UNIT = 'KILOMETER' DATA_SET_PARAMETER_NAME = 'RADAR SCALED BACKSCATTER CROSS SECTION' NOISE_LEVEL = 'UNK' DATA_SET_PARAMETER_UNIT = 'DIMENSIONLESS' END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = 'MGN' INSTRUMENT_ID = 'RDRS' END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = 'SAUNDERSETAL1992' OBJECT = REFERENCE JOURNAL_NAME = 'JOURNAL OF GEOPHYSICAL RESEARCH' PUBLICATION_DATE = 1992-08-25 REFERENCE_DESC = "Saunders, R.S., et al., Magellan Mission Summary, Journal of Geophysical Research, Vol. 97, No. E8, Pp. 13067-13090, 1992." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = 'R.S. SAUNDERS' END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = 'LEUNG1992' OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = 'SOFTWARE INTERFACE SPECIFICATION' JOURNAL_NAME = 'PROJECT MAGELLAN SIS DOCUMENT' PUBLICATION_DATE = 1992-08-31 REFERENCE_DESC = "Leung, Kon, Full Resolution Basic Image Data Record, Project Magellan Software Interface Specification Document SDPS-101, Jet Propulsion Laboratory, Pasadena, Calif., 1992." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = 'KON LEUNG' END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET END