mdisddr will process a Messenger MDIS NAC or WAC image cube and export it to PDS/DDR format. The resulting file will have a PDS compliant label and data object according to the description in SIS document, mdis_crd_rdrsis.pdf. This file can be found in the PDS data archive CDROM under the document directory. mdisddr assumes the input file has been run through at a minimum mdis2isis and spiceinit. This will ensure that proper values of the PRODUCT_ID and SOURCE_PRODUCT_ID are included in the output DDR label.

The Derived Data Record (DDR) data set consists of files that parallel CDRs in their directory structure. Each DDR has 5 layers of data containing geometric information (latitude, longitude, incidence angle, emission angle, phase angle) as 32-bit PC_REAL or IEEE_REAL. This information is derived from pixel spatial coordinates and associated SPICE files. A DDR label is attached and points to a single multiband image in the DDR. x, y dimensions = 1024/(MESS:FPU_BIN * MESS:PIXELBIN)

The sequence of processing that creates a DDR is as follows. Gimbal positions are extracted from the gimbal C kernel. Using that and other SPICE kernels, the equipotential surface intercept is calculated for each spatial pixel. The angles of this pixel relative to the equatorial plane and reference longitude constitute the latitude and longitude of the pixel. For that latitude and longitude, solar incidence, emission, and phase angles are determined. This is the order in which the bands are written to the output PDS image file.