Navcam data sets

Data Set Overview

This data set contains data that is used to assess the morphology, topography, and geologic context of each rover site, to determine surface photometric properties, and to constrain aerosol physical and radiative properties. The calibration has removed bias, dark current, and flatfield effects from the raw Navcam EDRs and resulted in the generation of estimated radiance-on-sensor data from Navcam, in units of W/m^2/nm/sr. No geometric or camera-model calibrations or transformations have been applied. For details, see Soderblom, J.M., J.F. Bell III, J.R. Johnson, J. Joseph, and M.J. Wolff (2008) Mars Exploration Rover Navigation Camera (Navcam) in-flight calibration, J. Geophys. Res., 113, E06S19, doi:10.1029/2007JE003003, a PDF of which is distributed with the PDS archive.

Processing

MER Camera Payload RDRs are considered Level 3 (Calibrated Data equivalent to NASA Level 1-A), Level 4 (Resampled Data equivalent to NASA Level 1-B), or Level 5 (Derived Data equivalent to NASA Level 1-C, 2 or 3). The RDRs are reconstructed from Level 2 edited data, and are assembled into complete images that may include radiometric and/or geometric correction.

MER Camera Payload EDRs and RDRs are generated by JPL's Multimission Image Processing Laboratory (MIPL) under the OPGS subsystem of the MER GDS. RDRs are also generated by the Athena Pancam Science and Microscopic Imager Science Teams under the SOAS subsystem of the GDS.

RDR data products are generated by, but not limited to, MIPL using the Mars Suite of VICAR image processing software at JPL, the Athena Pancam Science Team using IDL software at Cornell University and JPL, and the Microscopic Imager Science Team using ISIS software at USGS (Flagstaff) and JPL. The RDRs produced are processed data. The input is one or more Camera EDR or RDR data products and the output is formatted according to the MER Camera EDR/RDR SIS. Additional meta-data may be added by the software to the PDS label.

There may be multiple versions of MER Camera RDRs.

Data

RDR products generated by MIPL have a VICAR label wrapped by a PDS label, and their structure can include the optional EOL label after the binary data. RDR products not generated by MIPL may contain only a PDS label. Or, RDR products conforming to a standard other than PDS, such as JPEG compressed or certain Terrain products, are acceptable without a PDS header during mission operations, but may not be archivable.

The RDR data product is comprised of radiometrically decalibrated and/or camera model corrected and/or geometrically altered versions of the raw camera data, in both single and multi-frame (mosaic) form. Most RDR data products have PDS labels, or if generated by MIPL (OPGS), dual PDS/VICAR labels. Non-labeled RDRs include JPEG compressed products and the Terrain products.

Software

MER Camera Payload downlink processing software is focused on rapid reduction, calibration, and visualization of images in order to make discoveries, to accurately and expeditiously characterize the geologic environment around the rover, and to provide timely input for operational decisions concerning rover navigation and Instrument Deployment Device (IDD) target selection. Key software tools have been developed at Cornell University, at JPL by the MIPL, SSV, and APSS groups, at NASA Ames, and at the USGS/Flagstaff. These tools can also be used to process MI images (see below), as well as Navcam and Hazcam images, which have substantial scientific potential in addition to their operational importance.

PDS-labeled images and tables can be viewed with the program NASAView, developed by the PDS and available for a variety of computer platforms from the PDS web site. There is no charge for NASAView.

Confidence Level Note

See SODERBLOMETAL2008 for a description of Navcam in-flight calibration. The authors estimate that their absolute radiometric calibration has an absolute accuracy of 10% and a relative precision of 2.5%. The calibration pipeline includes steps to model and remove the bias offset, the dark current charge that accumulates in both the active and readout regions of the CCD, and the shutter smear. It also corrects pixel-to-pixel responsivity variations using flat-field images.

Data Set Overview

This data set contains images acquired by the Navcams for the support of rover traverse planning, post-traverse assessment, rover localization, operation of the instrument arm, and the selection of science targets. Most Navcam images were commanded via ground commands from Earth, although a subset of Navcam images were commanded autonomously during rover traverses by the Rover on board autonomous navigation system. The Navcams were extensively used to acquire end of drive 360-degree panoramas. These panoramas served as the primary set of data from which Pancam and Mini-TES targets were chosen from. The Navcam panoramas were also extensively used for rover traverse planning and generally cover more of the local Martian surface terrain than the Pancam or Hazcam cameras.

Processing

This data set uses the Committee on Data Management and Computation (CODMAC) data level numbering system. The MER Camera Payload EDRs are considered Level 2 or Edited Data (equivalent to NASA Level 0). The EDRs are reconstructed from Level 1 or Raw Data, which are the telemetry packets within the project specific Standard Formatted Data Unit (SFDU) record. They are to be assembled into complete images, but are not radiometrically or geometrically corrected.

Hazcam EDR data products were generated by the Multi-mission Image Processing Lab at the Jet Propulsion Laboratory using the telemetry processing software mertelemproc. The EDRs produced are raw uncalibrated data reconstructed from telemetry packet SFDUs and formatted according to the Camera EDR/RDR Software Interface Specification. Meta-data acquired from the telemetry data headers and a meta-data database were used to populate the PDS label. There will not be multiple versions of a MER Camera Payload EDR. Missing packets will be identified and reported for retransmission to the ground as partial data sets.

Data

1. Full Frame EDR: Full Frame EDRs are stored as 16-bit signed integers. If 12-to-8 bit scaling is performed, then pixels are stored in 16-bit format and only the last 8 bits of the 16-bit integer are used.
2. Thumbnail EDR: Thumbnail EDRs are stored as 16-bit signed integers or 8-bit unsigned integers. If 12-to-8 bit scaling is performed, then pixels are stored in 16-bit format and only the last 8 bits of the 16- bit integer are used. The Thumbnail EDR is a spatially downsampled version of the original acquired source image (all EDRs for a particular image are derive from the same source image). For example, in the case of subframe image products the thumbnail image represents the full-frame contextual image form which the subframe image data was extracted from. Note that the original acquired image is not always downlinked, and in some cases thumbnails are the only returned data for a particular observation. The main purposes of a Thumbnail EDR are to provide image previews and contextual information, both at a very low data volume compared to the original image.
3. Sub-frame: EDR Sub-frame EDRs are a subset of rows and columns of the 1024 x 1024 full frame image. Sub-frame EDRs are stored as 16-bit signed integers. If 12-to-8 bit scaling is performed, then pixels are stored in 16-bit format and only the last 8 bits of the 16-bit integer are used.
4. Downsampled EDR: A downsampled EDR is a smaller version of the 1024 x 1024 full frame or subframed image using the following methods:
   1. nearest neighbor pixel averaging,
   2. pixel averaging with outlier rejection or
   3. computing the median pixel value. Downsampled EDRs are stored as 16-bit signed integers. If 12-to-8 bit scaling is performed, then pixels are stored in 16-bit format and only the last 8 bits of the 16-bit integer are used.

Software

MER Camera Payload downlink processing software is focused on rapid reduction, calibration, and visualization of images in order to make discoveries, to accurately and expeditiously characterize the geologic environment around the rover, and to provide timely input for operational decisions concerning rover navigation and Instrument Deployment Device (IDD) target selection. Key software tools have been developed at JPL by the Multimission Image Processing Laboratory (MIPL). These tools were also used to process Pancam and MI images.

PDS-labeled images and tables can be viewed with the program NASAView, developed by the PDS and available for a variety of computer platforms from the PDS web site. There is no charge for NASAView.

Media/ Format

The data set will initially be delivered and kept online. Upon Mission completion, the Hazard Avoidance Camera EDRs will be delivered to PDS on DVD as part of the complete MER EDR data set.