Magellan Global Topography 4641m
This product has been superseded by Magellan Global Topography 4641m v02 (1997).
Global Topographic Data Record (GTDR). The range to surface is derived by fitting altimeter echoes from the fan-beam altimetry antenna as a function of time to Hagfors' radar backscatter model templates. The ranges are subtracted from the spacecraft radial coordinate (derived from Doppler tracking), yielding measurements of planetary radius. The data were filtered to remove low-frequency errors in the in-plane elements of each spacecraft orbit, and then originally re-sampled into sinusoidal, Mercator, and north and south polar stereographic projections at a resolution of about 5 kilometers per pixel.
A fifth image was originally produced that contains estimates of the absolute error of the radius values in each pixel of the sinusoidal projection. This is derived by taking the root mean square of (a) the statistical accuracy anticipated from the template fitting and (b) the systematic errors estimated from the in-plane element filtration. Note that this is the absolute topographic accuracy -- relative errors are much smaller, about 10-15 meters in relatively flat areas. A global mosaic of this error map in sinusoidal projection is available under the "Ancillary Products" section on the right side of this page.
Each GTDR pixel is represented by a 16-bit integer. Pixels lying outside the domain of the projection are set to NoData (-32678). In all images, pixels with unknown or unmeasured values are also set to NoData . The remaining values have been processed into elevations with a data range of -2990 to 11520 meters.
To return these values from elevation back to radius values use the following equation: Radius = DN + 6051000.0
Ref: Software Interface Specification Document (Peter G. Ford, 1991, Global Altimetry and Radiometry Data Records, MIT-MGN-GxDR SIS Version 2.3, 40 p.) that is included on GxDR CD-ROMs. Note: There exist photoproducts that are identified as GxDRP (where x is E (Emissivity), S (Slope), RE (Reflectivity), or T (Topography)) however, they are not generated from the digital GxDR products. They are instead produced from the Magellan ARCDR (Altimetry and Radiometry Composite Data Record) data files.
- Publisher
- PDS GeoScience Node
- Author
- Magellan Team
- Originator
- Peter Ford, Gordon Pettengill, Fang Liu, Joan Quigley
- Group
- Astrogeology
- Added to Astropedia
- 14 March 2014
- Modified
- 23 May 2017
General
- Purpose
Topographic elevation in meters as collected from Magellan altimetry.
- Geospatial Data Presentation Form
- Digital Elevation Model, Topographic Map, Remote-sensing Data
- Edition
- 1
- Online Linkage
- https://planetarymaps.usgs.gov/mosaic/Venus_Magellan_Topography_Global_4641m.tif
- Native Data Set Environment
- ISIS v3
- Supplemental Information
- http://pds-geosciences.wustl.edu/mgn/mgn-v-gxdr-v1/mg_3002/gtdr/, http://pds-imaging.jpl.nasa.gov/portal/magellan_mission.html
Keywords
- Target
- Venus
- Theme
- Topography
- Mission
- Magellan
- Instrument
- SAR
Contact and Distribution
- Access Constraints
- public domain
- Use Constraints
- Please cite authors
Data Status and Quality
- Currentness Reference
- Publication date
- Progress
- Complete
- Update Frequency
- None planned
- Process Date
- 23 June 1993
- Process Description
The original PDS release was map projected to Simple Cylindrical and the offset and scaler were applied to return elevation values with the range from -2990 to 11520.
This archive was produced by Jason Hyon. Mike Martin (JPL), Gail Woodward (JPL), Peter Ford (MIT), Robert Mehlman (UCLA), and Jason Hyon (JPL) designed the PDS labels and the tables. Florence Moss (JPL) and Jason Hyon developed the software to generate the PDS labels and tables. Raymond Arvidson and Gail Woodward created the catalog templates, with help from Pam Woncik (JPL), Mary Dale-Bannister (Washington University), and Susan Slavney (Washington University). The data and documentation were generated at MIT by Peter Ford, Gordon Pettengill, Fang Liu, and Joan Quigley from data supplied by the Magellan Project. Please direct any questions and comments to the PDS Geosciences Node, geosci@wunder.wustl.edu.
- Entity and Attribute Detailed Description
- DN = elevation (m); RADIUS = DN + 6051000.0
- Entity and Attribute Linkage
- http://pds-geosciences.wustl.edu/missions/magellan/gxdr/
Lineage
- Source Originator
- PDS Geosciences Node
- Source Publication Date
- 23 June 1993
- Source Title
- Magellan Global Topography, Emissivity, Reflectivity, and Slope Data Record (GXDR)
- Source Online Linkage
- http://pds-geosciences.wustl.edu/missions/magellan/gxdr/
- Type of Source Media
- Online
Geospatial Information
- Minimum Latitude
- -90
- Maximum Latitude
- 90
- Minimum Longitude
- -180
- Maximum Longitude
- 180
- Direct Spatial Reference Method
- Raster
- Object Type
- Pixel
- Lines (pixels)
- 4097
- Samples (pixels)
- 8193
- Bit Type
- 16
- Quad Name
- Radius A
- 6051000
- Radius C
- 6051000
- Bands
- 1
- Pixel Resolution (meters/pixel)
- 4641.0588
- Scale (pixels/degree)
- 22.755555917149
- Horizontal Coordinate System Units
- Meters
- Map Projection Name
- Simple Cylindrical
- Latitude Type
- Planetocentric
- Longitude Direction
- Positive East
- Longitude Domain
- -180 to 180