What are Footprint Product Coverage Maps and how do I use them?
Footprint Product Coverage Maps allow users to see what portion of a planetary surface is covered by all the footprints of all products of a given product type of a given mission and instrument. Each footprint shows an individual product's surface area coverage.
How do I use the Footprint Product Coverage Maps in Google Earth?
How do I use the Footprint Product Coverage Maps Shapefiles?
ODE generates these footprint coverage maps for each product type from each mission/instrument/processing level stored in ODE. For example, Mars ODE provides a map for all MRO HiRISE RDR footprints. The coverage maps show all the footprint coverages for the mission/instrument/processing level/product types. In addition, there are some special coverage maps such as the CRISM TRDR/DDR FRT/HRL/HRS center swath only maps found in the ODE Footprint Coverage Explorer Tool.
There are several versions of each coverage map. KMZ versions can be used in Google Earth. Shapefiles can be used in ESRI’s ArcGIS tools or other GIS tools that support shapefiles.
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Google Earth KMZ Format
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ESRI Shapefile Format
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Global projection with geographic latitude [-90, 90] and longitude [-180, 180]
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Global projection with geographic latitude [-90, 90] and longitude [0, 360]
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Stereographic projection centered at the North Pole
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Stereographic projection centered at the South Pole
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Product Type Derived Footprint File Types |
Description |
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Footprint Product Coverage KMZ Map |
Holds a product coverage map in KMZ form. A coverage map includes the footprints of all products of a given instrument host, instrument, processing level, and product type (identical to ODE’s product search page). All longitudes are in the range -179.999 to 180. The footprints also include a center point. Can be found under the Footprint coverage tool under the Tools tab. |
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Footprint Product Type Shapefile ( Zip or Tar.Gz File) |
Global coverage with geographic coordinates in the range of [-90, 90] latitude and [-180, 180] longitude (“c0x”) |
Holds a product global coverage in Shapefile format with geographic coordinates in the range of [-90, 90] latitude and [-180, 180] longitude. A coverage map includes the footprints of all products of a given instrument host, instrument, processing level, and product type (identical to ODE’s product search page). Can be found under the Footprint coverage tool under the Tools tab. |
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Global coverage with geographic coordinates in the range of [-90, 90] latitude and [0, 360] longitude (“gx”) |
Holds a product global coverage in Shapefile format with geographic coordinates in the range of [-90, 90] latitude and [0, 360] longitude. A coverage map includes the footprints of all products of a given instrument host, instrument, processing level, and product type (identical to ODE’s product search page). Can be found under the Footprint coverage tool under the Tools tab. |
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North hemisphere coverage with Stereographic projection centered at the North Pole (“nx”) |
Holds the North hemisphere coverage map of products in Shapefile format with Stereographic projection centered at the North Pole. A coverage map includes the footprints of all products of a given instrument host, instrument, processing level, and product type (identical to ODE’s product search page). Can be found under the Footprint coverage tool under the Tools tab. |
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South hemisphere coverage with Stereographic projection centered at the South Pole (“sx”) |
Holds the South hemisphere coverage map of products in Shapefile format with Stereographic projection centered at the South Pole. A coverage map includes the footprints of all products of a given instrument host, instrument, processing level, and product type (identical to ODE’s product search page). Can be found under the Footprint coverage tool under the Tools tab. |
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A note about Product Coverage Naming Conventions: Product coverage KML and shapefiles follow the following naming conventions:
KMZ:
Target_InstrumentHostId_InstrumentId_ProductType{_UpperLeftCorner}{_with_time }.kmz
Shapefiles:
Target_InstrumentHostId_InstrumentId_ProductType{_UpperLeftCorner }_type.
(dbf|shp|shx|prj|shp.xml|zip|tar.gz)
There are two types of KMZ coverage files: with or without a time stamp associated with each product. Time stamped products allow users to control what product footprints are displayed based on the observation time. KMZ files with timestamps end with “_with_time”.
In addition to the KMZ coverage files encompassing the entire planet, ODE provides a set of 45x45 degree coverage tiles for the KMZ files. The tiles have their upper left corner in latitude/longitude included in their file names. These tiles are generated by selecting all products with their CENTERS inside the tile. Note: Footprints that cross into a given tile but whose centers are in the neighboring tiles are not included in the given tile. Users should load the neighboring tiles when working close to a tile edge or products with large footprints.
Shapefiles are actually made up of five individual files: .SHP, .SHX, .PRJ, .SHP.XML, and .DBF. To aid in downloading the entire shapefile, the individual shapefile files are provided together in a zip or tar.gz compressed file.
Each shapefile name ends with a type, a character set “_xx” to “_xxxxxx”. The first 1 to 4 characters after the “_” indicate the projection (as shown in the table above “c0”, “g”, “n”. “s”), and the next character indicates the shapefile type (“a”, “l”, “p”).
Shapefiles may only hold points, lines, or areas. Footprint coverage files holding areas have a “_xa” at the end of the name (ex. mercury_messenger_mdis-nac_cdr_cylclon0_c0a). Footprint coverage files holding lines (such as SHARAD RDR’s) have a “_xl” at the end. Footprint coverage files holding points (such as some MESSENGER MDIS products) have an ending of “_xp”. In a few cases such as MESSENGER MDIS products, some products have just center points and some have areas so there are both “_xp” and “_xa” shapefiles.
In most cases, the footprint product coverage will have four shapefiles:
*_g{a|l|p}
*_n{a|l|p}
* _s{a|l|p}
*_c0{a|l|p}
However, in a few cases (example the MESSENGER MDIS datasets), there are both area and point shapefiles. This is because some products have a complete area and some only have a center point.