|
FME Format Type Identifier |
BAG |
|
Reader/Writer |
Both |
|
Typical File Extensions |
.bag |
Bathymetric Attributed Grid (BAG) is a file format developed by the Open Navigation Surface Working Group for storing and exchanging bathymetric data.
A BAG raster contains two bands:
- The first band contains elevations. The units of the elevation values are meters, and the sign convention is that positive values represent measures above the vertical datum.
- The second band describes the vertical uncertainty at each point of elevation. The uncertainty grid supports multiple definitions of uncertainty; the metadata contains information on the meaning of the uncertainty grid.
A BAG file also contains metadata describing who, what, when, where, and how the file was created. This is stored as XML conforming to the ISO 19115 specification. See the bag_metadata_string attribute documentation.
Another component of a BAG file is the tracking list. This list details hydrographer modifications. It is a simple list of original elevation and uncertainty values that have been modified to account for over-rides of the basic surface definition (for example, as originally computed by an algorithmic method). The tracking list and corresponding information in the metadata provide an audit trail of changes made to the data. See the bag_tracking_list list attribute documentation.
BAG Product and System Requirements
|
Format |
FME Platform |
Operating System |
||||
|---|---|---|---|---|---|---|
|
Reader/Writer |
FME Form |
FME Flow |
FME Flow Hosted |
Windows 64-bit |
Linux |
Mac |
|
Reader |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
|
Writer |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Reader Overview
FME considers a single BAG file to be a dataset. Each dataset contains a single FME raster feature.
Writer Overview
FME considers a dataset to be a folder name. The feature type of each dataset is the filename. The BAG writer distinguishes duplicate output files by appending numbers to the filenames.
FME Raster Features
FME raster features represent raster data and use several concepts that are unlike those used in the handling of vector data.
For comprehensive information about how FME processes raster data, see Rasters.
BAG only supports rasters with exactly two numeric bands.