4. Output SRS definition is metadata for output positions 5. Absolute accuracy estimates for output position coordinates is metadata for output positions
6. Relative accuracy estimates for output position coordinates is metadata for output positions Note: Result metadata is optionally returned to client software, depending on how the service is
called. Similarly, partial derivatives are optionally returned to client software. The ability to produce result metadata and partial derivatives when requested are required capabilities of this
service category.
3.1.4. Needed data
The data needed by these services input data includes, but are not limited to, the following: 1. Input ground position coordinates, in another SRS
2. Output SRS definition is metadata for output positions 3. Coordinate transformation parameters optional is metadata for SRS or transformation
4. Transformation accuracy estimates, for each SRS transformation when output accuracy is needed
is metadata for transformation 5. Metadata for input position coordinates, including:
5.1. Input SRS definition is metadata for input positions 5.2. Absolute accuracy estimates for input position coordinates when output absolute
accuracy is needed is metadata for input positions 5.3. Relative accuracy estimates for input position coordinates when output relative accuracy
is needed is metadata for input positions
3.1.5. Discussion
Ground Coordinate Transformation Services are considered a service category separate from the Image Coordinate Transformation Services see Section 3.2 in order to limit the size of service
categories. However, these two service categories require very similar interfaces, and they must be able to inter-operate easily. Specifically, the Concatenated Image Coordinate Transformation
Services must be able to include individual or concatenated Ground Coordinate Transformation Services.
When a Ground Coordinate Transformation Service is needed, the corresponding service for the opposite direction will often also be needed. Instead of requiring a client to handle separate Ground
Coordinate Transformation Services for each direction, it appears desirable to automatically link the corresponding Services for the two directions. This linking might be done in several ways,
including:
•
Have each Ground Coordinate Transformation Service provide transformations in both directions. Different service operations or an additional input to certain operations would be
used to select which transformation direction is requested.
•
Provide a Ground Coordinate Transformation Service with an additional operation to obtain the reverse direction Service or to obtain all the metadata needed by such a service
Editors note: These Ground Coordinate Transformation Services roughly correspond to the Geospatial Coordinate Transformation Services now in Topic Volume 12 Services Architecture,
and to the transformations being specified in Topic Volume 2 Coordinate Systems and Transformations.
The Open GIS Abstract Specification Page 29
Volume 15: Image Exploitation Services 00-115 corrigendum
3.2. Image Coordinate Transformation Services
