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Note: Although different interfaces could be used for different numbers of input and output
coordinates as listed in item 3 above, such differentiation of interfaces appears undesirable.
4.1.3. Result Data
The data produced by these Image Coordinate Transformation Services includes: 1.
Output point position coordinates, in desired SRS 2.
Partial derivatives of output position coordinates with respect to input position coordinates optional
3. Metadata for output position coordinates, including: optional
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
Result metadata is optionally returned to client software, depending on how the Image Coordinate Transformation service is called. Similarly, partial derivatives are optionally returned to client
software, depending on how the service is called. However, the ability to produce result metadata and partial derivatives when requested are required capabilities of these services.
4.1.4. Needed Data
The data needed for use by these Image Coordinate Transformation Services includes: 1.
Input point position coordinates, in another SRS 2.
Output SRS definition is metadata for output positions 3.
Image 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. Ground shape and position or elevation data for monoscopic image to ground could be
considered metadata for an image? 6.
Elevation accuracy estimates when output accuracy is needed is metadata for elevation data
7. Metadata for input position coordinates, including:
8. Input SRS definition is metadata for input positions
9. Absolute accuracy estimates for input position coordinates when output absolute accuracy is
needed is metadata for input positions 10. Relative accuracy estimates for input position coordinates when output relative accuracy is
needed is metadata for input positions
4.1.5. Discussion
These Image Coordinate Transformation Services are considered an Image Exploitation Services category separate from Ground Coordinate Transformation Services 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 see item 3 in Section 4.1.2 above must be able to include individual or concatenated Ground Coordinate Transformation Services.
When an Image Coordinate Transformation Service is needed, the corresponding Service for the opposite conversion direction will often also be needed. Instead of requiring a client to handle
separate Image Coordinate Transformation Services for each direction, it appears desirable to
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automatically link the corresponding Services for the two directions. This linking might be done in several ways, including:
1. Have each Image Coordinate Transformation Services 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.
2. Provide an Image Coordinate Transformation Service with an additional operation to obtain
the reverse direction Service, or to obtain all the metadata needed by such a service.
4.1.6. Object Model
