EmDevys
commented
6 years ago Finding: There is no ModelTag (cf. 7.2.27 in current draft) inGeoTIFF, but raster data have to be Georeferenced. Georeference mechanism in GeoTIFF is the key feature of this specification, illustrated in step3 in 2.6.3. In fact a requirement should be put forward, because Georeference information has to be provided. => Proposal to suppress the following requirement 7.2.27 Requirements Class ModelTag and replace it by a Georeference requirement after the 3 following requirements • 7.2.26 Requirements Class ModelPixelScaleTag • 7.2.28 Requirements Class ModelTiePointTag • 7.2.29 Requirements Class ModelTransformationTag as follows 7.2.2x Requirements Class Raster dataset Georeference
Requirements Class
http://www.opengis.net/spec/GeoTIFF/0.0/RasterGeoreference
Requirement | http://www.opengis.net/spec/GeoTIFF/0.0/RasterGeoreference.Presence
In order to Georeference a raster dataset, at most one of the 3 following options shall be implemented and the corresponding tags (specified in 7.2.26, 7.2.28 and 7.2.29) shall be present:
- ModelPixelScaleTag and one tiepoint encoded in ModelTiePointTag
- ModelTransformationTag
- A set of 3 (or more) tiepoints encoded in ModelTiePointTag
Requirement | http://www.opengis.net/spec/GeoTIFF/0.0/RasterGeoreference.exclusion1 ModelPixelScaleTag and ModelTransformationTag SHALL never be used together.
Requirement | http://www.opengis.net/spec/GeoTIFF/0.0/RasterGeoreference.exclusion2 ModelTiePointTag and ModelTransformationTag SHALL never be used together.
Note: The use cases and methods for using the tags ModelPixelScaleTag, ModelTiePointTag and ModelTransformationTag for Georeferencing a raster dataset is explained in Step 3 in D.6.3 Cookbook for Defining Coordinate Transformations for a raster dataset.
2.6.1 GeoTIFF Tags for Coordinate Transformations defines
2.6.3 Cookbook for Defining Transformations defines 5 cases for georeference, case 5 (multiple tiepoints, n > 3), being described as "not baseline GeoTIFF".