Gets or sets the value of the GeoTIFF GeoTiePointsTag.
Namespace:
FreeImageAPI.MetadataAssembly: FreeImageNET (in FreeImageNET.dll)
Syntax
Remarks
The GeoTiePointsTag stores raster -> model tiepoint pairs in the order
ModelTiePoints = (...,I,J,K, X,Y,Z...),
where (I,J,K) is the point at location (I,J) in raster space with
pixel-value K, and (X,Y,Z) is a vector in model space. In most cases
the model space is only two-dimensional, in which case both K and Z should be set
to zero; this third dimension is provided in anticipation of future support for 3D
digital elevation models and vertical coordinate systems.
A raster image may be georeferenced simply by specifying its location, size and
orientation in the model coordinate space M. This may be done by specifying the
location of three of the four bounding corner points. However, tiepoints are only
to be considered exact at the points specified; thus defining such a set of
bounding tiepoints does not imply that the model space locations of the interior
of the image may be exactly computed by a linear interpolation of these tiepoints.
However, since the relationship between the Raster space and the model space will
often be an exact, affine transformation, this relationship can be defined using
one set of tiepoints and the ModelPixelScale, described below, which
gives the vertical and horizontal raster grid cell size, specified in model units.
If possible, the first tiepoint placed in this tag shall be the one establishing
the location of the point (0,0) in raster space. However, if this is not possible
(for example, if (0,0) is goes to a part of model space in which the projection is
ill-defined), then there is no particular order in which the tiepoints need be
listed.
For orthorectification or mosaicking applications a large number of tiepoints may
be specified on a mesh over the raster image. However, the definition of associated
grid interpolation methods is not in the scope of the current GeoTIFF spec.
Naming differences In the native FreeImage library and thus, in the FreeImage API documentation, this property's key is named GeoTiePoints. Since the GeoTIFF specification as well as Java's EXIFTIFFTagSet class call this tag ModelTiePoints, this property was renamed accordingly. However, when accessing this property's tag by its MetadataTag object, the native FreeImage tag key GeoTiePoints must be used.
Handling of null values A null value indicates, that the corresponding metadata tag is not present in the metadata model. Setting this property's value to a non-null reference creates the metadata tag if necessary. Setting this property's value to a null reference deletes the metadata tag from the metadata model.
Naming differences In the native FreeImage library and thus, in the FreeImage API documentation, this property's key is named GeoTiePoints. Since the GeoTIFF specification as well as Java's EXIFTIFFTagSet class call this tag ModelTiePoints, this property was renamed accordingly. However, when accessing this property's tag by its MetadataTag object, the native FreeImage tag key GeoTiePoints must be used.
Handling of null values A null value indicates, that the corresponding metadata tag is not present in the metadata model. Setting this property's value to a non-null reference creates the metadata tag if necessary. Setting this property's value to a null reference deletes the metadata tag from the metadata model.
