Blocks are organized as pixel-high scanlines (rows), with the first scanline at the top (north) edge of the DEM, and adjacent pixels on each line increasing from left to right (west to east).
The band type is always Float32, even though format versions 4 and 5 physically use 16.16 fixed-point. The driver autoconverts them to floating-point.
dataset::GetGeoTransform() returns a simple world scaling with a centered origin for formats 4 through 6. For version 7, it returns a realworld transform except for rotations. The identity transform is not considered an error condition; Leveller documents often use them.
band::GetUnitType() will report the measurement units used by the file instead of converting unusual types to meters. A list of unit types is in the levellerdataset.cpp module.
band::GetScale() and band::GetOffset() will return the physical-to-logical (i.e., raw to realworld) transform for the elevation data.
band::SetUnitType() can be set to any of the unit types listed in the levellerdataset.cpp module.
dataset::SetGeoTransform() should not include rotation data.
As with the Terragen driver, the MINUSERPIXELVALUE option must be specified. This lets the driver correctly map from logical (realworld) elevations to physical elevations.
Header information is written out on the first call to band::IWriteBlock.
v1.1 (Oct 20/05): Fixed coordsys and elev scaling errors.