Opened 9 years ago
#74 new enhancement
Vertical CS and units of measure for elevation (with high resolution / accuracy)
| Reported by: | edevys | Owned by: | warmerdam |
|---|---|---|---|
| Priority: | normal | Milestone: | |
| Component: | libgeotiff | Version: | 1.3.0 |
| Keywords: | VerticalUnitsGeoKey EPSG::Uom and EPSG::VCS | Cc: |
Description
High resolution elevation grids may be in centimetric or millimetric accuracy / values, resulting in either the use of decimal values (p.e. 46.21 m - that may be encoded in floating-point values, or, a less common alternative is in integer values in cm (hee 4621 cm), with signed long (32 bits).
The definition of Vertical CS in GeoTIFF is not consistent with present EPSG registry, as already identified. However, if we would rely on EPSG regitry and define geodetic height defined on the basis of EGM2008 EPSG::1027 (for which meter unit is specified - EPSG::9001), could it be an acceptable enhancement to use cm unit for VerticalUnitsGeoKey ? What about support this by libGeoTIFF / GDAL ?
PS: the only alternative seems to use floating-point TIFF values, introducing numeric "noise" and decreasing performance when reading / writing the file.
