HKHeidemann
commented
7 years ago These are critical issues for the entire geospatial community, not just LAS. 1) I personally advocate immediately migration to OGC(2015).
2) Geoid models can be PROPERLY recorded in OGC(2015) as coordinate transforms. but this seems unnecessarily bulky when all we really need to know is, for example, "Geoid12b". In OGC(2015):
COORDINATEOPERATION["NAD83(2011) to NAVD88 height (1)",
SOURCECRS[
GEODCRS["NAD83(2011)",
DATUM["NAD83 (National Spatial Reference System 2011)",
ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT["metre",1.0]]],
CS[ellipsoidal,3],
AXIS["latitude",north,ORDER[1],ANGLEUNIT["degree",0.01745329252]],
AXIS["longitude",east,ORDER[2],ANGLEUNIT["degree",0.01745329252]],
AXIS["ellipsoidal height",up,ORDER[3],LENGTHUNIT["metre",1.0]],
ID["EPSG",6319]]],
TARGETCRS[
VERTCRS["NAVD88 height",
VDATUM["North American Vertical Datum 1988"],
CS[vertical,1],
AXIS["gravity-related height (H)",up],
LENGTHUNIT["metre",1.0],
ID["EPSG",5703]]],
METHOD["Geographic3D to GravityRelatedHeight (US)",ID["EPSG",9665]],
PARAMETERFILE["Geoid (height correction) model file","g2012Bu0.bin"],
ID["EPSG",6326]]I'm fine with the full definition being used/required, but it would be helpful if ISO/OGC would define a simpler method, perhaps following their method for identifying the Datum realization: NAD83(2011)
3) The proper usage for Compound Coordinate Reference Systems is unambiguous. In OGC(2015):
COMPOUNDCRS["NAD83 + NAVD88",
PROJCRS["NAD83",
...]
VERTCRS["NAVD88",
...]]
LAS specification explicitly cites OGC WKT 2001 as the standard for WKT dialect, but OGC(2015) has since migrated to align with ISO(2009). Address any changes to LAS 1.4 that need to happen to modernize.
In addition, coordinate with ISO/EPSG for a standardized method to identify geoid model.
Finally, standardize language for definition of compound coordinate systems (COMPD_CS tag).
Relevant discussion here: https://groups.google.com/forum/#!msg/lastools/BqKml7QPIik/0JohI5qTDQAJ;context-place=forum/lastools