Le mercredi 10 février 2016 13:05:20, Peter Halls a écrit : > Ari, et al, > > ESRI handle this in a non-intuitive way: XYM is supported, but Z > always has a Measure, so is XYZM! The formal definition is here: > https://www.*esri*.com/library/whitepapers/pdfs/*shapefile*.pdf (1998) > > Shape Types having Z are defined on pp19ff where it states: > > "Shape Types inX,Y,Z Space > Shapes of this type have an optional coordinate > M. Note that "no data" value can be specified as a value for M (see Numeric > Types on page 2). > PointZ > A PointZ consists of a triplet of double-precision coordinates in the order > X, Y, Z plus a measure" > > I had misinterpreted their meaning of "optional" here and submitted a > documentation query to ESRI on being told I was wrong. The response was > that M being optional means that it can be valueless, but is always > present.
Woo, really ???? That's a genuine scoop. Unless I'm seriously mistaken, shapelib / OGR has produced XYZ shapefiles without M values for more than 20 years. I'm surprised we wouldn't have heard about that if such shapefiles couldn't be read. Or perhaps ESRI software is robust to missing M too > > Best wishes, > > Peter -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
