<html><head></head><body><div class="yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" data-setdir="false"><div><div dir="ltr">Hi hi, I was looking for someplace to ask about this, and I was in doubt is was here or in PROJ, but lets do a try.</div><div dir="ltr"><br></div><div dir="ltr">Actually, probably I'm not the only one, I have some questions about how WKT2 and PROJ4Strings are transformed.</div><div dir="ltr"><br></div><div dir="ltr">From
what I read, a PROJ4String don't have enough info to construct a
precise WKT2, so, actually how PROJ4String is deprecated my main
question is how to construct the right WKT2, there is a lot o data
stored in the old format, there is usually no more information, and even
the software/hardware that get the data in some way save all of it with
all the errors.</div><div dir="ltr"><br></div><div dir="ltr">Actually, we can transform a old CRS to a WKT2:</div><div dir="ltr"><br></div><div><pre><code>> st_crs("+type=crs +proj=utm +zone=19 +south +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0"
+ )
Coordinate Reference System:
User input: +type=crs +proj=utm +zone=19 +south +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0
wkt:
BOUNDCRS[
SOURCECRS[
PROJCRS["unknown",
BASEGEOGCRS["unknown",
DATUM["World Geodetic System 1984",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]],
ID["EPSG",6326]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8901]]],
CONVERSION["UTM zone 19S",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",0,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",-69,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",0.9996,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",500000,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",10000000,
LENGTHUNIT["metre",1],
ID["EPSG",8807]],
ID["EPSG",17019]],
CS[Cartesian,2],
AXIS["(E)",east,
ORDER[1],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]],
AXIS["(N)",north,
ORDER[2],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]]]],
TARGETCRS[
GEOGCRS["WGS 84",
DATUM["World Geodetic System 1984",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
CS[ellipsoidal,2],
AXIS["latitude",north,
ORDER[1],
ANGLEUNIT["degree",0.0174532925199433]],
AXIS["longitude",east,
ORDER[2],
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4326]]],
ABRIDGEDTRANSFORMATION["Transformation from unknown to WGS84",
METHOD["Geocentric translations (geog2D domain)",
ID["EPSG",9603]],
PARAMETER["X-axis translation",0,
ID["EPSG",8605]],
PARAMETER["Y-axis translation",0,
ID["EPSG",8606]],
PARAMETER["Z-axis translation",0,
ID["EPSG",8607]]]]</code></pre></div><div><br></div><div dir="ltr">So,
in some way, GDAL is able to cover this "breach" of information betwen
PROJ4String and WKT2, but is not like the breach does not exist, it was
just handled in some way, so, the lack of info, also means, there can be
othe aproximations to that CRS.</div><div dir="ltr"><br></div><div dir="ltr">Maybe I'm just confused, and mixing things the things I read, I'm just trying to figure it out, what and how would be the right transformation from proj4string to wkt2.</div><div dir="ltr"><br></div>Thx.</div><div><br></div></div></div></body></html>