<div dir="ltr">Dear,<br><br>We are trying to substitute old Proj 5.1 in our project and use new Proj<br>9.2.1.<br><br>When crs is defind with proj4string or wkt, we do not have issue with<br>transforming coordinates from/to EPSG:4326, except when we are using<br>grid files e.g.<br><br>+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000<br>+datum=OSGB36 +units=m +ellps=airy +no_defs<br>+nadgrids=OSTN15_NTv2_OSGBtoETRS.gsb  +type=crs<br><br>PROJCS["ED50 / 3-degree Gauss-Kruger zone 10",<br>     GEOGCS["ED50",<br>         DATUM["European_Datum_1950",<br>             SPHEROID["International 1924",6378388,297],<br>             EXTENSION["PROJ4_GRIDS","SPED2ETV2.gsb"]],<br>         PRIMEM["Greenwich",0,<br>             AUTHORITY["EPSG","8901"]],<br>         UNIT["degree",0.0174532925199433,<br>             AUTHORITY["EPSG","9122"]],<br>         AUTHORITY["EPSG","4230"]],<br>     PROJECTION["Transverse_Mercator"],<br>     PARAMETER["latitude_of_origin",0],<br>     PARAMETER["central_meridian",30],<br>     PARAMETER["scale_factor",1],<br>     PARAMETER["false_easting",10500000],<br>     PARAMETER["false_northing",0],<br>     UNIT["metre",1,<br>         AUTHORITY["EPSG","9001"]],<br>     AUTHORITY["EPSG","2207"]]<br><br>Conversion fails with (HUGE_VAL, HUGE_VAL) coordinates.<br><br>If we allow user to define crs by proj4string or wkt and use gridshift<br>files:<br><br>- How proj4string/wkt need to looks like?<br><br>- What c++ functions we need to call to get these coordinates converted<br>without any errors?<br><br><div>Best regards,</div><div>Mladen.<br></div></div>