<div dir="ltr"><div><div><div>Steve,<br><br></div>Essentially (leaving out the double inversions), your "case 2" does this:<br><br><case2><br>proj=pipeline<br>step proj=tmerc lat_0=49 lon_0=-2 k=0.9996012717<br> x_0=400000 y_0=-100000 ellps=airy<br>step proj=vgridshift grids=OSGM15_GTX_OSGBtoGRS80.gtx<br>step proj=hgridshift grids=OSTN15_NTv2_OSGBtoETRS.gsb inv<br><br></div>But your grid is given in geographic coordinates, not transverse mercator<br>(cf. gdalinfo output [1] below), so starting your pipeline going from geo<br></div>to transverse mercator takes you way outside the grid coverage.<br><div><br></div><div>So start doing the gridshifts, then do the projection. When doing that, you<br></div><div>get this:<br><br>$ echo -3 55 100 | cct -t0 +init=OSGBtrans:case2<br></div><div> 335948.6065 567743.2288 47.5270 0.0000<br><br></div><div>/Thomas<br></div><div><br></div><div><br><br><br>[1] gdalinfo OSGM15_GTX_OSGBtoGRS80.gtx <br><br>Driver: GTX/NOAA Vertical Datum .GTX<br>Files: OSGM15_GTX_OSGBtoGRS80.gtx<br>Size is 661, 1441<br>Coordinate System is:<br>GEOGCS["WGS 84",<br> DATUM["WGS_1984",<br> SPHEROID["WGS 84",6378137,298.257223563,<br> AUTHORITY["EPSG","7030"]],<br> AUTHORITY["EPSG","6326"]],<br> PRIMEM["Greenwich",0,<br> AUTHORITY["EPSG","8901"]],<br> UNIT["degree",0.0174532925199433,<br> AUTHORITY["EPSG","9122"]],<br> AUTHORITY["EPSG","4326"]]<br>Origin = (-9.008333333333329,61.004166666666627)<br>Pixel Size = (0.016666666666667,-0.008333333333333)<br>Corner Coordinates:<br>Upper Left ( -9.0083333, 61.0041667) ( 9d 0'30.00"W, 61d 0'15.00"N)<br>Lower Left ( -9.0083333, 48.9958333) ( 9d 0'30.00"W, 48d59'45.00"N)<br>Upper Right ( 2.0083333, 61.0041667) ( 2d 0'30.00"E, 61d 0'15.00"N)<br>Lower Right ( 2.0083333, 48.9958333) ( 2d 0'30.00"E, 48d59'45.00"N)<br>Center ( -3.5000000, 55.0000000) ( 3d30' 0.00"W, 55d 0' 0.00"N)<br>Band 1 Block=661x1 Type=Float32, ColorInterp=Undefined<br> NoData Value=-88.8888000000000034<br><br><br><br><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">2018-02-23 8:46 GMT+01:00 stevejking <span dir="ltr"><<a href="mailto:stevejking@talktalk.net" target="_blank">stevejking@talktalk.net</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Kristian,<br>
Thanks for the reply, I'll take a look at the link.<br>
<br>
For the moment, I've added the missing +step to case 3, and it now works :)<br>
I also removed the command line -t0's which I had in error put in the init<br>
file.<br>
<br>
Unfortunately case 2 is still giving the error. I even tried removing the<br>
breakline \'s.<br>
<br>
Will look more when time allows.<br>
<br>
...<br>
<div class="HOEnZb"><div class="h5"><br>
Steve<br>
<br>
<br>
<br>
--<br>
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