<div dir="ltr"><div>Using the option "--bbox", if I have done correctly, I get this</div><div><br></div><div><span>PROJ_NETWORK=ON projinfo -s EPSG:4979 -t EPSG:32181+5713 -o proj --spatial-test intersects --bbox '-53.6,47.7,-53.5,47.8' <br>Candidate operations found: 2<br>-------------------------------------<br>Operation No. 1:<br><br>unknown id, Inverse of Transformation from CGVD28 height to WGS 84 (ballpark vertical transformation, without ellipsoid height to vertical height correction) + Inverse of NAD83 to WGS 84 (1) + MTM zone 1, unknown accuracy, North America - onshore and offshore: Canada - Alberta; British Columbia; Manitoba; New Brunswick; Newfoundland and Labrador; Northwest Territories; Nova Scotia; Nunavut; Ontario; Prince Edward Island; Quebec; Saskatchewan; Yukon. United States (USA) - Alabama; Alaska (mainland); Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming., has ballpark transformation<br><br>PROJ string:<br>+proj=pipeline<br> +step +proj=axisswap +order=2,1<br> +step +proj=unitconvert +xy_in=deg +xy_out=rad<br> +step +proj=tmerc +lat_0=0 +lon_0=-53 +k=0.9999 +x_0=304800 +y_0=0 +ellps=GRS80</span></div><div><span><br></span></div><div><span>I could imagine that the reason is that the bbox does not intersect with the area of use of </span><span>CGVD28 heigh (despite of the geoid model file covers that point). Is there a way to workaround it?</span></div><div><span><br></span></div><div><span>Thanks<br> </span></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 21 Dec 2023 at 10:27, Javier Jimenez Shaw <<a href="mailto:j1@jimenezshaw.com" target="_blank">j1@jimenezshaw.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Hi</div><div><br></div><div>I'm trying to convert from WGS84 (or NAD83, I do not mind) to "MTM zone 1 + CGVD28 height" in Canada.</div><div>I know that the area of use of "MTM zone 1" and "CGVD28 height" do not intersect. But they told me "<span>Canadian agencies still require this datum [</span>CGVD28] <span>throughout all of Canada." Actually the geoid model grid file [</span>ca_nrc_HT2_1997.tif: Canada, Natural Resources Canada, NAD83(CSRS)v2 (EPSG:8235) to CGVD28 height (EPSG:5713)]<span> covers much more than the CRS area of use.</span></div><div><br></div>projinfo says something that makes sense to me:<br><div><div><br></div><div>PROJ_NETWORK=ON projinfo -s EPSG:4979 -t EPSG:32181+5713 -o proj --spatial-test intersects</div><div><br></div><div>Candidate operations found: 303<br>-------------------------------------<br>Operation No. 1:<br><br>unknown id, Inverse of NAD83 to WGS 84 (6) + NAD83 to NAD83(CSRS)v2 (1) + NAD83(CSRS)v2 to CGVD28 height (1) + Inverse of NAD83 to NAD83(CSRS)v2 (1) + MTM zone 1, 4.55 m, unknown domain of validity<br><br>PROJ string:<br>+proj=pipeline<br> +step +proj=axisswap +order=2,1<br> +step +proj=unitconvert +xy_in=deg +xy_out=rad<br> +step +inv +proj=vgridshift +grids=ca_nrc_HT2_1997.tif +multiplier=1<br> +step +inv +proj=hgridshift +grids=ca_nrc_NA83SCRS.tif<br> +step +proj=tmerc +lat_0=0 +lon_0=-53 +k=0.9999 +x_0=304800 +y_0=0 +ellps=GRS80</div><div><br></div><div>But cs2cs is not doing any vertical transformation:<br></div><div><br></div><div><div>echo 47.741422 -53.613219 0 | PROJ_NETWORK=ON cs2cs EPSG:4979 EPSG:32181+5713 --3d<br>258814.79 5289330.04 0.00</div><div><br></div><div>Running with PROJ_DEBUG=3 it ends with</div><div>Using
coordinate operation Inverse of Transformation from CGVD28 height to
WGS 84 (ballpark vertical transformation, without ellipsoid height to
vertical height correction) + Inverse of Ballpark geographic offset from
NAD83 to WGS 84 + MTM zone 1</div><div>that makes sense with the no-change in elevation.</div><div><br></div><div><br></div></div><div>Why is that happening?</div><div><br></div><div>I do not care so much about the version of NAD83. I tried with some and I get the same result.</div><div>The same with the source CRS. I use WGS84, but can be any flavour of NAD83.</div><div><br></div><div>Thanks.<br></div><div><div dir="ltr" class="gmail_signature"><div dir="ltr"><div></div><div>.___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ... .... ._ .__</div></div></div></div></div></div>
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