<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hello,<div class=""><br class=""></div><div class="">I’m trying to convert ITRF92 (epoch 93.0) coordinates to ITRF2014 epoch 2023.0.</div><div class="">Having some 8 cms per year movement I expect some 2.4m difference in the coordinates.</div><div class=""><br class=""></div><div class="">I tried some syntaxes but did not understand clearly how (where) to indicate the epochs (initial and final) in my tests :</div><div class=""><br class=""></div><div class="">One test applied was :</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">echo -139.57736536 -8.95162075 2.234 2023.0 | cct +proj=pipeline +step +proj=cart +ellps=GRS80 +step +proj=helmert +x=-0.0154 +y=-0.0015 +z=0.0708 +rx=0 +ry=0 +rz=-0.00026 +s=-0.00309 +dx=-0.0001 +dy=0.0005 +dz=0.0033 +drx=0 +dry=0 +drz=-2e-05 +ds=-0.00012 +t_epoch=1993 +convention=position_vector +step +inv +proj=cart +ellps=GRS80</span></div></div><div class=""><br class=""></div><div class="">Which gave me </div><div class=""><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">-139.5773658008 -8.9516192265 2.1701 2023.0000</span></div></div><div class=""><br class=""></div><div class="">As result. Difference much lower than expected representing some 20 cm variation from one epoch to the other.</div><div class=""><br class=""></div><div class="">I indicated the final epoch desired in my input and the initial epoch in the helmert transform.</div><div class="">This is probably false, but I did not encounter this kind of indication in the documentation.</div><div class=""><br class=""></div><div class="">Where is the misunderstanding?</div><div class=""><br class=""></div><div class="">Thank you for any help,</div><div class=""><br class=""></div><div class="">Alain Orsoni</div></body></html>