OPUS point off 0.5 m - incorrect transformation to WGS84?

I’m following this Rock tutorial (Using OPUS to compute a precise point with the EMLID Reach RS2 f) for putting the OPUS corrected point into RockDesktop and my output is about 0.5 m off horizontally when I compare the location of the base station to a DTM. It doesn’t matter if I transform the ITRF2014 to WGS 84. Is there as specific transformation I’m missing or another solution to fix this spatial mismatch?


Yes, there is a step that will help you with this. You want to take your point cloud straight from pre-processing creation and upload it to the ROCK Cloud so you can align your point cloud to your GCPs. See this article and this video for instructions. Then you can export that aligned point cloud to take to your preferred software.

Thank you Vicky. So the OPUS ITRF2014 coordinates are inherently off ~ 0.5 m in the preprocessing software even with the PPT of the base station data? I was under the impression from the RockRobotic staff that this wasn’t the case.

I’m concerned that there is some transformation error that I’m making that needs to be corrected in the preprocessing step prior to any GCP.

Hey! Can you share a project with the point cloud and the opus solution as a GCP in there, or at least grab some screen shots of the opus solution typed into rock desktop and then the point cloud with this same point in it as a GCP.

I want you check that you are correctly entering in the precise point from opus, then see the GCP screen and see what you are typing in there and what projection you are selecting for your gcp.

I’m using the ITRF2014 Lat/Long and Ellipsoidal height from the OPUS report and adding it to RockDesktop at shown in the screenshot. From what I read ITRF2014 and WGS84 are aligned so should be a couple of cm off at most, so a reprojection shouldn’t be make that much of a change.

I’m not to the step of using GCP to correct my point cloud yet. I want to isolate the reason for the error at this step of the workflow to make sure I’m using RockDesktop correctly before moving to GCPs. Thank you for the help. The community forum is useful.

Hey there! Can you send an email to support@rockrobotic.com and I’ve got a few questions I’ll respond with and then when we’re done we can post our solution here to help everyone learn? Thanks!