This interview was conducted at the conclusion of the presentation by Dan Martin, Northeast Regional Geodetic Advisor at NGS, on OPUS Projects.
August 15, 2015
Eric Colburn- Okay, thank you Dan, that was awesome. I think we do have some questions.
Somebody asked- “Can you use the same GPS equipment as regular OPUS?”
Dan Martin– Yes, and as a matter of fact it is mandatory. Again, like I indicated, OPUS S, OPUS Static, is the front door to OPUS Projects. So, it has to pass muster through OPUS S to make it to OPUS Projects
Eric Colburn– I had a general question, I know it’s a question I’ve come up with every time I go to use one or the other- essentially, what is the difference between Rapid, Static, and regular OPUS?
DM– Well, lets see- the one minute explanation. OPUS S uses long duration observations- two hours or more. So, two hours up to 48 hours. When you upload the data to OPUS Static, it will process your data relative to three CORS stations. Actually, it processes your data relative to five, and takes the best three of those solutions and averages them in order to give you your OPUS solution position.
DM– So basically, (OPUS S) is based off of three vectors, longer observation time, three vectors and its averaged. OPUS Rapid Static will take anywhere from 15 minutes of data up to 2 hours of data. It will process your rover position relative to up to 9 CORS stations that are within a certain distance and a certain geometry of your rover station. It will also then, rather than just averaging those 9 solutions, it does- its very similar to what a VRS type or network solution might be where it actually does interpolation for ionosphere and troposphere corrections and then will do a least squares adjustment of all of the data. So it’s a little more rigorous and it (OPUS Rapid Static) allows you to use shorter observation spans.
EC– I was wondering, I’ve had limited success with it honestly, but a lot of times I’m working down near the coast and I don’t have a lot of (GPS) stations.
DM– Yup, well that has to do with, well let me show you. So if you’re down on the coast, remember I said that OPUS Rapid Static uses a certain geometry. So on the coast, your geometry suffers because you don’t have stations out in the water. And that’s why you see the accuracy degrade along the coast and maybe even some little blocks where in theory it won’t work in that location.
EC– Right, I see that.
DM– And we recommend to do the same thing when we hit the Canadian border, unless we are incorporating CORS stations in Canada, which we do in some cases. You can see up here in Northeastern Vermont, you know its like we are up against the ocean because there’s no CORS stations.
EC– Alright, somebody has asked, “At the beginning of the session, you mentioned that Project Managers have different access to features than someone with the Session access. What can a Project Manager do in a project that a Session Manager can’t do?”
DM– Well, everything that you saw me demonstrate today can be done by a Project Manager. The only thing that a Session Processer can do is process a session. So they can’t go in and change the preferences, they can’t do the network adjustment at the end, they can’t go in and modify station names. All they can do is process sessions, period.
EC– Alright, I think that’s it for questions. Thank you, Dan, for your time. It was a very good presentation, I know I enjoyed it. I recently saw you speak on another presentation, and I know you mentioned that there is someplace on the NGS site where they can find other webinars that NGS is hosting, other events.
DM– Sure, if I go to the NGS homepage, and I go under the Science and Education (tab), we do a monthly webinar series and you can sign up to receive a monthly notice (about these webinars). It gives you a list of the webinars that are upcoming and what the topic is.
EC– Excellent, well again, thank you very much for your time this morning, we appreciate it. And again, very good presentation, I know I learned a lot about OPUS projects.
DM– Thanks for having me Eric.