For most of our LiDar projects a licensed surveyor goes out ahead of use and sets GCP’s. To save time we are going to start placing our base station over one of these points. I have a few questions.
under base settings is there a way to swap what it is looking for from Longitude / Latitude to XYZ?
If answer to question one is no, I am assuming that the settings for Long/LAT is degrees?
What CRS are the LONG/LAT in? WGS84? or will it take others and if so how to you tell the system what CRS to use?
Question on Ellipsoidal height and mind you I am not a surveyor just a drone pilot flying lidar. When a surveyor provides us with a height. Is that height the height of the marker that is on the ground or is that height to the head of their GNSS?
Last question for my logging I have always had the height of my base listed. However just now noticing that I haven’t had it in base settings is that bad and when is that needed?
Hey Breis, I’m not a survey guy either but the Emlid makes things pretty easy.
Q1. I create a project in the Reachview 3 app or whatever they renamed it to using whatever stateplane I’m in, add the points from our survey guys in xyz format for us z is ortho height. Usually when I get the file from the survey guys it has both xyz and Lat/Long and ellipsoid height. When I set the base on the point I configure it from the project, it converts to Long/Lat and ellipsoid height. Save me the time from figuring all that out a head of time.
Q3. WGS84, what the M300 uses anyway.
Q4. Should be the height of the GCP on the ground.
Q5. Not sure what you mean. When I set my base on a known point I configure it in Base Settings, that where I can choose to set it from a project.
I’m just the drone guy but have learned a lot from this forum…lotta smart folks here and can probably give you all the answers you need.
thanks so much for the reply Joe. For Q1 I had watched a video online where a guy was using the old reachview app and he did as you said. Then he went under base settings and he was able to choose the point in the drop down. However in the new flow app I don’t see the option that he was using.
Little more information for Q5. In the past I would set my base settings to static and average single and hadn’t entered in my base height just left it to the default. However in my logging settings I had entered my base height.
In the new Flow app it’s under base settings, there should be a Configure option, under that I have my base set to Manual, set my Antenna height, then Choose from Project. Should bring up a list of all your projects, select the project and choose the point you want to use for your base settings.
For Q5, not sure on that one, I always set on a known point. Not being a survey guy that always confused me. I would think you would always have to set the base height but not sure. @michaelL@dpitman I’m sure either of you guys can provide input here if you have the time.
Looks like joe.gatti did a good job answering most of your concerns. As a surveyor, I just wanted to throw my 2 cents on “#5” and how I would go about setting up the base. If you are setting your base over a known point and using the base to send real- time kinematic (RTK) corrections to your rover/ drone, then I would most definitely set the base instrument height in base settings.
I would almost always prefer to have my base set up over a known point, even if it’s a quick single average position done in survey module with a rod height to get an position and elevation on the control point. With the coordinates recorded, you can always return to your control point, enter the coordinates and instrument height, and have a repeatable survey if you ever needed to go back to the site.
Someone can correct me if I am wrong, but putting the base height in the logging screen does nothing for RTK correction. The instrument height that is input in the logging screen is only used to write to the RINEX file used for post- processing. During post- processing most software will read the instrument height in the RINEX file, but you also have the ability to manually change the instrument height during post- processing. So as far as I am concerned inputting the height in logging is optional and mainly just an extra “note” of what the height was.
It looks like you’ve already received most answers to your questions, I’d add just a couple of words.
As @joe.gatti said, you can set the base in local coordinates using the point from your project. I’d only add that Emlid Flow converts these coordinates into geographical ones when the coordinate system is set for the project. So, the charm is that you don’t need to convert them manually, the app does it for you.
@snillor999 mentioned correctly: the base height in Logging settings is recorded in the RINEX header and is used in post-processing software. If you work only in RTK, antenna height that matters is only in the Base settings. However, it’s a good way to keep logging as backup and set the antenna height there too.