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DJI Phamtom 4 RTK – What types of output?
Posted by Ian harvey on April 6, 2020 at 7:20 pmWe are a survey company that mainly supply topographical dwg output using RTK-Rovers on the RTK-VRS network (Trimble VRS-Now) and traditional total station captured data.
We’re looking to add a Phantom 4 RTK to our list of tools to capture data, but are unsure of the output from the drone. I understand that a photo that has the Easting & Northing information embedded in in is one output, as well as being able to create a 3d model with 3rd party software. However what we want is to also have the elevation spot data available (exportable) so it can be imported into a .dwg drawing to augment the traditional survey.
Does anyone have experience of this or can confirm that we would be able to get the GPS location exported in a usable format to import into AutoCad or LSS? Also can the orthomosaic stitched photo be included as a ‘layer’ in AutoCad?
Thanks
Ian
dave-karoly replied 3 years, 10 months ago 8 Members · 12 Replies- 12 Replies
Pix4D can export a variety of files that can be brought into C3D. You will have to do some clean up work with the contours ans spot check. Once in CAD you can make a surface and then add the ticks if you want spot elevations. Georeferenced Orthos are also possible and will drop in the correct location. You do though have to be a little tech savvy and pay attention to the details. There is a learning curve, but not too steep. The ortho images get very large fast – so you will want to look into some software that can degrade images and save “down” otherwise your CAD files will get 70-80MB real quick.
Thanks for your reply.
Would we be able to export a file from the drone with the raw Easting & Northing and manually identify the appropriate spot levels we would be interested in?
Ian
@ian-harvey
Ian,
Nothing like that is directly captured by the drone. You need to post process the drone with apps such as Pix4D to get that info.
The DJI 4RTK creates 20Mb high-resolution images in JPG format. Each image has the RTK Lat/Lon/Ell. Ht stored within the image EXIF.
The drone also creates the following files of camera event points and marks in ASCII format and GPS PPK static data in RINEX and Binary formats:
100_0004_EVENTLOG.bin
100_0004_PPKRAW.bin
100_0004_PPKRAW.sig
100_0004_Rinex.20O
100_0004_Timestamp.MRK
FYI: Topcon Magnet Tools will not import the RINEX data directly from the drone, for some reason. I use RTKconv.exe from RTKLIB: An Open Source Program Package for GNSS Positioning to convert the PPKRAW.bin (Binary Format) to RINEX format for Magnet Tools.
Thanks Lee.
Our current clients don’t see having a 3d model as a necessity and are expecting a traditional dwg line drawing. If we want to add extra data (elevation spot levels) from the drone output are the options then:-
- Send output to Pix4D for processing and then pick the data out of the returned output to add into our drawings?
- Process the output ourselves in an application like Agisoft Mettashape and pick out the elevation data from there?
Your advise is greatly appreciated as we are on the start of this journey and struggling to get our first understanding.
Cheers
Ian@ian-harvey Pix4D will export contours (Lines with elevations) when you import the contours into C3D you can create the surface from the contours. Then C3D will create spot elevations where ever and how often as you tell it.
I am afraid that I am reading between the lines here and you are using a LDD era software and getting confused on the “3D” aspect. The output doesn’t have to be 3D per se but the line work will be elevated. The world of point based data is slowly disappearing.
- Posted by: @stlsurveyor
Pix4D will export contours (Lines with elevations) when you import the contours into C3D you can create the surface from the contours.
This should work in theory, however, in reality, it doesn’t unless you’re measured a newly created stockpile of dirt. Pix4d makes an attempt to classify your data into ground, low/mid/high vegetation, roadway, etc. It doesn’t work well. You will see closed contours around vehicles, buildings and noise areas that should not be there. Global Mapper does a much better job of classification and creating contours from the point cloud. Again not perfect, but better. We use TopoDot which has semi-automatic method of creating true break lines and ground points. Then create a TIN or DTM from this data.
Civil3d and Microstation can import the point cloud directly. You can create break lines and ground shots manually, just not as easy as TopDOT or Virtual Surveyor applications. You can create 3d break lines in Pix4Dmapper and their new app Pix4Dsurveyor. This has not automation.
What @leegreen says is correct, it does take a great deal of editing, and C3D19 and 20 require a rcp file, no more direct .las file.
Site scan!!! recently bought by Esri. you can export any format you want or choose a area and export a csv and that imports directly into C3D as a point cloud. i played around with a lot of software before purchasing this subscription and it is by the best option.
here is a list copied directly from my export options. Raster Data Orthomosaic(.tiff)DEM(.tiff)DTM(.tiff)Contourscontour (.shp.zip) (DTM)Contour (.dxf) (DTM)Contour (.shp.zip) (DEM)Contour (.dxf) (DEM)Point Cloud Point Cloud (.rcs)Point Cloud (.las.zip)Point Cloud (.laz)Mesh 3D Mesh (.rcm)3D Mesh (.obj)3D Mesh (.fbx)3D Mesh (.slpk)Processing Report Processing Report(.pdf)@ian-harvey We use Virtual Surveyor to make working with the point cloud a bit easier. We are able to create a point grid with rudimentary linework in a CSV and SHP files before heading into Civil3D or TBC. It really depends on your current workflow and what you are using the point cloud data for.
Stay away from the point cloud if you can help it, that’s my advice. We process topos weekly some with drone data, some without. We process the data in Pix4d and then bring it into Virtual Surveyor to actually add the data, points, linework, surface, etc… that is then imported into Civil3d. That’s the simplest most efficient workflow we have figured out.
There are a few other tricks/tools/methods that you can use such as importing the aerial image from Pix4d together with a surface from Virtual surveyor. With those two together in CIvil3d you can literally set points wherever you need them. If your image is low enough an adequate quality you can even pick the general topo features off the map. We do most of this type of work in Virtual Surveyor but it can be done in Civil3d as well
Point clouds are pretty easy to work with in TBC and I hear Virtual Surveyor is even better for creating linework. You can’t do anything useful in TBC anymore now without a license which is a shame. I have just started working with Leica P20 scan data, using C3D and Recap and both are terrible for snaping breaklines and creating surfaces from RCP files. I get our scan guy to do them for me in Cyclone, it was just too painful working in 3D in C3D. I’ve been working with TBC for nine years and besides its really, really, really terrible drafting options, I miss it a lot. The ability to have a 2D and 3D window up at once was so good for working with point clouds from drones and scan data.
The last point cloud I generated topo from I used Microsurvey Ultimate…way better than Cyclone and Virtual Surveyor. Once I figured out the 3D zooming and panning it is pretty much a breeze. I used it to put coded point in, have Automap draw the lines then if any of the lines don’t look quite right easy to edit the point, pick a new spot, the lines automatically move.
the smart picker in Microsurvey works far better than the Cyclone version.
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