Georeference points on 3D Model
I am lacking enough experience in order to tackle a problem. I want to lay a GPX Track that I recorded onto a photogrammetric model I computed in Reality Capture. In this case a Mountainbike Track
Here is the GPS points I recordered (red dots) along a bike trail (blue dotted line). I have that data as a csv file. The picture should help visualize the problem.
Here is approximately the same section inside the 3d model from RC. So far so good.
The model was computed based of DJI Mavic 3 Images without ground control points. I only used Control points to help align the model. The alignment report shows that it should be georeferenced based on the GPS Data. I am not sure why it says "No" for "metric" as when I use the define distance tool, it does output measurements in meters. These seem to be about accurate as I dont have a scale to verify it yet.
Now here the 3 questions:
1. Since the model seems to be scaled and georeferenced, I would imagine to be able to click onto a specific spot in the 3D model and to receive the global coordinates from that point. That would allow me to quickly check, if start/end points and other distinct points are roughly accurate. I am not sure if I am not finding a tool, or if this is even possible (in my model)?
2. Is there a way to import GPX tracks directly into RC? That way I could overlay the entire track onto the model and see deviations.
3. Am I better off exporting the model to something like blender and continue there? The only problem I see there is that the model seems to be scaled when I export it. However I am yet lacking to understand how it is referenced to its global position (Lat, Long, Alt)? Not an expert in coordinate systems either.
I understand that the accuracy of my model and the gpx track might not promise perfect results, it should mostly teach me the workflow to do it. However I will be able to compute models with Phantom 4 RTK soon and will have a Rover Accessible in Order to then more precisely evaluate GCP's. Also we will have better GPX tracking options soon and will be in even more open terrains for most projects.
Id appreciate any help on this, most forum topics seem to be too advanced to cover my needs,
Hi Jonas, I will try to answer your questions
1) It is not possible directly do in RealityCapture. To see the coordinates you need to have created control points (there is more option for that) and when you click on control point in 1Ds view, there is option to see its actual coordinates. Also, if you have created ortho, you can see the actual position if the mouse arrow above created ortho.
2) You can upload it as GCPs, but to see the precision they need to be assigned to the images (then can be used as check points). To compare model and GPX data would be better to use CloudCompare
3) You have more options when you are exporting the model. I suppose you used pre-defined settings which means that Grid coordinates were used. To export it georeferenced, you need to have set Project and Output coordinate system and during model export you need to set Projected output in Scene transformation section. It is georeferenced according to information from the images (there is written their geolocation in EXIF). But in mostly cases this is not so precise and there could be errors in meters.
ah thanks for leading me in the right direction. I did convert to wgs84 and was able to see the wanted coordinates of set control points. With this I was able to compare some key points and everything seems to be lined up quite nicely. I am currently setting up cloudcompare and will explore its capabilities.
I might however export the coordinates in a local cartesian coordinate system. With this I should be able to write a skript in blender or similar to then display the gpx track in 3D after I also converted the GPX file to said coordinate system. This gives me good options to automate the process which is where I want to go,
Thanks so far :)
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