Capturing ground elevation height data with mavic pro

[flyinghighbro]

Hi,
Is there any software or features to be able to capture the ground elevation of an old road?
Many parts of the road are covered with lantana and overgrown foliage.
Would that stop the ground detector sensors from being able to detect the actual road height because of copious foliage blocking the road surface itself?
Thankyou

 

[Meta4]

Is there any software or features to be able to capture the ground elevation of an old road?
Many parts of the road are covered with lantana and overgrown foliage.
Would that stop the ground detector sensors from being able to detect the actual road height because of copious foliage blocking the road surface itself?

It's common these days for surveys to be carried out using drones and photogrammetry analysis of a large number of overlapping images.
Here's an example of a golf course I did last year:

But trees and shrubs will block the camera's view of the ground and show up as small "mountains".
You would need LIDAR sensors to see through the vegetation but that's going to be much more expensive and need bigger drones.

 

[flyinghighbro]

Very nice Meta4. This is interesting so that is the ground elevation heights of the golf course.
Is that done with any special hardware (other than the stock P4 or Mavic)?

What would I search for to find more info similar to create something like you've done, like the software and steps to capture the data.
When I search this topic most of what I find is related to 3D modelling, rather than the elevation of the ground.

Thanks

 

[Ansia]

You can achieve this with a normal P4 or Mavic. Just use a software like Metashape, Drone Deploy, Pix4D, etc. Basically the program takes the exif data from the photos, once it stiches them together, determine the height of each area in referrence to the height these were taken. All you need is an actual MSL point within the area photographed to get precise measurements.

 

[flyinghighbro]

Hey Ansia, this is great starting info.
Is there a mini course or something that explains all this in detail? Including how the system (hardware/software) functions to work it all out, as it's quite new to me and I'm struggling to find clear info in one place.

So I would need to manually lookup MSL data for a position within the photographed area? and this would be fed into the software.
Then would it use the AGL data acquired from the downward sensors to determine the height of the actual terrain? Which I'm surprised if this would work if the sensors are only good for 10ft i think it is.

But if the distance of the ground below from above 10ft isnt determined by the sensors then how can it be calculated using the Mean sea level , which I thought doenst give any info to the actual terrain, but rather would need to acquire the AGL as a minimum to compute this.

 

[PeteM]

The dense vegetation does not allow to accurately detect the heights of the ground below.

If you don't need precise measurements, if you just need "statistically representative" measures, you can combine the drone with a classic ground survey and combine the two results with an "interpolation algorithm".

Otherwise, I advise you to perform the entire survey without a drone.


EXIF data obtained from a drone with a normal GPS are not valid.

The result of the drone flight must be "linked" to the known coordinate points on the ground.

 

[flyinghighbro]

The dense vegetation does not allow to accurately detect the heights of the ground below.

Yep that's been covered.

If you don't need precise measurements, if you just need "statistically representative" measures, you can combine the drone with a classic ground survey and combine the two results with an "interpolation algorithm".

Sounds interesting but asking about capabilities of a drone.

Otherwise, I advise you to perform the entire survey without a drone.

Not advise I'm asking for, rather exploring drone technology and its maximum capabilities and functions.
Cheers.

 

[PeteM]

Its impossible to survey only with a drone something that is not seen because it is under something else.

 

[flyinghighbro]

Sure I understand your point, but the question has forked into what can be measured on the visible parts of the road using a Mavic Pro and existing software. Not all of the road is covered and in this case, a professional survey isn't warranted or affordable, but a general idea can be helpful as a preliminary guide. It is a road on private land. Theoretically, this would likely be good enough to get an estimate of elevation levels.
If precise measurements are required then a proper survey as you said would no doubt be needed.

 

[PeteM]

I think using Google Earth or any local cartography can give you better results than flying over the road with the drone

 

[flyinghighbro]

I think using Google Earth or any local cartography can give you better results than flying over the road with the drone

Ok interesting. Would that also be true if there was no local map and the google earth topography elevation resolution was quite poor?

 

[Ansia]

Hey Ansia, this is great starting info.
Is there a mini course or something that explains all this in detail? Including how the system (hardware/software) functions to work it all out, as it's quite new to me and I'm struggling to find clear info in one place.

So I would need to manually lookup MSL data for a position within the photographed area? and this would be fed into the software.
Then would it use the AGL data acquired from the downward sensors to determine the height of the actual terrain? Which I'm surprised if this would work if the sensors are only good for 10ft i think it is.

But if the distance of the ground below from above 10ft isnt determined by the sensors then how can it be calculated using the Mean sea level , which I thought doenst give any info to the actual terrain, but rather would need to acquire the AGL as a minimum to compute this.

I learned through trial and error, many youtube videos and reading from people in these forums.

The drones use barometer and not the VPS to calculate the height from takeoff point. So if yoy photgraph an area that has a lower elevation from takeoff point, it will show as negative. This is why you need a surveying point as a baseline. The software does the rest.

 

[Capt KO]

Inexpensive handheld GPS unit would do everything you need to set your height above sea level at some local point and also the exact lat/long. From there you can get all your other Heights as explained above. Sounds like a handy addition and you'll get more use out of it as time goes on.