Phantom 4 pro and gravel pile mapping

[Skytech Imaging]

Hi guys, I've been using my P4P for mapping sites that have gravel piles. Using Drone Deploy we are able to accurately map the sites and calculate the size of each pile. Accuracy is extremely good and is saving our client a lot of expense!!

 

[shroppy]

Good to hear! Have you ever used Maps Made Easy for similar measurements? I'd be interested in hearing how you would compare the two.

 

[Skytech Imaging]

No I have not tried that service. My customer was doing it manually with someone climbing each pile holding a GPS unit on a pole. Our method of mapping using Drone Deploy has an accuracy level of 98% which is superb!

 

[Jesse G]

I'd like to hear about the workflow you use in these missions if you care to share details. I'm curious if you use GCPs, if you're using only nadir images or also adding orbit/oblique imagery as well and also how the 98% accuracy was found.

 

[Airbender]

I've used Maps Made Easy, Drone Deploy, and every other service that offered a free trial. I ended up thinking Drone Deploy would be the best solution. I found their forum robust and the principals willing to reach out and assist. All I need now is a paying gig for using it. Their $99.00/month (last I checked) is too steep when one doesn't have any regular work coming in. They do have a free plan with limitations that likely would not satisfy a paying client.

One thing I liked about Maps Mad Easy was their points system, where I can pay as I go. Here is one such project: View =>

Flying mapping missions is a hoot. Watching your drone go off and do its pre-programmed thing, even coming back for a fresh battery then heading back out and picking up where it left off. The stitching technology employed by the online services is mind boggling to me me and likely anybody who has spent time stitching simple panoramas together using PT GUI, ICE or whatever

 

[shroppy]

I quite agree about the 'points' in Maps Made Easy, unless you're doing these sort of things on a very regular basis it's probably the best way forward.

Here's a link to the results of a quick trial we did of the service using some nearby abandoned quarry workings,

Drone mapping abandoned quarry workings

 

[PatR]

Here in N. California there are several quarries that are using drones for a similar purposes by using them to track product inventories. The ones I've talked to all use GCP's.

 

[Dave Pitman]

Our method of mapping using Drone Deploy has an accuracy level of 98% which is superb!

I would be interested in how you qualify your accuracy statement? Relative accuracy can be decent without GCP's but qualifying it is another matter. thx!

 

[Dave Pitman]

I too like the value of Map Made Easy's point system for occasional work. You need to go up to DD's Business Plan ($300/month) to get the same feature set as MME. If you are doing a great amount of work per month then it may be cost effective going with DD's model.

 

[ArrUnTuS]

GCPs are important. In this case since it is not necessary to georeference, since if I have not misunderstood, it is only to calculate volumes. Good accuracy can be obtained by providing two manual scales with the sole objective of geospatially determining the actual size of the piles. It's faster and easier

 

[Dave Pitman]

Adding scale bars is a good way to add accuracy to orthoimages without GCPs. However, I don't think they are available in Drone Deploy or Maps Made Easy. They are available in Photoscan Pro and I believe in Pix4D as well.

 

[ArrUnTuS]

Yes, i use Pix4D. You can set scales and orientations.

 

[Jesse G]

GCPs are important. In this case since it is not necessary to georeference, since if I have not misunderstood, it is only to calculate volumes. Good accuracy can be obtained by providing two manual scales with the sole objective of geospatially determining the actual size of the piles. It's faster and easier

I agree that scale bars are a quicker way to achive more accurate relative accuracy. however any volumetric calculations I am involved with as a surveyor always requires a pre and post survey, or before and after. This makes GCPs an absolute necessity since without them you can not achieve repeatability since the built in drone gps is not accurate enough. Without GCPs I have seen shifts of more than 3 feet between seperate flights of the same area flown with the same drone, even if flights are from the same day. I am very curious about the claim of 98% accuracy since I have never seen anything that close without GCPs and oblique imagery. Even with GCPs when I only use nadir imagery I see much more than a 2% variation. I have been planning a case study to document this type of scenario and get some hard figures and a comparison cross-section but have not had enough time of lately to actually get out into the feild and complete it.

 

[Jesse G]

It seems that every case study I have found about this subject uses accuracy percentages or only checks accuracy on checkpoints as reported by pix4d or a similar program and never gives hard numbers like a surface being off "this many inches" or compares a traditionally suveyed stock pile to the drone data.

 

[ArrUnTuS]

It seems that every case study I have found about this subject uses accuracy percentages or only checks accuracy on checkpoints as reported by pix4d or a similar program and never gives hard numbers like a surface being off "this many inches" or compares a traditionally suveyed stock pile to the drone data.

To get those results looking for I think the Phantom is not the drone you need. I think the way forward is to forget about "traditional" GPS and move on to RTK.

However, if the coordinates of the GPC's are taken with quality equipment there should be no problem.

Read this article from Pix4D where it compares using GPC's or drones with RTK. I thought it was very interesting.

Do RTK/PPK drones give you better results than using GCPs? - Pix4D

 

[Dave Pitman]

I have now seen 2 polished and 1 rough precise gnss setups for dji RTF craft that are designed to give centimeter accurate geotags that can be PPK'd to adjust for global accuracy. Throw in a couple GCPs for ground truthing and you should be pretty good.

 

[ArrUnTuS]

I have now seen 2 polished and 1 rough precise gnss setups for dji RTF craft that are designed to give centimeter accurate geotags that can be PPK'd to adjust for global accuracy. Throw in a couple GCPs for ground truthing and you should be pretty good.

It would be the software solution, I've read a little bit about it and it seems to work well. An intermediate step, I think the RTK solution is more comfortable. Has anyone tried both methods?

 

[Skytech Imaging]

Sorry for the slow reply guys. We produce the map and our client takes it from there. They import the map and use an in house program and tell us that they can get a 98% degree of accuracy when compared to boots on the ground. I'll ask them what program they are using.

 

[Dave Pitman]

The advantage of PPK over RTK with drones is the needed live connection from the base or CORS to the rover. Eventually I'm sure this will get addressed. But right now it is problematic. Also, CORS logs are a slight bit more accurate than live CORS corrections from what I have read.

 

[ArrUnTuS]

The advantage of PPK over RTK with drones is the needed live connection from the base or CORS to the rover. Eventually I'm sure this will get addressed. But right now it is problematic. Also, CORS logs are a slight bit more accurate than live CORS corrections from what I have read.

I have never used, the truth is that since PPK corrections are post-flight, the images are geotagged again with post-flight corrections? It's just that thinking about it calls me RTK system more. Bearing in mind that the base has to be always in VLOS with the drone and that it has no connection problems with the data center to get its own position accurately.