Show us your Ground Control Point targets - Share your experience

I don’t think so but I don’t know for sure. I use Pix4d that doesn’t do autodetect. From what I’ve seen from Dronedeploy it seems it’s been trained to pick up any GCP

Yes, DroneDeploy is hard at work with their AI. They now have a suggested target configuration and it will grow as time goes on.

I am on the Customer Advocacy Council so please submit your suggestions!

Bumping the poll…

There’s a lot of good inspiration in this thread! I love seeing everyone’s innovative solutions - particularly the lightweight and cost-effective solutions. :slight_smile:

I map in coastal areas, so I use a mix of water-based spray paint for hard features, and printed 1.5 x 1.5 FT vinyl banners with tent stakes. I run a tether line from one of the stakes to the banner so I can buy some extra time if the tide starts coming back in. That was a development after losing a couple of earlier banners.

We started numbering spray-painted points and vinyl banners to make it easier to match GPS reference points to photos in post. That’s been a huge timesaver.

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This is fantastic! Hopefully GCP location AI continues to improve and the initial search will be right at it. One of the things I enjoy most about these forums is when people collaborate and get to see use-cases way out of their norm. I’m in construction and have learned a ton of tips from agriculture, marine and environmental users!

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I do many flights in urban areas so I have the luxury of being able to place any white mark on bitumen and have it very identifiable from most altitudes I fly. I use chalk paint so as to not permanently deface the landscape. I’ve also been pushing the contrast in order to figure out the lightest surfaces I can still have a visible white mark on. This has resulted in me marking light coloured concrete sidewalks, and dirt. Circle and dot target very easy to find quickly when browsing the aerial photos. If I don’t have hard surfaces I use a roughly 1’x1’ black painted craft wood board with approx 30-40mm white dot in the middle.






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Nice! I primarily work in fabrication areas where the paved areas are covered soil or mud, and where machinery works constantly (volume measurements), so I can’t make permanent markings (put down 40 cm screws instead. Then I lay my GCP’s centered on top of these for each job, so I don’t have to remeasure each time.
The client paid for the installation-time and hardware, and we then went from 4-5 hours onsite to 1 hour onsite. Win/win for both.

Do you find you have lack of precision not having a cross or small do when placing your rover rod?

I don’t think I can identify the mark in photoscan any better than I can centre the GPS pole, probably a bit worse. So there’s nothing to gain for me in squeezing out a few more mm; I’m not wanting for more horizontal accuracy.

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We use old CDs secured with nail with washer. Metallic side up we use as GCP for thermal cameras (they show as -30°C or less since they reflect sky).

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I like this. again a smaller area, as small as you can easily recognize I think is the best because it localized is your vision to the center.

Very close to my method when I am marking surfaces of that nature. You might find that the White markings are more visible if you put down a scratch of black paint before you put the white or outline the white with the black. manhole covers are my favorite. I just have to be careful with them because they can change elevation somewhere around paving time.

I do, if needed

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We use this ones:

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What precision do you require from your work?
I see the rover rod seems offset by 5 cm on both vertical and horizontal axis in relation to the tip of marker?

This is an example of what I referenced previously. Because of the way photogrammetry and GCP’s work several centimeters will make little to no difference. In the overall model. We have to switch gears from survey to mapping and photogrammetric modeling.

We use this pattern for TXDOT panel control. Because it is also visible from planes.

Well, depends on your purpose right?
If you are mapping 5 sq km, sure 5 cm of doesnt really affect much. But then again, if you have to do is place the rover rod right, then why not?
Also, don’t you deliver the error to the client as well?

On the other hand, for the volume measurements I do, 5 cm error would be huge.

How about running a map twice and running a cut/fill scenario and stockpile report between them and let’s see what kind of deviations you see? Then run it a third time purposefully missing the tags by a couple of cm and run the tests again. Whether it’s 5sqkm, 50ac or 5ac. I am the customer and know what the numbers are and the significance of them.
That being said, yes of course we locate the exact center with a level road and try to get close to the center when tagging, but trying to hyper-analyze part of the process that makes little to no difference on the final model is fruitless. You’d be better off learning more about flight patterns and processing.

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Thanks for the hint. Unfortunately, I have posted photos showing situations before we were to measure the points. Of course we measure exactly at the tip of the marker. We want the best possible accuracy.

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Of course we are all here for best accuracy, but I want to help people understand the process and what it is capable of. I have produced over 400 maps and have never comprised my survey process or drone pogram SOP, but I also know when I am spinning my wheels.