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Homemade GCP's

Can anyone share what they’ve found to be the best GCP config including dimensions, color, finish, material, placement method, ect?

I’m building my own and would rather not spray paint the ground. I’m thinking of just using 12"x12"x1" painted wood with a hole in the center for a spike.

I’d love to get the groups opinion on what works best.

Thanks!

Aaron

Hey Aaron,

I always print a photogrammetric target or spray a cross! Make sure is visible from your images! 

What are you planning on for a pixel size, what is your subject and how accurate do you want to measure? Will you want to return to those points? Is the earth beneath flat or sloped? An engineered or natural surface? Oh the crazy things I’ve seen over the years! A picture of the point being surveyed, at the time of survey, can be worth a thousand words. If you write the ID of the point, on the point, life can go so much more smoothly sometimes.

Hey Thanks guys for the questions and input. I wish I had answers for you, but at least wanted to get you over what I made.

Quick description:

Wood - 12" x 11 1/8" x 3/4"

I had planned on wet sanding the tops with 1000 grit to dull the shine to reduce reflection, but I ran out of time. Also, I drilled the hole off center in case I wanted to use the center X for adjusting in Pix4D. I had planned on painting the tops of the spikes (about 8 inches long) black, but also ran out of time.

Wish me luck! :slight_smile: I’ll let you know how it goes.

Aaron you did a really great job of those. The offset hole for the spike was a great idea. If the ground is rough or sloped you could plant them in the ground on three spikes.

When possible, if I can get a unique ID placed somewhere on a target that’s legible(!) in my imagery, it can make a project with a confused photo layout or no geo-referencing a lot easier to come together.

Nice job and good luck with your mission.

Steve

I like those targets in the photo above! Nice.

When I worked for a ‘real’ aerial surveying business back in the 80’s, we just used rolls of white garbage bags. We’d unroll two strips into the shape of an X which the plane’s camera would pick up quite well. How about using crepe paper rolls or paper towels or something biodegradable? 

I have been experimenting with 300mmx300mmx2mm steel plates, painted white with black border, similar to what I saw painted on the ground on a web instructional video.  Works every well and are now looking at adding a cross. The plates are heaving enough to stay in place and not too heavy to carry around.