Targets for SUAS and traditional photogrammetry are not the same animal. The matrix that dictates placement and density is about all they share.
Painted targets with alternating colors have given us great results. If the soil is too loose to hold paint we use a 12 by 12 tile. Anything larger than that is a waste if you are flying under a few hundred feet (which most of us are).
The alternating flo blue and white targets we paint are extremely easy to pick out. Point numbers painted at the upper right about 6 inches tall are easy to read without zooming in tight. The paint will fade in a few weeks but can be seen by the trained eye for months. Not having to pull a tile means the panel becomes project control. It also means I dont have to walk the site again to pull tiles. I simply grab my ground truth and critical tie points as I paint my GCPs. Carry a handful of tiles in case i hit a large sand area. Done.
It is wise to learn whats going on behind the curtain. It saves you a lot of extra work. It also improves your results and BUDGET. ?
I have no idea where they got the design for this one...does not look like a good drone target.?ÿ
Actually, I am not sure if it is for regular aerial work or a drone, in any case it looks somewhat ridiculous. I know they fly drones, so I assume that is what it is for.
I have no idea where they got the design for this one...does not look like a good drone target.?ÿ
Actually, I am not sure if it is for regular aerial work or a drone, in any case it looks somewhat ridiculous. I know they fly drones, so I assume that is what it is for.
This wouldn't work for LiDAR or OrthoPhoto because it's not on the surface. Depending on the product we're creating, sometimes the tolerances are limited to 2cm, and that's a huge PITA when reducing the data.?ÿ The Ground Sample Distance (GSD) is the bottom line in these two interesting fields that I'm constantly getting schooled and developing new processes for currently.
Just used this today.?ÿ 24"x36" Endura Cor Plastic sign blanks. Cut in half to make an 18"x24" target.?ÿ Used black duct tape to create an X across the sign.?ÿ Nail and shiner in the middle for the control point.
So $40 for the signs, and a roll of duct tape for $8.?ÿ I made 20 targets for less than $2.50 each.?ÿ Will go out and pick them up by Friday once the drone has finished.
That elevated target wouldn't work for conventional photogrammetry either, never have I seen such a thing.
SHG
Neither Pix4D or Photoscan will take kindly to that - both will struggle to allocate an accurate height if it is used as a control point. Painting crosses on boulders has a similar effect (rubbish result).
Both much prefer to have the photopoint set at about ground level. I've used raised boards before for LIDAR operations when they were used for accuracy proof, but these were 8x4 sheets of ply set up level on pegs, so they would get a couple of hundred hits by the LIDAR.
With regards to Lee's comment on cross sizes - it depends on the camera being used. With a 24mp Sony we find that 9 inch crosses are fine from 320ft. when painted on hard surfaces. I appreciate that when the marks are scattered around in an area of little detail then the boards need to be larger; we then use 16 inch square ones for one-off jobs and 2 ft. square for long-term (depending on likely vegetation growth).
That elevated target wouldn't work for conventional photogrammetry either, never have I seen such a thing.
SHG
Neither Pix4D or Photoscan will take kindly to that - both will struggle to allocate an accurate height if it is used as a control point. Painting crosses on boulders has a similar effect (rubbish result).
Both much prefer to have the photopoint set at about ground level. I've used raised boards before for LIDAR operations when they were used for accuracy proof, but these were 8x4 sheets of ply set up level on pegs, so they would get a couple of hundred hits by the LIDAR.
With regards to Lee's comment on cross sizes - it depends on the camera being used. With a 24mp Sony we find that 9 inch crosses are fine from 320ft. when painted on hard surfaces. I appreciate that when the marks are scattered around in an area of little detail then the boards need to be larger; we then use 16 inch square ones for one-off jobs and 2 ft. square for long-term (depending on likely vegetation growth).
Ultimately it isn't the camera that is the limiting factor.?ÿ Its the Altitude at which collection is occurring at, the resolution of the product, the required Ground Sampling distance (GSD), and for me and the group I work with , the contract specifications and expectations lined out by the ASRPS, FDGC, NGS, USGS, and all the other alphabet agency based requirements we have to participate with for our work.?ÿ Drones don't meet any of them in general(normally), but can be used as effective tools for less stringent data collection and be useful for client satisfaction and business development.?ÿ Just my $0.02
Lee had commented?ÿ "I can't see how you guys can find those small 1'x1' targets from 200' on large projects. You must fly much lower." and my comment regarding the camera was specifically in relation to that. I wasn't suggesting that SUAs would collect data at altitude to the same standards as conventional manned aircraft. However they can, under the right conditions, collect overall data as well as a ground walking surveyor.
Lee had commented?ÿ "I can't see how you guys can find those small 1'x1' targets from 200' on large projects. You must fly much lower." and my comment regarding the camera was specifically in relation to that. I wasn't suggesting that SUAs would collect data at altitude to the same standards as conventional manned aircraft. However they can, under the right conditions, collect overall data as well as a ground walking surveyor.
Absolutely.?ÿ I wasn't starting a conflict at all, just my perspective.?ÿ And I fully believe in my lifetime, manned aircraft and robots will be doing most of the things we do now, save the decisions and research, and true depth of what surveyors do.
Lee had commented?ÿ "I can't see how you guys can find those small 1'x1' targets from 200' on large projects. You must fly much lower." and my comment regarding the camera was specifically in relation to that. I wasn't suggesting that SUAs would collect data at altitude to the same standards as conventional manned aircraft. However they can, under the right conditions, collect overall data as well as a ground walking surveyor.
Absolutely.?ÿ I wasn't starting a conflict at all, just my perspective.?ÿ And I fully believe in my lifetime, UNmanned aircraft and robots will be doing most of the things we do now, save the decisions and research, and true depth of what surveyors do.
I don't know, as they are not my targets. I noticed this in the web and thought it might be a good idea.?ÿ
Myself, I have found that a can of paint for targets on pavement and commercial?ÿ 3'x3' iron cross targets work just fine. I can't see how you guys can find those small 1'x1' targets from 200' on large projects. You must fly much lower.
I couldnt agree more about not being able to find those tiny little targets. I've never had good luck finding or processing with them. I always use the commercial 3x3 iron cross targets and they work perfect.
You could easily "resolve" it. Have you done the processing for aerials before? I find that its significantly faster and easier to spot the target when its a 3x3 target opposed to anything smaller. With hundreds, sometimes thousands of pictures, I want to be able to very quickly discern where the target is from my list in the thumbnail.?ÿ
If you can't resolve a 1' target then how can you model any resolution approaching that??ÿ
Ryan,
I agree with you. Much better working with commercial grade 36" iron cross targets.
I think some of these people are hobbyists?ÿat best, from the comments and looks of these makeshift, low budget targets. It is obvious they have not had to sort through hundreds?ÿof photos at 200 to 300 ft, to find a 12" target, made from 6" black/white tiles.
We have a profitable SUAS program that I started late last year. Our 'low budget' targets look like LED lights without even zooming in. Picking true center isnt difficult at all. Having the point number painted upper right and a good control map helps
These targets are one foot square alternating flo blue and white. We fly at around 140 to 180 as our camera is only 20 megapixels (DJI 4 Pro).
I realize thats entry level, but it's no hobby. We are putting out solid products and making good money.
