Land surveying - takeoff at an angle

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Over the weekend, I ran a test where I tookoff from a driveway that had a slight angle to it. When I plugged the data into the app and it stitched the mission together, the end result was a very inaccurate analysis. The map resolution was .3 in/pixel, the Approx Horizontal Relative Accuracy Range was 24.88 in, and the Approx Vertical Relative Accuracy Range 42.29 in. These numbers are supposed to be only 3x and 5x the map resolution.
Does anyone know if these numbers are so high because of the inaccuracy from takeoff?

Thank you
 
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Im not sure about the inaccurate numbers that you describe But be careful taking off a driveway..it's undoubtedly loaded with many pounds of rebar ! ..im sure a member here can sure help you and you might need to answer a few more questions before you get a Good Answer...stay tuned and you will get a answer soon !
 
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Good point! I park away from my lift-off point, but often forget about rebar. I wonder if that's what affected the accuracy.
 

BigAl07

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Asphalt = no rebar
Concrete - Maybe rebar

We take off from sidewalks (concrete), parking decks (lots of concrete and rebar) and have no problem. One of my most common take off points here in downtown is from the top of our parking garage where I am able to get a 360 view of everything around and below me. I'm not saying it CAN'T cause problems but at least so far we've never had issues. As always YMMV :)

I'd guess (and only guess) that having the camera tilted will cause issues. The software we use handles gimbal angles and they are always straight down.
 
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Rebar must be made of aluminum in the east USA i recon !
Big Al......but i have read many posts that have warned about take off's from a reinforced concrete with rebar...i took off in the grass a few times and when i fly the drone back because of a low battery and landed on rebar reinforced concrete...I got compass warnings....and at a few places where i fly....i have tryed to take off on concrete and got compass warnings isn't it a bad practice to do that and take off anyways ?
And in my post about.....i " only warned " about the concrete with rebar in it....and how about the posts about them taking off from the top of their cars is that right to do OR very wrong to do ? its very wrong from my reading posts here .
Thanks BigAl....and i know that your rebar is iron like ever body elses.
 

Meta4

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We take off from sidewalks (concrete), parking decks (lots of concrete and rebar) and have no problem. One of my most common take off points here in downtown is from the top of our parking garage where I am able to get a 360 view of everything around and below me. I'm not saying it CAN'T cause problems but at least so far we've never had issues. As always YMMV.
Launching from reinforced concrete surfaces is a lottery.
You can't tell how deep the steel mesh is below your drone, you can't tell if it's thin or thick rods under the drone and you can't tell if you put the drone down above a point where the rods cross or join or if your compass is in the middle of a large mesh square and not close enough to the steel to cause problems.
But I would have seen over 100 incidents which ended very badly and started with a launch from a reinforced concrete surface.
It's a very common incident that usually has a serious outcome.
It's so easily preventable that DJI should have a warning in their manuals.
Keep buying those lottery tickets and you just might get a winning (losing) ticket one day.
Almost all concrete structures are going to have reinforcing.
It's best to avoid launching from reinforced concrete surfaces, just as you wouldn't launch from a steel surface.
 
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You could try a hand launch and see if that helps any.
 
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I couldn't agree more. I'm hoping to meet other pilots who fly for surveying companies, where we could discuss our different strategies and techniques. I'm not looking to take advantage of others, but if we can learn as a collective, it would benefit all of us.
 
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What are some good suggestions for take off?
I took off on grass today had a yellow pop up gimbal overload - guess the long grass triggered this?
#opentosuggestions...
 

BigAl07

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What are some good suggestions for take off?
I took off on grass today had a yellow pop up gimbal overload - guess the long grass triggered this?
#opentosuggestions...
Many options... Landing Pad (weighted perimeter so it doesn't blow away), Pizza Box, Piece of Carpet.....
 
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Griter, did you use surveyed control points during processing?

I've been flying full-time for an engineering/surveying firm for about 3 years now and the issues you're having aren't related to your takeoff/landing location.
 

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