Volume Measurement from a Hole

I was wondering if I am able to measure how much dirt came out of a hole/trench in the ground? I have the business plan. Would I just fly a 3D map or Ortho map of the area to be measured? Then would one just outline the edge of the hole with the volume tool? Any help on this would be great!

Thanks,
Bryan

Normally you would do a volume annotation on the stockpiles. Or are you trying to take off the hole to figure out how much it will take to fill it?

Hi, I have client that has removed dirt from one area, leaving the hole and has trucked it out to a job site. I guess there are discrepancies on how much dirt was moved between him and the contractor. He was wanting me to map the site with the hole and get a measurement from that. Im new to the measurement side of things so any help is appreciated.

Thank,
Bryan

Yes you can quantify a hole tracing just like a stockpile perimeter. It will tell you fill. Thing is that there is a swell factor around 1.2-1.5x so there will be a discrepancy.

Thanks Michael. It will be interesting what I come up with for a number. How would you recommend flying the site? The site is a 2 mile “trench” along a river. Would I just ortho map it and get my numbers off that or should I 3D cross hatch it?

Bryan

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What mobile device are you using? I would use Corridor flight Plan if you have access to it. Standard nadir images are usually the best because you need to see down into the trench. Can you provide any area info so that we can take a look? How wide is the trench?

They are digging along a river channel. It has filled in over the years from the surrounding crop soil

The trench is probably 130 ft wide. They come down off a dirt dike system and are digging along the bank of the dike. Im using an ipad for the flight. The screen shot is from a few years ago, but it show where they had gotten material from the spot before. Now I guess they have cleaned it all out for 2 miles.

Bryan

Very cool. Definitely corridor flight. Set your altitude to get a 1in/px GSD and set you corridor width and overlaps to get 4 lanes. You could probably do this one with two lanes but since you are doing volume calcs I would do 4. Unfortunately they don’t allow it to configure an odd number of lanes but I have requested it. @Andrew_Fraser :wink: You’re probably going to need two separate flights to maintain VLOS so make sure the two flights but up to each other. You can then upload all the photos at once to make one map and just delete the other flight that is there. It will only have the border for whichever flight you use so you’ll need to extend it to capture the other points.

Hey Thank You very much for all the help. I will plan it out to get the 4 passes instead of the 2, down and back. I will plan this in 2 separate flights then upload all images into one map. Weather permitting, I hope to get this done this weekend.

Thanks again,
Bryan

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In reading up on this, it seems as tho the lower flight has higher resolution for getting more accurate measurements. But when I go below Altitude of 250 dronedeploy suggests 250 or more. I know you said set to 1in per pix but that would be pretty high. So i have it set to half that to get better data. Is this right?

Bryan

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Correct. We try to fly no higher than 225ft AGL. Point being that you don’t want to go above 1in/px. You’ll get many more tie-points which will help your slopes Since they don’t typically get a whole lot of attention in processing because it’s searching for the major grade breaks so the tops and toes are emphasized. What overlaps did you end up with?

Great. Thanks. I currently have the 4 lanes at 75 front and 65 side Overlap.

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Also, would I use the lowest point option to get the best measurement for how much dirt came out of the trench?

Bryan

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I would do triangulated for a stretch like that. Maybe even cut it into multiple measurements. Either way should be close.

Will do. Thanks again for all your advice on this!!

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So today I get to the site to find there is “No Hole” or Trench in the ground. They have removed dirt from the surface and have dug into the existing river dike. Above photo shows what it looks like. I did fly my ortho map over the area and its uploading now. I doubt I can get a measurement of what they hauled out from this. They do have lidar overlay of what it looked like before. Anyway I can put that in a shape file and get a before and after measurement? Also, if I mapped this before they dug then after, how would I compare the maps to get measurements of dirt removed? Or maybe I cant. I would appreciate any help on this.

Bryan

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Looks to me like they have just stripped the topsoil for use later and should now be bringing in a dozer or some other grading machine depending upon the depth of the channel. It would be advantageous at this point so they can get a better baseline of where they are but you can also quantify the topsoil for them. Do you have any more pictures maybe looking down the line?


Might be hard to see. They are done moving dirt out. The main contractor is using the before measurements from lidar taken in 2010 of the area. Is it possible to export my current ortho map into a lidar file or xyz file in point cloud for them to compare the before and after in? Can one get volume measurements by doing that? This is making my head hurt. :laughing:

Bryan

You might check out CloudCompare. There is a free version that you can get familiar with - better than a Trial. Anything more complex than that is going to be a paid software like Recap but it is pretty limited as far as analysis.

We use Carlson Precision 3D Topo which is a point cloud editor that will do pretty much anything you would want to do with a drone but also import/exports pretty much any design format for this kind of data including CAD. There’s also Polyworks and Global Mapper.

This type of analysis has been around for a while but the mass of people are just starting to use it so it will just take time for it to be tweaked for drone use. They are all pretty weak but getting better.

DroneDeploy can do flight to flight comparison and you can also import SHP surfaces. I don’t know of any other processing solution that can compare two surfaces/point clouds but I am sure there is something. Maybe Metashape with some Python coding. Pretty much all of them can do volumetrics but not comparisons.

As for your situation in the stage that I think it is at you might communicate with the construction team exactly what stage they are in. I would catch it when all or at least most of the topsoil has been stripped. Maybe one in between the stripping and reaching the bottom of the channel. Maybe one in between reaching that subgrade and the final asbuilt. That would be enough to get use to the data and provide them with beneficial benchmarks to know where that are at.