What’s your best way to measure stock piles for this? A lot of convergence, and large piles. Any ideas? Best fit would work on the smaller ones, but the larger ones look tough to get a proper floor. Suggestions welcome.
I have found that the greatest variation in volumetric measurement of stockpiles occurs in selection of
1.appropriate base / floor / or elevation plane
2. outside perimeter.
For base plane or floor measurements other programs give you more options, but if using DroneDeploy, then I recommend BEST FIT unless is it completely flat/horizantal/planar surface.
For selection of outside perimeter, draw your vector area according to actual ground around all connected stockpiles which overlap, trying to keep perimeter lying on actual ground surfaces the entire time. If you can, isolate each stockpile to measure individually however if they are connected and overlapping, then your perimeter may have zigzags and odd shapes.
I have done a comparison of a stock pile which I surveyed using our drone, measuring only 22,000 points, compared to a hired LiDAR survey which measured a million points. The hired survey MEASURED BASE PLANE AS A FIXED ELEVATION when the ground is uneven and far from flat. When I matched their elevation plane measuring volume from fixed height I got the exact same volume.
When would you recommend “lowest point” - I though “best fit” was for flat surface on a stand alone pile? Am I wrong? For instance when measuring a pile which stands alone and does not have any covergence or walls = Best Fit, vector points will slice a flat plane across the bottom and calculate volume. If “lowest point” and walls coverge, like two big piles back to back, the vector points would cut out a 3 dimentional plane. For instance kind of like an “L” if vector point were on top of pile and on lower flat floor of pile it would “cut through” pile to connect the dots?
Lowest point would be for the flat planar base, and I believe that it will even be perfectly horizantal but I’m not sure about that, whereas Best Fit as will best fit an uneven surface, and I believe behind the scenes a digital surface is interpolated and used as base… best fit is your 3D cut through a pile.
Please see: http://support.dronedeploy.com/docs/volume-measurement
from their website.
I recommend playing around with different points and testing accuracy. Also, as I mentioned, it would be good to test against a known entity so that you can be confident in your work… i.e. a pile already surveyed or perhaps even cut-volume of a building of known LxWxH. Do some math on the page to measure volumes cut-fill volumes on a known slope of square area and you know what results you should get, then compare with DD.
Is there a good way of removing a belt stacker from the equation? I tried surveying a couple piles under belt stackers and they appear to be over estimating the volume.
I imagine the best way would be to draw around the belt stacker, thereby removing it or other draw 2 separate areas, one for the whole pile and the second only a foot outside the belt stacker perimeter, and subtract the stacker volume from the pile volume. DD wouldn’t have any other automated way to handle this.
Even if you export to other CAD/GIS software and work with point clouds, I’ve found it difficult to classify these photogrammetric LAS points in similar way that LiDAR can easily determine ground and vegetation/power lines based on return values.
Hopefully the above method works well for you. You can always test the above method’s accuracy by selection a crusher section or conveyor that is over flat ground, subtraction of which should yield cut/fill of nearly zero.