įor the sample spacing, there was no difference because there is a minimum sample count used of 128 samples in each direction across an area, so even if you made the Sample Spacing bigger it would just use a much smaller one to get 128 samples in each direction. If you are using the 64-bit v15 version there is a new build at.
#STOCKPILE AREA CALCULATOR DOWNLOAD#
Simply download that file and extract the contents into your existing v15.xx installation folder to give it a try. I have placed a new build at with the latest changes for you to try. I also updated the Total Volume to be cut minus fill rather than adding them together to get the volume between the cut surface and terrain. Once I found and fixed that then the volume agreed with Pix4D within a few cubic meters. I dug into this and determined that you are indeed correct, the pile volume in GM was incorrect! It turns out that a single representative elevation from the center of the area was being used to create the base terrain to select from the pile surface rather than a true 3D area surface from the elevations at the area edge. PS: Besides the workspace file uploaded, there are two files on my Dropbox (too large to attach): The description claims that small values are more accurate - why are there no differnces at all? To my big surprise without any effect, not even a Q3) Looking for differences in the two volume calculation methods, I changed GM's "sample spacing",įrom the default 0.019m / 0.019m to 1m / 1m. I would expect fill_vol to be subtracted from cut_vol, like in pix4Dmapper. Q2) Why does Global Mapper add cut_vol and fill_vol in order to determine the total volume of a stockpile? Pix4D claims to use linear triangulation methods, to determine the base of the stockpile. Q1) Do you have any explanation for the big difference between the two calculation approaches? However, the difference in terms of volumes, 100 m^3 (about 20%) seems to be very large.
#STOCKPILE AREA CALCULATOR SOFTWARE#
I'm aware of the fact that the two software packages don't necessarily apply the exact same algorithms. Notice that while the volumes are pretty different, the enclosed area is exactly the same. However, applying the very same stockpile calculation in pix4DMapper, an aerial photometry software package used for DEM and ortho generation, leads to substantially different results: Not surprisingly, all 3 methods deliver the same results: I then calulate the volume with one of the following methods:Ī) Analysis/Measurement > Pile Volume (extended GEM function)ī) Analysis/Measurement > Volume, Use Heights from Terrain Surface at Boundary (.)Ĭ) Analysis/Measurement > Volume, Specify the Base height to use at each vertex, 0m "above ground" (for any vertex) In order to determine the stockpile volume, I define an area feature (polygon) with 6 vertices.
For example, flatter stockpiles will benefit more from a high GSD than taller stockpiles.I'm still struggling with volume calculations on uneven terrain, hence I performed a pretty simple test with a stockpile on relatively flat ground. Vertically, they lower the uncertainty in Z values, which is proportional to the resolution. Horizontally, high-resolution photogrammetric results create more precise stockpile models, and thus better volume measurement accuracy than ones interpolated from certain measured points. A photogrammetric survey with a fine ground sampling distance (GSD, which indicates the actual distance each pixel represents) is able to better describe irregular stockpiles in detail. When it comes to stockpile volume measurements, stockpiles do not conform to a perfect shape. Why use photogrammetry for stockpile volume measurements? High-resolution images give you more details of the mapped stockpiles These top mining companies claim that by applying the photogrammetry workflow with Pix4Dmapper, they can achieve measurement accuracies of around 2-5% for their stockpile volumes. Of the biggest 40 mining companies announced in PWC’s mining report, nearly half of them use Pix4Dmapper photogrammetry software for stockpile measurement and volume comparison as part of their mining workflow.Ĭalculating and managing stockpile inventory, that is, finding a solution for accurate volume measurement and easy inventory management, is one of the biggest challenges in the mining industry. Speed and accuracy: that's the reason why most of the largest mining companies use drones and photogrammetry software in their workflow.
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