Fast and accurate volume measurement
the reason why half of the largest mining companies use Pix4Dmapper
Drone photogrammetry for stockpile
measurement
Of the biggest 40 mining companies announced in PWC’s mining
report, nearly half of them use drone photogrammetry software
(Pix4Dmapper) as part of their mining workflow.
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.
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.
Why use drone photogrammetry for stockpile volume measurements?
Horizontally, high-resolution photogrammetric results create more precise stockpile models, and thus better volume measurement accuracy
than ones interpolated from certain measured points.
Vertically, they lower the uncertainty in Z values, which is proportional to the resolution. For example, flatter stockpiles will benefit more from a
high GSD than taller stockpiles.
High-resolution images give you more details of the mapped
stockpiles
When it comes to stockpile volume measurements, stockpiles do
not conform to a perfect shape. 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.
Volume measurement of the same stockpile in the data sets of (Left) GSD=2 cm
(Right) GSD=20 cm. Larger uncertainty in vertical direction in low GSD data sets
Pix4Dmapper allows you to adjust the reference base above which you want the volume to be measured
45°
Typically, there are several
types of stockpiles
Why is setting a precise reference base important for getting accurate volume measurement?
Imagine we have a 10-meter-tall crushed gravel stockpile in a cone shape, with a 45° angle of repose:
Standard stockpile is the most generic
stockpile type. It is constructed with
basic bucket loading and dumping
techniques.
The bottom 2 meter section occupies 48.8% of the entire stockpile
volume, while the top 2 meter section occupies only 0.008%.
The error of the height values will have much more influence for the
bottom flat part than the tip. This also explains how important to
well-define the base surface is in order to obtain an accurate volume
measurement.
Ramp stockpile is constructed high,
with a narrow ramp, and is optimal for
storing a large amount of materials in
a very limited area.
Bin stockpile is a common stockpile
type. Materials are stored in a row
of three-sided bins, with enclosures
consisting of a hard floor and walls. It
is the best solution to keep different
materials separate.
Precise volume measurement in Pix4Dmapper
In addition to generating precise 3D models for the purpose of measurements, Pix4Dmapper performs
accurate stockpile volume measurements because of its ability to customize base surfaces.
The software provides 6 different base surface-defining options in its volume management module; for
more complicated conditions, users can import their own base surface (or ground-surveyed points which
form the base surface) and use them as a base to calculate stockpile volumes. For more information on
this subject, read our support article: How to select base surface for accurate volume measurement in
Pix4Dmapper.
MEASURE FROM IMAGES
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