What is Photogrammetry?
Photogrammetry is the science of taking measurements from photographs.
Photogrammetry is a powerful measurement tool in its own right; it is a highly accurate, traceable and scalable measurement technique and is applicable across a wide range of industrial environments.
Measurement with photographs
Whilst measuring using our GOM TRITOP system, physical reference points (or “un-coded markers”) are placed on the surface of a measuring object. Orientating objects (or “coded markers”) and calibrated scale bars are placed within the measurement volume.
A series of photographs are taken using a DSLR with fixed focus and exposure parameters. The photographs are loaded into the GOM software, where they are “bundled” into one measurement.
The centre points of each target marker are identified using contrast based measurements. Each photograph is orientated around the measuring object, and the spatial properties of each un-coded point are analysed in relationship to each coded marker.
This process is repeated through each photograph to accurately position each reference point in 3D space. These points are plotted as a 3D “Point Cloud”. Each reference point is given its own unique code and now becomes “coded”.
How does Photogrammetry support 3D Scanning?
When used in conjunction with GOM ATOS systems this provides a framework to capture high resolution detail without sacrificing large-scale accuracy.
Photogrammetry can quickly measure large volumes of point-wise location data where full 3D measurements may not be suitable. Reference points are placed in areas of interest to measure surface deviation relative to CAD data which can be output in the form of colour maps. Reference points can also be strategically placed to create elements for reverse engineering projects (e.g. constructing planes, holes, diameters, angles, distances, etc.). To further add to its versatility, photogrammetry is non-contact during measurement, maintains high accuracy over large volumes and can work in all environmental conditions.
Point clouds can be measured in both static and deformable cases, allowing for measurement in loaded and un-loaded configurations. Sequential measurements taken of a deformable object (as shown on the satellite image above) can allow for measurement of 3D displacement, bending, torsion and deflection. Photogrammetry can allow for verification of FEA modelling and can be integrated into factory acceptance tests.
To find out more about how Photogrammetry measurement can be used to support your project, as a standalone measurement solution or in conjuction with our GOM 3D Structured Light metrology, contact our team today on firstname.lastname@example.org.