Plotting to Succeed Photogrammetry in the Automotive Industry

The old science of photogrammetry has quietly evolved with advances in digital technology, now known as tritop photogrammetry. Today it is a cost-effective and increasingly popular measurement tool that helps the automotive industry to develop new components and to monitor quality on the production floor quickly, effectively and efficiently.

Element has recently invested in the surprisingly mobile and versatile equipment at its state-of-the-art Wednesbury, UK, facility to help OEMs and Tier One suppliers to streamline their quality control processes. 

Meeting your product expectations as a car manufacturer

The eternal research and development question for car manufacturers is whether the products they make will match their design intentions. The concern goes far beyond performance, life safety and regulatory compliance to fine-tuning every aspect of the product to meet rising customer expectations for beauty and user satisfaction. 

This process of verification happens through a cascade of tests for materials, components, assemblies, systems and, of course, the end product. Held back only by the need to remain commercially viable, no stone is left unturned as components are put through their paces to see how they react to the most extreme conditions and unlikely-but-still-possible scenarios. 

High and low temperatures, corrosion from precipitation and sea salt, long exposure to sunlight, repeated opening and closing: cars can face some pretty grueling situations over the course of their lives. If spoilers, instrument panels, bumpers, glove compartments, doors and bonnets, for example, are defective or fail to last the course, it can be a significant commercial problem for OEMs and their supply chains.

It is one thing to conduct tests and quite another to measure the resulting impact on the component under investigation. When the components have complex geometries and fine tolerances, critical changes cannot be spotted with the naked eye and can be fiendishly difficult to measure. Over the years, of course, the old methods of dead reckoning, rulers and Vernier calipers have been replaced by metrological advances that have brought us a variety of more accurate alternatives. 

What is tritop photogrammetry?

One of these, photogrammetry, is proving increasingly useful and versatile by OEMs and Tier One suppliers alike. What’s more, the optical technology is quick and relatively affordable, an increasingly important consideration at a time of rapid development and prototyping of electric motors of autonomous vehicles.

The basic concept of tritop photogrammetry is in fact almost as old as photography itself. It allows three dimensional shapes to be plotted accurately by triangulating reference points from multiple overlapping photographs, and has been used in mapping landscape topologies for many decades. 

Nowadays, the underlying science and computer algorithms that crunch the data from photographs have ironed out distortion effects of lenses and inherent difficulties of gauging range to allow extremely accurate measurement down to 0.005 of a millimeter. The system can spot gap size changes, deformations, flush, bending, torsion, deflection and relative displacement, and is particularly useful on malleable materials or boundaries where different materials join. 

Unlike Faro arms, for example, the kit is lightweight and can tackle components of almost any size. Consisting of a high quality DSLR camera equipped with a flash and a fixed focal length, coded and uncoded dots as reference points to apply to the sample, calibrated reference bars, and a laptop loaded with powerful software, it all packs up into a single eminently portable case. 

The team at Element’s Wednesbury testing facility has deep experience of climatic and durability testing for the automotive industry. They have recently acquired a GOM Tritop photogrammetry kit to complement these services. This upgrade in capability gives clients a cost-effective, efficient one-stop solution well-suited to their development needs. Beyond that, Element can easily take the equipment on the road, bringing its service to the customer. 

“[Photogrammetry] is quick and relatively affordable, an increasingly important consideration at a time of rapid development and prototyping of electric motors of autonomous vehicles.”

The key to optimizing the benefits from the system, inevitably, is in the set-up. The only way to extract the information you need is by planning for it up front, and that is where it is useful to have Element’s expertise on hand. They consult closely with their customers to explore and meet their needs to deliver relevant results. Photogrammetry is not always the answer. For very detailed, extensive analysis, scanning technology might be more appropriate, albeit that it can be more time-consuming, more expensive, and cannot cope with highly reflective surfaces. However, where you need to investigate movement in three dimensions and you only need good – as opposed to excellent - accuracy, photogrammetry is the best trade-off between good quality and value for money. 

Once your needs have been properly agreed, and depending on the size of the sample to be tested, in Element’s hands the equipment takes up to an hour to set up and program, another half hour to photograph, and a matter of minutes for the results to come back. This process must be done twice, once before the test and again afterwards to identify changes. Because all the set-up has already been done, the second measurement is much quicker.

Used at OEMs’ or Tier One suppliers’ premises, the Tritop is useful in periodic or one-off quality control, able to quickly verify that production is within target tolerances or that just-in-time components meet your production specification. 

The Tritop system produces easy-to-understand, highly intuitive three-dimensional CAD models that can be interrogated at will, allowing before and after changes in a sample to be identified and measured automatically. Reports comprise images annotated with color-coded arrows demonstrating the direction and quantified extent of movement relative to original positions. The information allows customers to set tolerances, validate simulations, recalibrate production processes, verify specifications, or make improvements.

Of course, like all equipment, it is only as good as the operator, and must be regularly recalibrated for continued accuracy. The team of engaged experts at Element are fully trained in the use of the equipment by GOM as well as highly skilled in conducting tests to international, national and OEM standards. If you’re after that extra peace of mind, their global reputation for quality assurance is second to none.

In the rapidly evolving world of manufacturing measurement, photogrammetry is in the ascendency, hitting the sweet spot between accuracy, usefulness, convenience, ease of handling, speed and, importantly, cost.