July 23, 2014

Amazing Photogrammetry

Author: Stockpile Reports

Stockpile Reports’ customers are usually very surprised when they view their first 3D stockpile model online.

Our Support Team loves showing new clients a peek behind the scenes of what happens after video data from iPhone measurements is uploaded to our system. The resulting 3D rendering of a stockpile is always ‘cool’—sometimes customers say it seems like magic.

We think that the 3D images are fun to look at, too! But don’t get distracted by how magically they seem to appear— there is the science of ‘photogrammetry’ behind the process of generating them. Ultimately, it is the material volume results and measurement accuracy derived from using photogrammetry that customers pay the most attention to.

Photogrammetry isn’t a science used exclusively by software engineers. You’d probably be surprised at how often you encounter photogrammetry in your own everyday life.

What is Photogrammetry?

Simply put, photogrammetry is the science of making measurements from photographs. The term “photogrammetry” is derived from three Greek words: ‘photos’ meaning ‘light’, ‘gramma’ meaning ‘which is drawn’, and ‘metron’ meaning ‘to measure’. It is the science and technology of generating 3D information from 2D measurements.

This science has existed for many years. Albrecht Meydenbauer from Germany is called the Inventor of Architectural Photogrammetry. In the 1860’s he provided evidence that photogrammetry is suited for architectural surveys and for topographic data acquisition, thus inventing the principles of photogrammetry. At the same time (and unknown to Meydenbauer), a military engineer and French inventor named Aimé Laussedat also perceived the possibilities of using camera images for topographic mapping in 1851, and built a prototype of a topographic camera in 1859.

Today the rapid evolution of digital cameras and computer capabilities, analytical software and data storage has expanded the variety of situations in which photogrammetry can be applied and processed.

We have Aerial Photogrammetry, where a camera is mounted in an aircraft and is usually pointed vertically towards the ground. Multiple overlapping photos of the ground are taken as the aircraft flies along a flight path.

There is also Close-range Photogrammetry– the camera is close to the subject and is typically hand-held or on a tripod (but can be on a vehicle too). Everyday cameras are used to model and measure buildings, engineering structures, forensic and accident scenes, mines, earth-works, stock-piles, archaeological artifacts, film sets, etc. This type of photogrammetry (CRP for short) is also sometimes called Image-Based Modeling.

Photogrammetry in Film and Entertainment

Many film producers use photogrammetry to create a 3D model of the set in a computer before they even begin shooting a movie—or commercial.

Have you seen the movie ‘Fight Club’? 1999’s Fight Club was one of the first to use photogrammetry in filmmaking, used in the ‘kitchen explosion’ scene. The Matrix is another showcase for cutting-edge movie-making techniques through photogrammetry.

You may also have seen the recent Nissan Ghost Train commercial, in which photogrammetry was used for environmental surveying and modeling around the car’s path.

Video games now employ photogrammetry to create beautiful, photorealistic environments and high quality art assets, such as in the new horror game The Vanishing of Ethan Carter.

Traffic and Crash Scenes

If you’ve ever been frustrated on the road wondering why traffic is stopped by police after an accident (or why the road is closed off) it is usually because law enforcement is using photogrammetry to document traffic enforcement and crash-scene mapping.

Pictures taken of the automobiles involved in a crash can be analyzed to determine the extent of the damage. Damage reconstruction and mapping the area is used in forensics and crime scene investigation modeling.

Of course, lawyers are often involved after an accident. There is also documentation and advice for attorneys on how to choose a photogrammetry expert to help win court cases.

Crime Scenes

If you are a fan of CSI, Bones or other forensic-themed TV shows, you may think that recreating a crime scene in great detail is mostly fictional. There is a great deal of existing processes and science supporting the investigative processes behind those episodes. Here are a few examples:

• FBI has an interesting example of using photogrammetry in a bank robbery using surveillance images.

• There is existing bite-mark image analysis used to match a bite mark to a suspected perpetrator. This matching is based on a tooth-by-tooth and arch-to-arch comparison utilizing parameters of size, shape and alignment.
• Here is a rather macabre article detailing the documentation of forensics-relevant injuries, from the reconstructive point of view, titled ‘Matching tire tracks on the head using forensic photogrammetry.’ If you want to view the full-text, it is not for the squeamish!

Photogrammetry in Sports

Want to improve your sports performance? Close range photogrammetry has been captured for the development of a virtual training system for rugby football, by tracking the movement of body segments, such as the angle of shoulder orientation and the trunk flexion of the thrower.

Team sports such US soccer, indoor soccer, handball, basketball, etc, and individual sports such as tennis benefit from photogrammetry with the aim of quantifying player’s movements. This assists in deducing the physical loads on players in real conditions for coaches.

If you are a mountain climber or a casual hiker,  you’ve probably benefitted from using topographic maps. Photogrammetry has been the science behind the creation of almost every topographic map made since the 1930’s.

Today’s topographic maps are prepared using photogrammetric interpretation of aerial photography, LIDAR and other remote sensing techniques.

Difficult to climb and remote mountains all over the world have now been modeled, as well as beloved local destinations. There are many mapped ranges, from the well-traveled Great Smokey Mountains National Park to a photo-realistic 3D model and flythrough around Mount Everest.

So, more than a century after photogrammetry’s invention, there is still plenty of room for improvement and innovation. The examples listed in this blog are a but small glimpse into current imaging possibilities and business applications.

We at Stockpile Reports are proud to be part of the evolution of photogrammetric applications! If you are interested in finding out how our system will benefit your business, or may be interested in qualifying for a Limited No-Cost Trial, please contact us.