Basics of Photogrammerty

Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography and can be dated to the mid-nineteenth century.

In the simplest example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale s of the image is known. This is done by multiplying the measured distance by 1/s.

A more sophisticated technique, called stereophotogrammetry, involves estimating the three-dimensional coordinates of points on an object. These are determined by measurements made in two or more photographic images taken from different positions (see stereoscopy). Common points are identified on each image. A line of sight (or ray) can be constructed from the camera location to the point on the object. It is the intersection of these rays (triangulation) that determines the three-dimensional location of the point. More sophisticated algorithms can exploit other information about the scene that is known a priori, for example symmetries, in some cases allowing reconstructions of 3D coordinates from only one camera position.

Photogrammetry is used in different fields, such as topographic mapping, architecture, engineering, manufacturing, quality control, police investigation, and geology, as well as by archaeologists to quickly produce plans of large or complex sites and by meteorologists as a way to determine the actual wind speed of a tornado where objective weather data cannot be obtained. It is also used to combine live action with computer-generated imagery in movie post-production; Fight Club is a good example of the use of photogrammetry in film (details are given in the DVD extras).

Algorithms for photogrammetry typically express the problem as that of minimizing the sum of the squares of a set of errors. This minimization is known as bundle adjustment and is often performed using the LevenbergMarquardt algorithm.

Photogrammetry uses methods from many disciplines, including optics and projective geometry. The data model on the right shows what type of information can go into and come out of photogrammetric methods.

The 3D co-ordinates define the locations of object points in the 3D space. The image co-ordinates define the locations of the object points' images on the film or an electronic imaging device. The exterior orientation of a camera defines its location in space and its view direction. The inner orientation defines the geometric parameters of the imaging process. This is primarily the focal length of the lens, but can also include the description of lens distortions. Further additional observations play an important role: With scale bars, basically a known distance of two points in space, or known fix points, the connection to the basic measuring units is created.
Each of the four main variables can be an input or an output of a photogrammetric method.

This method is commonly employed in collision engineering, especially with automobiles. When litigation for accidents occurs and engineers need to determine the exact deformation present in the vehicle, it is common for several years to have passed and the only evidence that remains is crime scene photographs taken by the police. Photogrammetry is used to determine how much the car in question was deformed, which relates to the amount of energy required to produce that deformation. The energy can then be used to determine important information about the crash (such as the velocity at time of impact).

The use of Photogrammetry in Automotive Repair due to accidents or collisions provides Infinite Measuring possibilities and Infinite Data collection. This allows the mechanic or technician to measure unlimited points of damage with full XYZ position results. After creating a stereoscopic image of the vehicle you can now select your choice of any two pixels to measure. There are literally millions of choices with unlimited possibilities.

The result is that trial and error in the repair process can be reduced to a minimum. When repairing complex head light openings and difficult side hit damage, you can map the good side of the vehicle (or image another undamaged vehicle) providing an XYZ road map for the repair. Repair times are reduced by up to 40%! Imagine replacement parts that fit the first try. The data that you have created is quickly and permanently stored in your Custom Data Library for further use. In addition, estimating becomes much more accurate, reducing supplements, increasing efficiency and profitability at the beginning of the repair process. Fewer vehicles will be unnecessarily totaled.

Automotive Electronic Measurement Equipment on the market today tends to use a complicated system of laser measurement, which is difficult to set-up and callibrate in the field. With the Matrix Wand it is as simple as using a digital camera, while providing more accurate results. The Wand allows:

+ More Accurate Automotive Repair Estimates or Estimations.
+ Precise Digital and Electronic Measurement of Automobiles or Vehicles.
+ Proof to Insurance Companies regarding particular collision repair damage.
+ Choose and Measure Any Point
+ Reveal Hidden Damage
+ Prove Severity of Damage
+ Predictive Wheel Alignment
+ Zero Structural Supplements
+ Provide Proof to Insurance Companies
+ Verify Repair Quality
+ Accurate Estimates
+ In-Field Calabration

Purpose and Protocols

The purpose of the study was to determine the "Real World " function of the Wand in the actual Body Shop environment. Primary emphasis was placed on the hard dollar ROI of the Wand. Hard Dollar ROI was defined as the Wand's ability to find "Hidden Damage" or under defined "Damage Severity" in the Repair Planning and Estimating Process, that was not later identified in any of the subsequent repair processes. This was regardless of the frustration, and inefficiencies associated with finding the damage later. The Wand information was captured in a Blind Study Format. Only the Matrix Staff would see the results, no estimators or repair technicians were allowed to see the data. This was established to ensure that we were isolating and measuring only Hard Dollar ROI.

However, we were very careful to internally track the intrinsic and secondary values of the Wand, outside of the normal study. The results are listed below.

Once again none of the secondary or intrinsic values counted toward Hard ROI value.

The Study

The 12 week study began in Oct. 2010 and ended February 1st, 2011, with 8 weeks of documented measuring. During this time 103 vehicles were measured, and tracked through the entire process. Maintaining the integrity of the blind study was at times difficult, knowing that the Wand Data could quickly solve many difficulties that came up in the repair process. This was true from the front of the shop to the back.

The Hard ROI Results

Of the 103 vehicles measured, it was discovered that 3 vehicles out of every 10 had hidden damage that went undetected. The undetected damage had an average time value of 3 hours. The 3 hours multiplied by the hourly rate of $60 per hour, equaled $180 per vehicle. Using the 3 vehicles out of 10 ratio, 30 total vehicles times $180 dollars equals $5,400. The annualized Hard ROI equals $5,400 divided by the 8 documented measuring weeks = $675 per week x 52 weeks = $35,100. The Body Shop receives 60% of each billable hour, total annualized Hard ROI is $21,060.

Secondary and Intrinsic Values Discovered

1. Vehicles are repaired faster (improved cycle times)
2. Hidden damage is found and documented up front
3. Damage severity is correctly determined
4. Provides repair blueprint
5. Appropriate structural repair hours are charged up front
6. Hours are locked into the estimate
7. Disputes concerning actual damage are eliminated
8. Full color 3-D Photo documentation of the damage and repairs (StAR report)
9. Zero supplements for structural damage
10. Predictive Wheel Alignment eliminates vehicle shuffle to and from the Alignment Facility
11. Vehicles are repaired correctly
12. Fewer Vehicles are unnecessarily totaled
13. Technicians and Body Shops get paid for the work they do, by merely identifying the complete damage up front, (this is literally found money)
14. Technicians avoid the frustration associated with hidden damage and severity
15. Technicians and Estimators have reduced conflict over appropriate repair hours
16. Technicians reduce trial and error associated with installing repair parts
17. Technicians have increased confidence in repairing hard hit vehicles
18. Insurance Adjuster travel is minimized
19. Insurance Company and Body Shop relations are eased with objective damage data
20. Insurance Companies can reduce paper work
21. Insurance Companies can give repair authorization quickly with full knowledge of structural damage
22. Insurance Companies can save money on Rental Car days
23. Vehicle owner and Body Shop relations are improved with full color 3-D Photo documentation of the damage and repairs
24. Vehicle owner and Insurance Company relations are improved with full color 3-D Photo documentation of the damage and repairs
25. Vehicle owner and Insurance Company are assured of Quality Repair
26. Vehicle owners can be assured of no diminished value with full color 3-D Photo documentation of the damage and repairs
27. The Perceived Value of Body Shop services are increased industry wide

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