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Forensic Photogrammetry: A Case Study

Posted on Monday, October 16th, 2017

Forensic Playground photo repaired

This is a guest article by forensic imaging consultant Michael Mayda. Michael is an expert witness specializing in photogrammetry and visibility analysis. He has been in business since 1977, and currently lives in Sacramento, California.   Why Use Photogrammetry in Forensics? Photogrammetry can be a very powerful tool in forensic analysis. It is often useful to have an accurate 3D reconstruction of an accident or crime scene, especially in cases where position, distance and perspective are important. Given the large number of photos taken at these scenes, photogrammetry can be a practical way for investigators, lawyers, and insurance adjusters to obtain better information. In addition, photogrammetry can be used to preserve or recover measurement data long after the on-scene investigation…Read More


Survey Grade Accuracy with a Drone without Ground Control !

Posted on Tuesday, November 8th, 2016

To get high accuracy with a drone photo-based survey, one usually needs to place and survey ground control points. Ground control points are either man-made targets (e.g. large cross) that you place on the ground before the flight, or visible natural features, surveyed with a high accuracy instrument (total station or RTK GPS). To achieve 2 cm to 4 cm ground accuracy from your drone survey over the whole area usually requires 10 or more ground control points. These ground control points (GCPs) require travel over the whole site, take time to place, survey, and optionally remove, and thus are an expensive method. Any way to reduce ground control requirements is money and time in your pocket! How can you reduce…Read More


Accuracy of Pile Volume Measurement with Photogrammetry

Posted on Monday, November 4th, 2013

Accurate volume measurement of piles of material is important in a number of applications, such as: stock pile inventory management, volumes of tailing piles, volume of organic materials in composting operations, quarry pit size, mine reclamation, etc. These piles are difficult to measure due to their size, difficulty of traversing, and non-uniform shapes. The advent of UAV (unmanned aerial vehicles) with cameras, and software for extracting surface shape from imagery, such as PhotoModeler, have greatly eased this task. A key factor in using this technology in real-world applications is volume accuracy. This article highlights a series of PhotoModeler Scanner experiments using SmartMatch and Dense Surface Modeling (DSM) to model a small sand pile with a known volume to gauge volume…Read More


Capturing Motion with Photogrammetry and PhotoModeler

Posted on Friday, October 11th, 2013

In this post I highlight the practical uses of PhotoModeler Motion (PMM), and feature two example projects. PhotoModeler Motion / PMM is the top of the PhotoModeler product line. It brings the time dimension into your measurement and modeling projects. PMM includes all features of PhotoModeler and PhotoModeler Scanner, and adds modeling of a dynamic object or scene over time – a PMM project encapsulates a series of mini projects – one per ‘epoch’, based on the frame rate of your photography or video. Some uses of PMM are a) measuring the effect of a load on a material over time, b) modeling the change in shape of an object or scene due to erosion or human action, or c)…Read More


Using the GoPro Hero 3 for 3D Photogrammetry Modeling and Measuring

Posted on Monday, September 23rd, 2013

  Introduction The GoPro Hero 3 is a small, lightweight, robust, low cost, and high definition video and still camera used primarily for capturing action.  The GoPro Hero 3 Black is one of the recent high resolution versions of the GoPro lineup that can be used for photogrammetry – the science of measurement, modeling and scanning using photographs. [Update: At the time of writing, the Hero 3 Black was the highest resolution available. Other improved versions are now available.] Due to the GoPro’s small size, low weight, wifi, and good image quality it is an interesting platform to consider for photogrammetry. On the other hand, a DSLR camera with a choice of lenses is the best choice for high accuracy photogrammetric…Read More


Photogrammetry helps police clear accident scenes quickly and safely

Posted on Wednesday, August 21st, 2013

Car accidents are an ordeal for everyone. They’re traumatic for the people involved, of course, but they also affect everyone else on the road. The more serious the incident, the more likely that multiple lanes will be blocked, and the longer it will take to get it cleared. The police officers at the scene have one of the most difficult jobs of all. They have to measure and map the scene and the vehicles in scrupulous detail so that the courts can get a clear picture of exactly what happened. To add to their challenge, they have to do all of this in the middle of a busy, backed up roadway. The Solution is Photogrammetry Fortunately, there’s an easier way…Read More


Camera Fundamentals and Parameters in Photogrammetry

Posted on Monday, July 29th, 2013

Photogrammetry is the science of using photographs to obtain measurements and models of real-world objects and scenes. Photogrammetric techniques involve using known information to help solve other, previously unknown information.  Several critical pieces of known information concern the camera used to capture the photographs, and defining those pieces in mathematical terms known as camera parameters. Photogrammetry uses the mathematics of light rays to build up knowledge of the geometry of the scene, its objects and the location of the camera when the photographs were taken. When light hits part of the scene, it is reflected toward the camera, passes through the lens, and is picked up by film or an electronic image sensor. Knowledge of the fundamental parameters of the…Read More


PhotoModeler’s Dense Surface Modeling Accuracy Study

Posted on Thursday, September 20th, 2012

  We have completed an extensive accuracy study of PhotoModeler’s 3d scanning capability called Dense Surface Modeling (DSM).  The full accuracy study article can be found here: Quantifying the accuracy of dense surface modeling within PhotoModeler Scanner. The article shows that PhotoModeler Scanner can match (if not exceed) the accuracy of a laser scanner. Using a laser scanned scene as a benchmark, PhotoModeler Scanner is able to reconstruct the same scene to within an error of 0.9mm at a 3.5m range. This is well within the distance error (+/- 2mm at 10m) of the laser scanner. PhotoModeler can provide the accuracy of a laser scanner with the cost, portability and convenience of photogrammetry (using your camera and software). This report…Read More


PhotoModeler – what’s in there?

Posted on Wednesday, February 1st, 2012

At Eos we like to think of PhotoModeler like an onion.  For many tasks you’ll find the standard operations, that are front and center, are all you need.  For other tasks you’ll discover that PhotoModeler offers a wealth of feature-rich layers, giving you the power to efficiently and accurately handle complex 3D measurement projects. Many of PhotoModeler’s features have been added over the 20 years since it was initially introduced – most as a result of user input and an understanding of what real-world projects our customers are carrying out.  We’ve created a new Comprehensive Feature List to help you learn about all of PhotoModeler features and benefits at a glance. We are peeling the onion for you! 


New PhotoModeler Geology Article

Posted on Friday, January 28th, 2011

A new journal article describes a technique using PhotoModeler for the measurement of inaccessible geological features. Details here – look for “Using Close Range Photogrammetry to Measure the Position of Inaccessible Geological Features”.


 


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