Forensics Tutorials and Videos

Various techniques in public safety, accident reconstruction and forensics.


Accident Reconstruction

Dealing specifically with vehicles and crashes.

Car Crush

Measure the crush of a vehicle from photos taken by an unknown camera, using an exemplar vehicle.

Crush from an Exemplar

Measuring the crush of a vehicle from photos of an unknown source by adding them to a solved project of an exemplar and freezing the points.

Image Sequences

How to use image sequences to track the location of a vehicle over time.

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Road Diagram

Creating a diagram of a road scene using multiple photos and a calibrated camera.

Road Single Unknown Photo

Creating a diagram of a skid mark on road surface from a single camera of unknown origin with control points.

 
 
 
 

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Single photo security camera

Examples of projects and features useful for forensic cases

Single Photo Security Camera

Getting measurements from a single security camera with high lens distortion. Describes steps-by-step, and how to quality checks.

Combining LIDAR (Laser scan) data with photogrammetry

The video outlines how PhotoModeler can use a laser scan of a crime scene to solve and extract information from a security / surveillance camera.

Determining a suspect's height from an unknown surveillance camera

Using PhotoModeler, a suspect's height can be measured from a single photo from an unknown camera. This technique shows the use of control point data to solve the camera position. This video shows one of the techniques described in the KB article "Using offset points for forensic height".

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Features

Useful and interesting features of PhotoModeler that are used in Forensics projects.

Measure

Demonstrates how to use the Measure pane. Display various types of measurements of objects and between objects.

Extending cylinders, lines or edges and measuring their intersection point

PhotoModelers cylinders, lines and edges all have a property that allows the 3D view to extend their length allowing for visualization of intersections. Additionally, selecting multiple objects calculates their closest intersection point.

Scale / Rotate / Translate

Use of the 'Imports and Coordinate Systems' tool to set up Scales, Rotations, and Translations.

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Leveling a project to gravity

Using a plumb line PhotoModeler projects can be leveled to gravity to perform slope and Z offset calculations.

Using Image Enhance

The Image Enhance pane can be used to bring out details that are hard to see. Adjust the image contrast, brightness or gamma to improve visibility of key details and help improve marking.

Dimensions

How to create annotation text and dimension lines on photographs.

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Aligning photos in 3ds Max

Accurate camera alignment can be achieved in 3D Studio Max using photogrammetry. PhotoModeler outputs full camera positions and matching image planes. The optional idealize stage remaps the images to account for lens distortion, improving the alignment.

 
 
 
 
 
 
 
 

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Background

Basic introductory topics useful for those working on Forensics projects.

User Interface Overview

Covers PhotoModeler's interface, Ribbon, status bar, and Windows pane interface, and customization.

Manual Points Project

For manual marked projects (or when you need to add manual marks and references to an automated project). Covers completing a simple manual points-based project start to finish.

Calibration Multi-sheet

How to pre-calibrate a camera for the most accurate results. Solving for focal length, principle point, and lens distortion.

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Tip Videos

Various interesting short tip videos that apply to Forensic work.

Troubleshooting high residuals

High mark residuals are often caused by incorrect references. This video outlines a way to find incorrect references in a manually marked PhotoModeler project.

Referencing

Demonstrates Referencing (manually matching points and objects that are marked on different photos) with more detail than the Manual Points Project.

Point Review Mode

Point Review Mode is a great way to examine the location of a point across all photos it is marked on. Selecting a point shows a zoomed in view of all photos the point is marked on in the Point Review pane.

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Printing and saving photos with markings

How to print a photo (or save to an external image) along with its markings, dimensions, 3D data and/or various zoom settings.

 
 
 
 
 
 
 
 

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