GB2305238A

GB2305238A - Forensic scanning system

Info

Publication number: GB2305238A
Application number: GB9516563A
Authority: GB
Inventors: Malcolm Brian Russell
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-12
Filing date: 1995-08-12
Publication date: 1997-04-02
Also published as: GB9516563D0

Abstract

A forensic scanning system for detection, measurement and recording of impressions or marks, such as footprints or tyre marks, comprises a scanner body A provided with supporting legs B, a light source C, an X-Y traction unit F, a signal-producing measuring device D borne by the X-Y traction unit, a camera E, and a control panel G. Signals from the signal-producing measuring device are output through output means H to a computer or other signal-processing means which can reconstruct a 3 dimensional image of the impression or mark and analyse the data by image processing techniques such as edge detection, surface smoothing and histogram flattening. Preferably the signal-producing measuring device D is a laser, an ultrasound generator or a video system which scans the surface in a raster pattern to derive the depth, width and length of the impression or mark. The data can be compared to a database of known features such as types and sizes of shoes and tyres.

Description

PATENT APPLICATION FOR A FORENSIC SCANNING SYSTEM This application is for a system of detection, measurement and recording of impressions or marks (footprints, tyre prints etc in surfaces like soil, sand, mud, grass, carpets etc ).

Current forensic methods of mark analysis use a varitaty of systems which contnbute delays in the time taken to identw whether an impression or mark found at the scene of a crime is relevant to the police investigation or not The system discnMed in this patent application speeds up the process by the use of high accuracy measurement systems and modern computer software.

SEE Visual No 4 Elements of the system: a: Scanner body b: Supporting legs always set to minimum c: Lighting d: Lasers e: Camera f: XY Traction Unit g: Control panel h: Interconnection Cable or other communication system The forensic scanning system is positioned above the impression or mark to be analysed. This could be a footprint, shoe print etc (see diagram 2). A purpose-built measuring device like a laser, ultrasonic detector or video measuring system with a variable focal length to suit the topography of the application, will scan the surface of the image in a rester scan pattern relarive to a datum point to derive the depth, width and length of the impression or mark.

As an example of the device in operation, this discription will use a laser measuring device and it could be equally replaced by either an ultrasonic system or video system in the discription.

The Output signal of the laser or lasers mounted in the scanning system is a stream of electrical analogue signals. These are converted via a high performance digital to analogue converter into a digital signal in order that the computer either a portable or a custom build controller can process this information.. This digitised data will then be sent via a interface protocol like RS232 or a PCMCIA to a controller card connected to a laptop computer and will be received by programmed software which will analyse the data from the impression or mark. The software will receive the laser's input in the form of floating point numbers which will represent the distance of the impressiom or mark's surface from the laser. These floating point numbers would correspond to the analogue depth measurements obtained by the laser.

Because the laser is taking measurements at very fine intervals it is possible to construct a 3 dimensional electronic picture of the impression or mark from the depth measurements. The data can then be analysed using AI (Artificial Intelligence) techniques and specifically image processing techniques such as edge detection, surface smoothing and histogram flattening.

Following some simple questions and answers by the operator onto the controllers screen , or by pattern recognition software built into the system, it is possible that the software could identify the impression Yb xcompanng the data against templates stored in a database. The templates in this database could be imprints of various makes of shoes, trainers, tyres or other objects of potential interest, which have been created previously. The imprint from the impression or mark would then be compared against the templates in the database to try and find a template which the imprint closely matched. Another technique that could be applied is feature matching.This would involve identifying certain features of the object such as size of shoe (which could be identified from the laser readings), width, or grip and comparing these features to features of shoes etc. in a database. The software could further analyse the object and identify a model of tyre or identify whether the foot print was from a trainer or a shoe for instance. With the database of templates and/or features it may be possible to identify who manufactured the shoe or trainer. All these techniques would help to identify the impression under consideration and would in effect produce a three dimensional image of the impression under investigation.

The software could also produce a three dimensional graphical representation of the object on a computer screen. This would enable the operator to zoom into an area of interest, rotate the imprint or take a slice of the object and see all these images at the location of the impression or mark.

A typical application would be at a scene of a police investigation where a scene of crimes officer would use this equipment to record an impression of a shoe, footprint, or tyre mark which was needed for evidence in a criminal investigation. At the scene of a crime the laser scanning device would be placed over the object and the laser would take measurements of the impression. These measurements would be translated into digital signals and scaled by the software in a laptop computer or controller in order that factual evidence can be given quickly to the investigating officers. The data could be compared against the database held on a laptop computer or sent via telephone lines to the regional forensic department where a more powerful computer could carry out all the database comparisons on the impression or mark, in order to identify it. In situations where the scene of the crime is not within access to a terrestial land line telephone, the data could be sent through a modem connection to a mobile telephone.

Once the data had been received at headquarters the impression or mark would then be analysed using the AI techniques mentioned earlier.

The result would be a very accurate mapping of such impression or marks that are found at scene of a crime and a decrease in the time which is normally expected from the current method of plaster cast impressions and other manual measurement techniques.

Attached are other visual's numbered 1,2,3 and 5 which show typical configuration for a laser based system from different views and and the interconnection of the main elements when used by a police scene's of crime officer.

Claims

1. A forensic scanning system for detection, measurement and recording of impressions or marks, which system comprises a scanner body provided with supporting legs, a light source, an X-Y traction unit, a signal-producing measuring dcvice borne by the X-Y traction unit, a camera, and a control panel, output means being provided to output signals irom the signal-producing measuring device to a computer or other signal-processing means.

2. A system according to Claim 1, in which the signal producing measuring device comprises a laser.

3. A system according to Claim 1, in which the signal producing measuring device comprises an ultrasound generator.

4. A system according to Claim 1, in which the signal producing measuring devices comprises a video system.

5. A system according to any one of the preceding claims, which is connected to a computer to construct a three dimensional electronic picture of the impression or mark from the measurements produced by the measuring device.

6. A system according to Claim 5, wherein the computer includes sofiware to permit zoom operations, rotation operations or slicing operations on the picture of the impression or mark.

7. A system according to Claim 5 or 6, which includes means whereby the picture of the impression or mark can he compared against a database of pictures of impressions or marks.

A A forensic scanning system for detection, mcasurement and recording of impressions or marks, substantially as hereinbefore described, with reference to the accompanying drawings.

9. A method ol forensic detection, measurement and recording of impressions or marks, which method comprises scanning a said impression or mark by means ofa signal-producing measuring device horne hy an X-Y traction unit, outputting the signals produced hy the signal-producing measuring device to a computer or other signal-processing means and generating a three dimensional electronic picture of the said impression or mark.

10. A method according to Claim 9, wherein a laser measuring device is employed as the signal producing measuring device.

11. A method of li,rcnsic detection, measuremcnt and recording of impressions or marks, substantially as hereinbefi,re described, with reference to the accompanying drawings.