forensic facial reconstruction

Forensic Facial Reconstruction

- What is forensic art and forensic facial reconstruction?

- How are faces reconstructed from skulls and what are the problems associated with these methods?

- How can these methods be improved?

Forensic Art

“...forensic art is any art that aids in the identification, apprehension, or conviction of criminal offencers, or that aids in the location of victims or identification of unknown deceased persons.”

- Karen Taylor, Forensic Art and Illustration, 2001


Forensic facial reconstruction relates specifically to the identification of unknown deceased individuals. Images are produced by a forensic artists from post-mortem photographs of fleshed individuals or from the skulls of skeletonized individuals.


This technique does not directly result in a court admissable identification. It is a recourse when there is potential to identify the individual, such as DNA or dentition, but there are no possibilities to compare it with.

The reconstructed face is publicized in the hopes that someone will recognize the indivdual and come forward with a possible identity.


This technique works because of our ability to recognize and recall faces. We can recognize a face with a remarkably small amount of information. The trick is to present that amount of information without adding too much inaccuracy or not providing sufficient context.


The artistry of forensic facial reconstruction is to create a human face from limited soft tissue or skeletal data.

There is no way to fully erradicate bias from scientific work. In the case of facial reconstruction, however, some artistic and human bias is needed in order to create a recognizable face.

Facial reconstruction from the skull

2D methods Drawing an overlay on a 2D image of the skull

with or without tissue depth marker 3D methods

Placing tissue depth markers on the skull and sculpting the face directly over these markers

Computing methods Scanning in a 3D image of the skull and using a

program to build up a face on it

American Method

Karen Taylor Place tissue depth markers on the skull and then

photograph it The markers are then foreshortened The face is drawn over top of this image Bypasses the time-intensiveness of modelling

directly on the skull

American Method

From Wilkinson 2004

Manchester Method

Soft tissue depth measurements are placed directly on the skull or skull cast. The facial muscles are modelled in using clay, followed by a thin layer of clay representing skin.

This method is very time consuming. Even though it produces a 3D image, when it is

photographed it is just reduced to a 2D image again.

Manchester Method

From Wilkinson 2004

Soft tissue depth

There are standardized depths for the soft tissue of human skulls depending on the age, sex, ethnicity and weight of the individual.

These depth measures correlate to specific locations on the skull.

Facial tissue measurement locations

Tedeschi-Oliveira et. al. 2009

Methods of measuring soft tissue

Prior to the advent of MRI, ultrasound, and computing tomography (CT scan) technology, soft tissue depths were taken using simple needles on cadavers.

While the measurements from this technique are close to those from modern techniques, there is some distortion associated with taking measurements from cadavers.

Skin begins to lose moisture very quickly. Gravity distorts features.

Methods of measuring soft tissue

From Wilkinson 2004

Modern methods of soft tissue measurement

Combination of skull information from CT scans with holographic topography (Prieels et. al. 2009)

Modern methods of soft-tissue measurement

Measurements and categorization done from x-rays (Utsuno et. al. 2007)

Modern studies on soft tissue measurement

Caucasian (De Greef et. al. 2006)

Japanese (Utsuno et. al. 2005, 2007, 2010)

North-Western Indian (Sahi et. al. 2008)

Portuguese (Codinha 2009)

Brazilian (Tedeschi-Oliveira et. al. 2009)

More age, sex and BMI specific (De Greef et. al. 2009)

Continuing Problems

It is still difficult to estimate soft tissue features like nasal width, eyelids, and mouth width from the skull.

There are some formulas, but they have been found to be somewhat inaccurate and are dependent on knowing the individual's ethnicity.

This is further complicated by mixed race individuals.

Soft tissue in mixed race individuals

Philips and Smuts (1996) in particular found that South Africans with both white and black ancestry differed in very specific ways from the standard tissue depth measurements and other formulas presented for solely Caucasian or solely African individuals.

Computing Methods

There have been computer reconstruction models for forensic facial reconstruction since 1980.

There are numerous programs and systems, some outdated, some not.

Computing Methods

Wilkinson's (2004) specifications for an ideal computer program of this nature are:

1) The collection of information from the unidentified skull by scanning equipment.

2) The addition of such characteristic details of the unidentified individual such as age, sex, ethnic group and stature.

3) The production of the facial reconstruction.

Computing Methods

From Wilkinson 2005

Computing Methods There is a uniform or standard 'face' in the program

that is manipulated to fit the scanned in image of the skull. The measurements of this face are based on the same soft tissue depth measurements used in the other reconstruction methods.

Depending on the program, there may be a different standard face for various ages, sexes, ethnicities, and weights, ie) Caucasian male of average weight aged between 35 and 55 years.

The resulting image is usually black and white and lacks features like hair, open orbits, skin shading, etc.

From Wilkinson 2005

Computing Methods

At its most basic, these computer programs are no different from the manual reconstruction approach.

It does remove the possibility of human error in regards to the depth of the tissue markers.

It is more standardized in regards to marker locations.

It is much faster than either 2D or 3D reconstruction techniques.

Computing Methods vs Manual Methods

The only comparative study between computer and manual reconstructions was done in 1989 (Vanezis et. al.). The findings were that the manual reconstructions were slower, but more recognizable.

Obviously computer systems have changed drastically since then.

Vanezis et. al.'s advice to involve experienced forensic artists in the appraisal and alteration of the finished computer generated face is still valid.

Efficacy of Computing Methods

Wilkinson et. al. (2006) is one of the more recent studies of the recognizability of computer generated images.

Using Rapidform ™ a face was reconstructed from a skull whose original face was known.

Volunteers were shown a series of faces, one of which was the original face. They were then shown an image of the Rapidform ™ face and asked which non-reconstructed face it most resembled.

Efficacy of Computer Modelling

Of all the volunteers, 69.2% correctly chose 'D' as the original male face and 71.2% correctly chose 'B' as the original female face.

The program was also found to be very easy to use. Several people tried the program and those completely inexperienced with Rapidform ™ were able to produce a reconstruction very similar to those produced by experienced users.

Testing Computing Models

However, very few of the computing models in existence have been tested as extensively.

Most of the tests come from prior to 2000.

Conclusion

The methods used now are relatively successful. When they are not successful, it is very difficult to say why.

Were the tissue depth measurements inaccurate? Was the artist too inexperienced? Was the individual's skull not 'unique' enough? Was the reconstruction not seen at the right time and

right place by the right person?

As forensic scientists we can create accurate databases of soft tissue facial measurements and improve the skills of forensic artists.

It is also necessary to improve current facial reconstruction computer systems through comparative studies.

The success of computerized reconstruction depends on the integration of forensic artistry techniques into the program, or throught the involvement of forensic artists themselves.

forensic facial reconstruction

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