Forensic Artists Research Articles

Variaciones en el campo visual del espacio de trabajo del artista forense, durante la realización de retratos hablados mediante video llamadas: proyecciones para Chile y América Latina

Introducción: este artículo expone los resultados de un estudio ya finalizado, cuyo objetivo consistió en determinar si, durante la realización de retratos hablados a través de videollamadas, es posible evidenciar una correlación entre la amplitud del campo visual que tiene el testigo o víctima respecto del espacio de trabajo del artista forense, y el parecido resultante entre el retrato y el rostro de la persona a identificar.
 Enfoque: el énfasis está puesto en la aplicabilidad de estos nuevos medios tecnológicos en el contexto latinoamericano, particularmente hacia la superación de las distancias físicas existentes entre las víctimas y autoridades judiciales de algunos países de la región.
 Metodología: un primer grupo de 24 personas voluntarias situadas en Santiago de Chile tomó parte de entrevistas cognitivas individuales con un artista forense instalado en Dundee (Reino Unido) mediante videollamadas, 24 horas después de haber observado brevemente la fotografía de uno de los personajes de una serie de TV británica no transmitida en Chile. Durante las entrevistas, 12 de ellas tuvieron acceso visual a la imagen del tronco superior del artista y su espacio de trabajo, mientras que las otras 12 solo observaron en la pantalla una muralla blanca. Posteriormente, un segundo grupo de 24 personas, también ubicadas en Chile, evaluó el parecido de los retratos con respecto a las imágenes originales mediante una escala Likert.
 Resultados: los datos obtenidos sugieren que no existe correlación directa entre las variables consideradas, lo cual implica que los cambios en el entorno de realización de las entrevistas no tendrían un efecto significativo en la composición de los retratos.
 Conclusión: la ilusión de copresencia parece no ser imperativa para la creación de rapport entre el entrevistado y el artista forense.

Face recognition from multiple stylistic sketches: Scenarios, datasets, and evaluation

Due to the great texture discrepancies between photos and sketches, matching face sketches against mug shot photos is a challenging yet important topic in face recognition community, with potential applications in law enforcement and security. Despite the great progress achieved in recent years, existing works mainly focus on face recognition from SINGLE sketch. However, in real-world applications it is more practical to obtain MULTIPLE stylistic sketches for recognizing the suspect, such as clue from multiple eyewitnesses, cooperation with multiple forensic artists, even drawn with different kinds of pencils. It is challenging due to the difficulty of taking multiple sketches into consideration in these scenes. To this end, we present a comprehensive investigation of face recognition from multiple stylistic sketches. Considering that there are two types of sketches available, i.e. hand-drawn sketch and composite sketch, we propose three specific scenarios: (1) recognition from multiple hand-drawn sketches, (2) recognition from both hand-drawn sketch and composite sketches, and (3) recognition from multiple composite sketches. In additional to the definitions of the proposed scenarios, we also provide evaluation protocols and benchmark performance on public available datasets. Through extensive experiments on benchmarks, plenty of challenges in proposed scenarios are finally discussed and there are many possible future directions worth further investigation. The main purpose of this paper is to open a first fundamental study on the topic of face recognition from multiple stylistic sketches. Possible high technical and superior methodologies are encouraged in the future. Related materials of this paper are publicly available at http://chunleipeng.com/FRMSketches.html.

Robust face pseudo-sketch synthesis and recognition using morphological-arithmetic operations and HOG-PCA

In this paper, we propose a simple but yet effective method for synthesizing a pseudo face sketch (pseudo-sketch) from a photo, to be used for face recognition based on sketches drawn by a forensic artist. In contrast to current methods, the proposed method does not require training samples while fairly maintains the salient facial features as the artist do. We also propose a matching method on the basis of the Histograms of Oriented Gradients (HOG) descriptor and Principal Component Analysis (PCA), called HOG-PCA, to handle the similarities between a forensic sketch and a synthesized pseudo-sketch. In this method, we first extract the HOG features for the sketch and pseudo-sketch at regular grid and overlapped patches. The PCA is then applied to address the redundancy in feature representation due to several overlapped patches. Finally, the Nearest Neighbors Classifier (NNC) with the cosine distance is used to classify the sketch and pseudo-sketch pairs as matched or mismatched. Experimental results on CUHK and AR face sketch databases demonstrate that our proposed methods outperform state-of-the-art methods.

Interactive Evolution of Facial Composites

Facial composite is a tool used in criminal investigation to identify an unknown person, usually a suspect of a crime. Traditionally, it is created by a forensic artist on the basis of a detailed description provided by one or several eye witnesses. Due to the subjectivity and low efficiency of the composition process, facial composite has not been considered to be a reliable evidence until recently. Despite expectations, replacing traditional drawing by computer-driven systems did not result in improved identification rates. Therefore, the research of the last decades has been oriented on developing a method more compatible with the human way of perceiving faces. In this paper, we present a system developed as a result of deep psychological research on human face perception and recall. The proposed approach enables automatic generation of facial images and their presenting to a witness, resembling the process of line-up identification. Besides providing information on computational model of a face, the primary goal of the paper is to discuss the applied evolutionary strategies in terms of individual parameter settings and evolutionary operator choice and to evaluate the strategies with regard to the construction time, operator usability and composite accuracy. Besides, we summarize the procedures recommended for further improving the efficiency of the composition process.

When age-progressed images are unreliable: The roles of external features and age range

When children go missing for many years, investigators commission age-progressed images from forensic artists to depict an updated appearance. These images have anecdotal success, and systematic research has found they lead to accurate recognition rates comparable to outdated photos. The present study examines the reliability of age progressions of the same individuals created by different artists. Eight artists first generated age progressions of eight targets across three age ranges. Eighty-five participants then evaluated the similarity of these images against other images depicting the same targets progressed at the same age ranges, viewing either whole faces or faces with external features concealed. Similarities were highest over shorter age ranges and when external features were concealed. Implications drawn from theory and application are discussed.

Forensic facial approximation assessment: can application of different average facial tissue depth data facilitate recognition and establish acceptable level of resemblance?

Facial soft tissue thicknesses (FSTT) are important guidelines for modeling faces from skull. Amid so many FSTT data, Forensic artists have to make a subjective choice of a dataset that best meets their needs. This study investigated the performance of four FSTT datasets in the recognition and resemblance of Brazilian living individuals and the performance of assessors in recognizing people, according to sex and knowledge on Human Anatomy and Forensic Dentistry. Sixteen manual facial approximations (FAs) were constructed using three-dimensional (3D) prototypes of skulls (targets). The American method was chosen for the construction of the faces. One hundred and twenty participants evaluated all FAs by means of recognition and resemblance tests. This study showed higher proportions of recognition by FAs conducted with FSTT data from cadavers compared with those conducted with medical imaging data. Targets were also considered more similar to FAs conducted with FSTT data from cadavers. Nose and face shape, respectively, were considered the most similar regions to targets. The sex of assessors (male and female) and the knowledge on Human Anatomy and Forensic Dentistry did not play a determinant role to reach greater recognition rates. It was possible to conclude that FSTT data obtained from imaging may not facilitate recognition and establish acceptable level of resemblance. Grouping FSTT data by regions of the face, as proposed in this paper, may contribute to more accurate FAs.

Forensic sketch recognition using user specific facial region

Forensic sketches play an important role in criminal identification process. These sketches are drawn by forensic artists on the basis of the description provided by an eyewitness or victim. These sketches are publicised to get some clues to reveal the identity of the criminals. A faster way to identify the criminals is to match the forensic sketch with some government agency mug-shot database. In the process of drawing a sketch, the description provided by the eyewitness often includes some unique facial details comprising the deviations from an average face. For example, some spot on face, mole, scar, cuts, etc. Study says that, the information which is more uncommon is more likely to be last in the memory. In this paper, we suggest a sketch to mug-shot matching approach called difference vector-based matching DVBM, which utilises deviations present in facial regions to measure the similarity between a sketch and a mug-shot image. The method is tested over a dataset containing 112 sketches and a large mug-shot gallery of 7,112 images. The results generated using DVBM are compared with standard face matcher and show considerable improvement in matching accuracy.

Soft tissue thickness values for black and coloured South African children aged 6–13 years

In children, craniofacial changes due to facial growth complicate facial approximations and require specific knowledge of soft tissue thicknesses (STT). The lack of South African juvenile STT standards of particular age groups, sex and ancestry is problematic. According to forensic artists in the South African Police Service the use of African–American values to reconstruct faces of Black South African children yields poor results. In order to perform a facial approximation that presents a true reflection of the child in question, information regarding differences in facial soft tissue at different ages, sexes and ancestry groups is needed. The aims of this study were to provide data on STT of South African Black and Coloured children and to assess differences in STT with respect to age, sex and ancestry. STT was measured using cephalograms of South African children (n=388), aged 6–13 years. After digitizing the images, STT measurements were taken at ten mid-facial landmarks from each image using the iTEM measuring program. STT comparisons between groups per age, sex and ancestry were statistically analyzed. The results showed that STT differences at lower face landmarks are more pronounced in age groups per ancestry as opposed to differences per age and sex. Generally, an increase in STT was seen between 6–10 year old groups and 11–13 year old groups, regardless of ancestry and sex, at the midphiltrum, labiale inferius, pogonion, and beneath chin landmarks. This research created a reference dataset for STT of South African children of Black and Coloured ancestry per age and sex that will be useful for facial reconstruction/approximation of juvenile remains.

Modelling of facial growth in Czech children based on longitudinal data: Age progression from 12 to 15 years using 3D surface models

Dealing with the increasing number of long-term missing children and juveniles requires more precise and objective age progression techniques for the prediction of their current appearance. Our contribution includes detailed and real facial growth information used for modelling age progression during adolescence. This study was based on an evaluation of the overall 180 three-dimensional (3D) facial scans of Czech children (23 boys, 22 girls), which were longitudinally studied from 12 to 15 years of age and thus revealed the real growth-related changes. The boys underwent more marked changes compared with the girls, especially in the regions of the eyebrow ridges, nose and chin. Using modern geometric morphometric methods, together with their applications, we modelled the ageing and allometric trajectories for both sexes and simulated the age-progressed effects on facial scans. The facial parts that are important for facial recognition (eyes, nose, mouth and chin) all deviated less than 0.75mm, whereas the areas with the largest deviations were situated on the marginal parts of the face. The mean error between the predicted and real facial morphology obtained by modelling the children from 12 to 15 years of age was 1.92mm in girls and 1.86mm in boys. This study is beneficial for forensic artists as it reduces the subjectivity of age progression methods.

If I Had Possession over Judgment Day: Augmenting Robert Johnson

If I Had Possession over Judgment Day: Augmenting Robert Johnson

Producing facial composite sketches in remote Cognitive Interviews: a preliminary investigation

Justice systems around the world are increasingly turning to videoconferencing as a means to reduce delays and reduce costs in legal processes. This preliminary research examined whether interviewing a witness remotely – without physical co-presence of the witness and interviewer – could facilitate the production of quality facial composite sketches of suspects. In Study 1, 42 adults briefly viewed a photograph of a face. The next day they participated in Cognitive Interviews with a forensic artist, conducted either face-to-face or remotely via videoconference. In Study 2, 20 adults participated in videoconferenced interviews, and we manipulated the method by which they viewed the developing sketch. In both studies, independent groups of volunteers rated the likeness of the composites to the original photographs. The data suggest that remote interviews elicited effective composites; however, in Study 1 these composites were considered poorer matches to the photographs than were those produced in face-to-face interviews. The differences were small, but significant. Participants perceived several disadvantages to remote interviewing, but also several advantages including less pressure and better concentration. The results of Study 2 suggested that different sketch presentation methods offered different benefits. We propose that remote interviewing could be a useful tool for investigators in certain circumstances.

Forensic Face Sketch Recognition Using Computer Vision

Now - a - days need for technologies for identification, detection and recognition of suspects has increased. One of the most common biometric techniques is face recognition, since face is the convenient way used by the people to identify each - other. Understanding how humans recognize face sketches drawn by artists is of significant value to both criminal investigators and forensic researchers in Computer Vision. However studies say that hand - drawn face sketches are still very limited in terms of artists and number of sketches because after any incident a forensic artist prepares a victims sketches on behalf of the descripti on provided by an eyewitness. Sometimes suspects used special mask to hide some common features of faces like nose, eyes, lips, face - color etc. but the outliner features of face biometrics one could never hide. In this work, I concentrated on some specific facial geometric feature which could be used to calculate some ratios of similarities from the template photograph database against the forensic sketches. This paper describes the design of a system for forensic face sketch recognition by a computer visi on approach like Two - Dimensional Discrete Cosine Transform (2D - DCT) and the Self - Organizing Map (SOM) Neural Network simulated in MATLAB.

Facial soft tissue thicknesses of the mid-face for Slovak population

Forensic facial approximation is used as a tool for recreating the antemortem appearance of unknown dead and thus facilitates their identification. Several approaches to facial approximation are based on data on facial soft tissue thicknesses (FSTTs). The availability of sex-, age- and population-specific data contributes to the accuracy of the resulting facial approximation model. In this paper, first data set on FSTTs for a Central European population are presented. Soft tissue thicknesses of the mid-face were measured on 160 head CT-scans of 80 males and 80 females aged from 18 to 87 years. These CT-scans were made available after being a part of the diagnostic procedure concerning the paranasal sinuses of the patients. Basic descriptive statistics (i.e. mean, SD, median, range) for the FSTTs at 14 facial landmarks is reported separately by sex and age. Such information allows the forensic artist to choose the most suitable values for the FSTT considering the previous physiological and osteological analysis of the human remains.

Computer assisted age progression

A computer assisted method for altering the perceived age of a human face is presented. Our technique is based on calculating a trajectory or axis within a multi-dimensional space that captures the changes in large scale facial structure, shading and complexion associated with aging. Fine facial details associated with increasing age, such as wrinkles, are added to the aged face using a variation on a standard image processing technique called high boost filtering. The method is successfully applied to two-dimensional photographic images exhibiting uncontrolled variations in pose and illumination. Unlike our previous work on automated age progression, here the objective is to allow a certain degree of manual control over the process by the adjustment of three key progression-control-parameters. In the future this work may form the basis for a software tool to be used by forensic artists.

Facial Geometry: Graphic Facial Analysis for Forensic Artists

Facial Geometry: Graphic Facial Analysis for Forensic Artists

Creating Face Models from Vague Mental Images

Abstract We present a novel approach to create plausible 3D face models from vague recollections or incomplete descriptions. This task plays an important role in police work, where composite facial images of suspects need to be created from vague descriptions given by the eyewitnesses of an incident. Our approach is based on a morphable model of 3D faces and takes into account correlations among facial features based on human anatomy and ethnicity. Using these correlations, unspecified parts of the target face are automatically completed to yield a coherent face model. The system uses a novel paradigm for navigating face space and provides high‐level control of facial attributes as well as the possibility to import facial features from a database. In addition, the user can specify a set of attribute constraints that are used to restrict the target face to a residual subspace. These constraints can also be enforced on the example faces in the database, bringing their appearance closer to the mental image of the user, and thus avoiding confusing exposure to entirely different faces. We also propose a novel approach for adapting the system to local populations based on additional image databases that are converted into our 3D representation by automated shape reconstruction. We demonstrate the applicability of our system in a simulated forensic scenario and compare our results with those obtained by a professional forensic artist using state‐of‐the‐art software for creating composite images in police work. Categories and Subject Descriptors (according to ACM CCS): I.3.6 [Computer Graphics]: Methodology and Techniques—Interaction techniques I.4.10 [Image Processing and Computer Vision]: Image Representation—Hierarchical, Multidimensional, Statistical J.m [Computer Applications]: Miscellaneous—Forensic Sciences

Facial Reproduction using Endodontic K-Files to Establish Anterior Tooth Position

ABSTRACTIn June 1993, a Cessna 404 aircraft crashed and burned at Hassai Airstrip, Sudan while attempting an emergency landing. Eleven people on board were killed. The remains of E.H., a driller from Burnaby, B.C., Canada, were identified by local authorities and repatriated to Canada for burial. Dental examination of the body by Canadian experts revealed many gross discrepancies compared to antemortem records of the alleged decedent. Therefore, this could not be the body of E.H. Through the efforts of a British Columbia coroner, it was suspected that the body of a Sudanese national had been substituted. Fragments from burned and traumatically fractured upper and lower front teeth in the body sent to Canada were reconstructed by an odontologist using endodontic (root canal) K-files. This allowed a dental technician to simulate the dental appearance and a forensic artist to complete a facial reproduction based on photographs of the skull. This reproduction will be presented to foreign authorities to gain p...