dental biometrics used in forensic science - Call for papers= Asian ...

More documents

Recommendations

Info

model. Atlas registration is used to give labeling or numbering to the teeth present in jaw, it will help in matching stage. Radiograph from database selected and this radiograph are preprocessed, segmented and contour extracted from it. Also registration of teeth is given as per atlas registration. And last stage of this system is matching, in this feature extracted from these two radiograph matched with each other using algorithm and final result is identification of person based on matching distance between radiographs[1] [5]. Radiograph Collection Radiograph segmentation Matching tooth contour Contour Extraction Dental work Extraction Atlas Registration Matching of Radiograph Fusion Subject Identification Fig.1 Block diagram of Dental Identification System 3. HUMAN IDENTIFIACTION BASED ON DENTAL RESTORATIONS Preprocessing and Segmentation: Dental radiograph initially converted into gray scale image. Region of interest (ROI) are decided on radiograph. Algorithm is used to determined gray threshold value of ROI. Then histogram is prepared for the grayscale threshold. To smooth the histogram filter is used to filter out unwanted intensities from image .After this gray image converted into binary image. Active contour model (Snake method) is used for segmentation of image [6] [15]. Dental Code: Dental code is used to locate teeth, size of teeth and distance between DR or teeth. Dental Atlas registration: Method or code is developed to locate teeth this is known as dental atlas registration. In this we can give numbering to teeth from left to right of jaw and also we can differentiate between upper jaw and lower jaw. As per [2], HMM and Markov model was used JERS/Vol.III/ Issue I/January-March, 2012/26-29 Journal of Engineering Research and Studies E-ISSN0976-7916 Matching dental work for this registration purpose. This registration will help in matching stage. Size of DR: The method uses to resize DR in same size. It means amount of pixels should be same for all DR. So it will help in matching. Distance between DR: This is more useful in matching stage to create more sensitive algorithm of matching. In this distance of neighboring teeth is calculated. Matching: After creation of dental code (DC) ,this DC will match to the DC of database radiograph and distance between this two DCs calculated. So finally we received matching percentage between the AM and PM radiograph. Based on result subject get identified [6] [15]. 2.1 Nomir & Adlab-Mottaleb In [2], Nomir & Adlab-Mottaleb introduce a fully automated approach for dental x-ray images. The technique depends on applying the following stages: iterative threshold to divide the image into two parts teeth & background, adaptive threshold in order to increase the accuracy and remove teeth interfering, horizontal integral part in order to separate the upper jaw and lower jaw, final, vertical integral projection in order to separate individual tooth. 3.2 Eyad Haj Said, Diaa Eldin M Nassar, Gamal Fabry & Hany Ammar In [3], Eyad Haj Said, Diaa Eldin M Nassar, Gamal Fabry & Hany Ammar presented method of teeth segmentation using mathematical morphology approach offers fully automated teeth segmentation and reduces segmentation error due to inherent to that improve the definition of teeth versus background and segmentation performance. 3.3 Supaporn Kiathsin, Adison Leelasantitham, Kosin Chamnogthai & Kohji Higuchi A match of x-ray teeth films using image processing based on special features of teeth by Supaporn Kiathsin, Adison Leelasantitham, Kosin Chamnogthai & Kohji Higuchi [4]. This method can help dentist to match simply pair of teeth using special features present on teeth film. This presents some steps: teeth’s picture is scanned and adjusted by scanner & computer, converted into binary code, and decoded in chain code (Direction code) 3.4 Hong Chen & A.K. Jain Dental biometry is used to identify human. In [5], Hong Chen & A.K. Jain introduced dental biometrics using active contour extraction model (ACM). In this they proposed a new dynamic energy term i.e. directional snake to extract contours of teeth. As per this paper traditional snake cannot able to discriminate edges of multiple adjacent objects. So there can be presence of overlapping images. To remove this problem Hong Chen & A.K. Jain utilized direction gradients. The contour extraction process having three steps: initialization- In this gum line is
used to separate the crown and roots of teeth for the snake initialization, convergence of Gradient, fine adjustment Hong Chen & A.K. Jain [6] presented Dental Biometrics: Alignment and Matching of Dental Radiographs. This proposed system has main two stages: feature extraction, matching. In this to extract contours of dental work the intensity histogram of the tooth image is automated with the mixture of Gaussian model. In the matching stage three steps given: Tooth level matching, tooth contours are matched using a shape registration method, and the dental work is matched on overlapping areas. Distance between postmortem and ante mortem radiographs provide candidates identities to estimate subject identification. Hofer M & Marana In [6], Hofer M & Marana AN presented Dental biometrics for human identification based on dental work. Dental biometrics used for forensic identification, in this dental work information is used to identify human. This paper three processing steps were given as per following: Segmentation (Feature Extraction), creation of dental code, matching Primarily segmentation is done by detecting threshold and finally snake (active contour model) algorithm used. Dental code is prepared as per the position, size of dental work and neighboring dental work. Matching done by editing distance between dental works. 4. DISCUSSION Dental biometry is used in forensic identification. Some other methods are also present for forensic identification. But it is more useful when there is no any other identity like iris [11], face, fingerprints [16] etc of victim remaining. Dental atlas can remain in well condition for some time period after the death of person so by taking radiograph at the time of PM and matching with it to database having with forensic department it can give you identification of victim or subject. Also dental biometry can be used in human identification system. Also matching of x-ray films which is the part of dental biometry can help dentist to their clinical diagnosis [1] [5]. Dental biometry requires AM and PM radiograph only for identification. Dental biometry cannot require additional information. DNA requires additional information of subject for identification. Dental biometry comes under physical biometry so it is easier to measure quantitatively as compared to behavioral biometry. Hand vein pattern and retina scan are physical biometry but it having low acceptability because it may reveal person’s health status and it is invasive method. In disasters, victim or subject’s physical characteristics like iris, face, fingerprints not available that time biometry related to these characteristic not worked. So there is then need of dental biometry because dental jaw JERS/Vol.III/ Issue I/January-March, 2012/26-29 Journal of Engineering Research and Studies E-ISSN0976-7916 remaining in well condition in massive disasters. Dental biometry is used for forensic identification. Also matching of dental radiograph can be used in clinical diagnosis forensic medicine (Forensic Dentistry) [1]. Dental biometry having some limitation based on below mentioned points so in some cases it is not good choice for identification: • Positive identification: AM and PM radiographs should have sufficient data to match, with no any discrepancy like missing tooth. • Possible identification: If consistent features are present in AM or PM radiograph but if there is problem in quality of either AM or PM radiograph then this may create no positive identification. • Insufficient evidence: Sufficient information is not available for the basis of conclusion. • Exclusion: The radiograph information is inconsistent [1]. 5. CONCLUSION Segmentation of Radiographs: A fast marching based algorithm is used to segment radiographs into homogeneous regions so that each region contains only one tooth [9]. This method utilizes the characteristics of dental radiographs in that soft tissue and bone have different pixel intensity. This method can be extended to analyze other types of radiographs. ASM-Based Tooth Contour Extraction: An active shape model (ASM) is used to extract tooth contours. The traditional ASMs have some problems that are solved by new ASM. Extraction of Contours of Dental Work: An anisotropic diffusion used to enhance the images and extract the contours of dental work with a reasonable assumption that pixel values of dental restoration follow a Gaussian distribution [1] [2] [3] [5] [10] [17]. Hybrid HMM/SVM Model for Representation of Dental Atlas: Tooth states in the HMM combined with SVMs model the shape of teeth, and distance states in the HMM model the inter-teeth distance caused by missing teeth. Construction of Observation sequences: An observation sequence is an alternating sequence of tooth shapes and distances between successive teeth. To compensate for the difference between image resolutions of AM and PM images, the tooth shapes are normalized to affixed width, and the distances between teeth are regularized with the width of neighboring teeth [1] [7] [17]. Location of DW (Dental Work) can be finding out by implementing algorithm. In this all DWs in the DWM from left to right based on the center of mass point of each individual DW sorted. This is requiring creating dental code. The upper jaw and lower jaw is identified by the valley location with respect to upper jaw and lower jaw [6] [15]. Matching of tooth contours: Tooth contours are open curves. To match tooth contours, correspondence between the tooth contours has to be established. An
Page 1: JERS/Vol.III/ Issue I/January-March

dental biometrics used in forensic science - Call for papers= Asian ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?