Toward Development of a Forensic Visualization Lifecycle Management System
I. Fujishiro1, K. Ueda1, X. Mao2, M. Toyoura2, A. Sugiura2, Y. Takeshima3, T. Hayase3
1 Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan
2 Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu 400-8510, Japan
3 Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japanfuji@ics.keio.ac.jp
ABSTRACTIn this project, we are going to develop a forensic visualization lifecycle management system, where leading-edge informatics technologies, suchas provenance management, augmented reality and affection estimation, are integrated to allow the users with different roles to visualize
investigated crime data in a first-person manner for clarifying points of dispute in court. In this first-year report, we place a particular focus on
realtime 3D simulation of bleeding as an integral part of functionalities to be provided by the developed system.

1. Introduction
We build upon a commonly-used Lagrangian
method, called SPH (Smoothed Particle Hydrodynamics) to faithfully simulate bleeding on human skinsurface, which is inevitable to reproduce stabbing
incidents from investigation information.
Salient features of the SPH simulation are three-fold:(1) bleeding from wounds modeled along with in vivo
blood flow reflecting their geometry;(2) congelation of blood represented by varying
viscosity according to the time exposed to the air;
(3) adherence to the skin surface formulated by anadditional adsorption term due to van der Waals
force introduced to the original Navier-Stokes
equations.
2. Methods
2.1 Bleeding from wound
The shape of a wound on the skin surface is definedby user-input strokes, and its depth and width are
determined automatically by the type of estimated blade.
Then, a simple in vivo blood flow model (Fig. 1) isevaluated within the resulting prismoid, where anacceleration is directed in parallel to the skin surface
normal. When colliding with an exit polygon, theparticle bleeds.

Fig. 1

A simple in-vivo blood flow model.

2.2 Congelation of blood
After bleeding from the wound, blood starts tocontact with the air and clot through the action ofplatelets. This phenomenon can be represented bychanging the viscous force of each particle of the blood
according to the time exposed to the air, as shown in Fig.
2. Any particle can be classified into the three phases
depending on the distance from the blood surface ateach time step, and a particle closer to the surface ismodeled to clot faster by moving forward its
congelation timer.

(a) time-varying viscosity(b) particle class

Fig. 2 Changing viscosity of particle
according to the degree of exposition to the air.
2.3 Adherence to skin surface
Blood’s adherence to the skin surface and sliding
even underneath a lower-horizontal surface can beexplained as a sort of physisorption due to van der
Waals force. Clavet et al. 2005 [1] added an attraction
force term formulated by a quadratic function for eachparticle to have antigravity nature, whereas theformulation appears to lack the physical basis, and thus
cannot express the adherence of blood to the skin very
well. Since van der Waals force is inversely proportional
to the seventh power of the distance between the objects,
we re-formulated the adsorption force by:f i adsorb = − ρkn,
(d i − d adsorb ) 7(1)where ρ denotes the particle density, di the distance
between particle i and the skin surface, and n the surface
normal. If di is smaller than d adsorb, the force becomesan infinity.
Adding the adsorption force in Eq. (1), a relatively
strong force acts onto the skin surface. If we still rely on
the traditional SPH collision process, which updates theparticle velocity only with the drag and friction
coefficients, the particles would be flown in unintended
directions. Therefore, after detecting the particle'spenetration into the skin surface, the position of thecolliding particle is projected feasibly onto the surface
with its velocity set to 0.
However, it may terminate the blood flow, because
each particle tends to continue staying at the same place.
To address the problem, we also considered thesaturation of adsorption sites, where if there are morethan a certain number of adhered particles, remaining
particles are forced to slip through, as shown in Fig. 3.

every second from each of the wounds. What can beobserved from the image sequence is the complicatedmerge and split patterns and dynamics of blood streaks
reflecting the face and wounds’ geometry. The
simulation ran at a rate of 7.4 FPS to yield the result
shown in middle snapshot on the above-mentioned PC.
For more details, consult the latest paper [3].

Fig. 3 Handling the case withsaturation of adsorption.
3. Implementation and Results
We defined the blood surface using the zero level set
method in a similar way as in Adams et al. 2005 [2].
The fluid surface mesh was extracted using an
accelerated Marching Cubes algorithm, and renderedwith an open-source ray-tracer named POV-Ray ver.
3.62. All the simulations and visualizations were carriedout on a standard PC (Intel Xeon E5540 2.53GHz CPU,
12GB RAM, and Quadro FX 4800 GPU). In the current
codes, the in-vivo simulation and surface reconstruction
phases have been parallelized on the GPU.
Fig. 4 contains three independent sequences ofresulting images, in order to prove how faithfully ourcodes can reproduce bleeding scenes. Fig. 4(a)delineates the bleeding from a wound on the forehead
getting adhered and sliding even underneath a lowerhorizontal surface due to physisorption. Fig. 4(b)visualizes the congelation effect through pseudo color
coloring, which changes normal blood’s color totranslucent red and scab’s color to opaque blue. In Fig.
4(c), we assumed that the volume per particle is 6 μℓ,
and about 2.0 mℓ blood (300 particles) was generated

4. Concluding Notes
In this initial report on the project, we have proposeda particle-based approach to visual simulation ofbleeding on skin surface. Although our current
simulation design policy is to trade physical accuracy
for visual reality and to be suited for the use in theaugmented reality environment, more physiologicallyprecise settings of hemorrhage volume and congelation
speed would extend the proposed scheme so as to be
applied to practical visual analysis for forensic purposes.
References
[1]

[2]

[3]

S. Clavet, P. Beaudoin, and P. Poulin: “Particle-based
Viscoelastic Fluid Simulation,” in Proceedings of the2005 ACM SIGGRAPH/Eurographics Symposium on
Computer Animation, pp. 219–228, 2005.
B. Adams, M. Pauly, R. Keiser, and L. J. Guibas:“AdaptivelySampled
ParticleFluids,”
ACM
Transactions on Graphics, Vol. 26, No. 3, Article 48,2007.
K. Ueda and I. Fujishiro: “Visual Simulation of Bleedingon Skin Surfaces Taking Physisorption and Congelation
into Primary Account,” in Proceedings of CG
International 2012, 2012.

(a) Physisorption effect.

(b) Congelation of bleeding from a simple wound.

(c) Complex pattern of bleeding from three wounds.
Fig. 4 Simulation results.