 ICACT20220105 Slide.01
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Artical: A technique to improve the displaying quality of skin deformation caused by external force.
Authors: Nguyen Duc Hoang, Do Nang Toan, Nguyen Tuan Minh |
| ICACT20220105 Slide.02
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This article continues the research on simulation of preclinical medical practice started by Do Nang Toan and Nguyen Duc Hoang. In previous research, a technique to present colour of the human skin was introduced and in this rearch we continue improve the displaying quality of skin deformation cause by external force. Pressing on the skin and observing changes in capillary refill time (CRT) of human skin to evaluate the patient’s health though terms of blood pressure, heart rate, etc. is an indispensable operation in medical examination and treatment. This articale mentions a technique to improve the detail of the deformation of the shape of human skin affected by external force without increasing the detail of the entire object. The proposed technique is applied on a 3D model simulating emergency medical practice of children in Vietnam and proved to be effective in displaying the deformation of the shape of human skin caused by the external force
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| ICACT20220105 Slide.03
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Introduction: An area of skin under an external force such as a pressing action, in addition to the color being changed due to the amount of blood in the capillaries in the affected area being pushed out, its shape is also stretched belong to the direction of the external force
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| ICACT20220105 Slide.04
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In the previous research, we proposed a skin simulation technique that improved the skin color rendering under external force. The change in skin color under the influence of external force is more accurate based on the change in the coating but does not improve the detail of the subject and it also making the affected skin area streiched uneven
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| ICACT20220105 Slide.05
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In this paper, we present a technique to simulate the change in shape of human skin under the influence of external force by increasing the extensibility of the skin affected by the pressure without increasing the detail of the whole skin. object. The rest of the paper is presented as follows: Section 2 presents the theoretical basis of the research. Part 3 is the proposed simulation algorithm. This is followed by testing and finally conclusions on the proposed technique |
| ICACT20220105 Slide.06
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Background Knowledge: The background knowledge we present in this paper include the algorithm to calculate the deformation of the object shell that has been meshed in quadrangle in the process of manual shaping and the algorithm to automatically generate the mesh into a triangle from the given vertices on the object surface
To simulate the deformation of the skin layer under external force, we consider the skin layer as a shell that is homogene in composition, so the hardness of the skin layer is also considered to be homogene
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| ICACT20220105 Slide.07
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The theory in determining the deformation of the solid object has been researched in the machine industries, in subsequent research, this theory is also applied to 3D object simulation: Mindlin and Reissner |
| ICACT20220105 Slide.08
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Mindlin theory for plates is calculated in finite elements of plates. The equation in slide describes it. |
| ICACT20220105 Slide.09
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The simulation technique:
Technical analysis
To increase the detail of the deformed area, you can use the method: increase the number of meshes of the 3D object but it increases the weight of the simulation program
The proposed technique aims to increase the display quality for objects in virtual space subject to shape changes by forces acting on the surface: increase the number of instantaneous grids in the affected area
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| ICACT20220105 Slide.10
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Technical analysis
The main problems: determining the point of application of the force and the main impact zone on the object surface, determining the deformation on the main impact area and showing it
Solution:
At the point of impact, find the nearest nodal point and apply the force on it with the same direction and direction as the applied force.
At the point of impact, delineate the main affected area (the largest deformation occurs in this area) then automatic mesh generation by earcliping algorithm
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| ICACT20220105 Slide.11
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Description of technical details
Input: The surface of the affected object is designed in the form of a quadrangle grid. The algorithm is installed on the vertex system of the quadrangle meshes on the model. The impact force is generated by placing a force vector at a point on the object surface.
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| ICACT20220105 Slide.12
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Methods of implementation :
Step 1: From the point of placing the force on the mesh, find the nearest node and apply the force on that node
Step 2: Determine the area affected by the force on the grid system and increase the number of nodes.
Step 3: Find the displacement matrix of neighboring nodes under the action of the force according to the finite element method
Step 4: Build a new grid system on a new system of nodes using Earclipping technique
Step 5: Render the shape of the object based on the newly built mesh system
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| ICACT20220105 Slide.13
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Two images describe the results of our technique. Picture above is Deformed child skin object surface under force using finite element algorithm without mesh generation and picture below is Deformed object surface under force using finite element algorithm with k = 4 |
| ICACT20220105 Slide.14
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Out put: The output of the algorithm is a new mesh system of deformed objects under the impact of external forces. This mesh system can be retained after the skin is subjected to force, but our recommendation is to restore the subject's old mesh system to reduce the load on the system |
| ICACT20220105 Slide.15
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The simulation is performed on a 3D model of a 1-year-old child's body with the number of meshes: 64,004 (tris); Reference height: 80cm; head length: 20cm; Sleeve length: 63cm
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| ICACT20220105 Slide.16
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It is easy to compare the simulated surface using the new technique is more detailed distortion than the original surface:
When the new technique is not applied, the surface is decomposed into very clear arrays according to the mesh edges, when using the proposed technique, the deformation is expressed as a set of straight lines gradually asymptotically becoming a curve from picture a to b to c
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| ICACT20220105 Slide.17
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Conclution: Simulating emergency medical practice with children in Vietnam is an important issue for research on digital transformation applications in the medical industry. In particular, the manipulation of pressing on the skin and observing changes in the time of subcutaneous capillary filling (CRT) to assess the patient's health in terms of blood pressure, heart rate, etc., is an indispensable operation in medical examination and treatment. . The article proposes a technique to increase the detail of the shape change of the skin under pressure by using the theory of deformation of Mindlin and Reissner plates combined with the finite element method to determine Specifies the transformation of the nodes on the 3D object surface mesh.
The proposed technique is applied on a 3D model simulating emergency medical practice with children in Vietnam and proved to be effective in displaying the change in the shape of the skin when subjected to external forces
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| ICACT20220105 Slide.18
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This is our references articals. Our previous research is the reference number 01. |
| ICACT20220105 Slide.19
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And this is our team's bio |
| ICACT20220105 Slide.20
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Thanks for watching! |
