A1262287558sQdbP

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???????????????????????? Ian Thomas
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Rendering and 3D models
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???????????????????????? Ian Thomas
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Shading
Flat
Gouraud
Phong
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???????????????????????? Ian Thomas
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Shading
Simple shading model The surface absorbs light
and re-emits light in all directions according to
Lamberts law.
normal
q
IL is the incident light intensity KD is the
diffuse reflection coefficient
In practice use an ambient light term
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???????????????????????? Ian Thomas
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Renderer
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???????????????????????? Ian Thomas
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Gouraud shading model The intensity of each
facet is calculated, and interpolation used to
calculate the best intensity at a point.
normal
q2
q1
q3
http//www.siggraph.org/education/materials/HyperG
raph/scanline/shade_models/shadgou.htm
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???????????????????????? Ian Thomas
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Find the average normal at each vertex
Phong shading
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???????????????????????? Ian Thomas
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Surface models of muscles
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???????????????????????? Ian Thomas
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Extracting bone model from 3D dataset
9
???????????????????????? Ian Thomas
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Making three dimensional models of the human leg
at KKU.
10
???????????????????????? Ian Thomas
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A series of parallel slices was made through the
lower leg using MRI.
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???????????????????????? Ian Thomas
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Creating an array of points along with boundaries
of regions. The boundaries were entered manually,
while the points were computer generated.
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???????????????????????? Ian Thomas
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The slices were combined into an array of
parallel slices.
13
???????????????????????? Ian Thomas
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The Delauney method in 2 dimensions was applied
to create triangles from points in a slice.
The third point which makes a triangle with the
smallest circle through its points is chosen.
14
???????????????????????? Ian Thomas
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The Delauney method in three dimensions was used
to link triangles to points in other slices. The
fourth point which makes the smallest sphere
through the points of the tetrahedron is chosen.
4
1
3
2
15
???????????????????????? Ian Thomas
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Tissue NMR information is then added to the three
dimensional model. The NMR parameters are spin
density, T1 and T2 relaxation times.
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???????????????????????? Ian Thomas
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The model is complete and can be used to create
synthetic views and slices. An NMR sequence is
chosen to create the image. In this work the spin
echo sequence was used.
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???????????????????????? Ian Thomas
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The Karlsruhe surgery trainer from Germany