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Published byLeon Greene Modified over 9 years ago
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Imaging
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Modeling and Imaging Reality model Picture modeling Imaging (vizualisation)
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Projection Mapping Φ: R n → R k n>k In case of 3D computer graphics Φ: R 3 → R 2 Projection ray –The set of all pictures with the same image –Projection ray is usually a line –The image is in the intersection of the projection ray and the projection plane.
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Parallel projection Intersection of projection rays (projection center) is in the infinity Projection rays are parallel Their direction is defined by two angels (azimuth,zenith)
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Axonometry Projection plane intersects coordinate axes dy dx dz
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Dimetry Projection triangle is isiscelles
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Izometry Projection triangle is equilateral (dx=dy=dz) Often also azimuth=zenith=45 o
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Perspective Projection center is a point
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1-vanishing point perpective
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2-vanishing point perspective
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3-vanishing point perspective
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Wireframe „model“
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Solving of edges visibility
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Which faces are visible? The normal leads TO the observer → the face can (but must not) be visible The normal leads from the observer → the face is not visible
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Painter’s algorithm Display the potentionaly visible faces from the back to the front
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Painter’s algorithm The face is not visible
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Painter’s algorithm The face can be visible
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Painter’s algorithm The face is not visible
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Painter’s algorithm The face can be visible
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Painter’s algorithm The face is not visible
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Painter’s algorithm The face can be visible
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Painter’s algorithm The face is not visible
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Painter’s algorithm The face is not visible
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Painter’s algorithm The face can be visible
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Painter’s algorithm The face can be visible
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Counter example of painter’s algorithm
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Simple imaging of all points of the solid
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Rendering Light source observer Projection plane Angle α
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Rendering
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Light source types Point Point with directed lights (commonly cone shape) Area (commonly approximated by a matrix of points) Ambient
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Ray Tracing Light sources Projection plane Mirror reflection Diffuse reflection The ray goes through the solid
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Types of reflection on the solid The ray is absorbed by a solid (solid color) The ray is reflected –Mirror reflection (shine) –Diffuse reflection –Combinated reflection The ray is going through the solid tělesem –Directly (transparent solid) –With a shift –With a diffusion (translucent solid)
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Ray Tracing
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Radiosity E i = z i + o i * ∑v ij e j
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