Transcript Kuva-analyysi

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IMAGE SYNTHESIS
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Image Synthesis
• Image synthesis operations create images from other
images or non-image data
• Used when a desired image is either physically
impossible or impractical to acquire
• CT-image, CAD, abstract data, image composition, 3D
graphics
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Tomography
• Creates cross-sectional images of solid 3D
objects
• Based on X-ray imaging
• The technique is implemented by moving an
X-radiation source and an x-ray detector in
parallel and opposing directions, pivoting
about the plane of interest
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Computed Tomography
• Uses digital computation techniques
• 2D synthetic cross-sectional image is made of 1D
projections
• CT is vital for medicine
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Computed Tomography
• Transmissive mode
• Computed Tomography
• Based on X-radiation
• Emissive mode
• MRI (Magnetic Resonance Imaging)
• PET( Positron Emission Tomography)
• Reflective mode
• radar imaging, ultrasonic
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Projections
2D Images From Projections
(object: a ball)
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Details of CT scanning
8b Computed_Tomography_I.ppt
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MRI = Magnetic Resonance Imaging
3D image from 2D´s
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Videos on MRI
Physics of MRI
• Patient training for
MRI-imaging
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3D Scene Construction From Images
• Stereo image pairing
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Depth Perception
• Based on:
• two eyes, stereo vision (or stereoscopy)
• relative object sizes
• object shading and shadowing
• object obscuring
• atmospheric haze
Stereoscopy
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Stereo Image Pair
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• Two images of the same scene with different
view angles
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Volume Rendering Slice-Image
• Slice-image is two-dimensional and has no depth
• Convert 2Ds (x,y) into 3D (x,y,z)
• z is a cross-sectional surface index
• z is usually coarser than x,y. Intermediate slices are
created by interpolation methods
• Voxel can represent multiple features such as
brightness, color and transparency
• See: http://en.wikipedia.org/wiki/Voxel
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Example on a voxel image
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Voxels in videos
• Brain MRI
• Kinect User Interface
• 3D Aorta CT
• Brain AVM 3D MRI
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Visualization of Non-image Data
• CAD rendering (computer aided design)
• Elevation data rendering
• 3D scanning
• Visualization of abstract data
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CAD Rendering
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CAD Rendering Methods
• Wireframe model
• Hidden-line removal
• Solid model
• Tinted solid model
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3D Rendering
In 3D rendering following methods are
used:
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A model is created from sample
points
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A real object is a model
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A brand new object is created
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3D Rendering
• 3D object model can be composed of surfaces,
polygons or of a combination of above
• Surfaces are utilised to render simple objects (balls,
sylinders)
• An arbitary plane can be rendered by using this kind of
polygons
Methods
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• In wireframe polygons can be seen as borderlines
• In hidden-line removal lines behind the polygons are
not drawn
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Methods
• Solid model rendering
• Surface and color
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Methods
• Shaded solid model
• A surface can also illustrate
different materials such as
metal or plastic
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Texture and lighting
• Images we create can look like real when we
add different surfaces on them and illuminate
them with multiple light sources
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Photo-realistic Rendering
• Materials, light refraction and
reflections
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Elevation data rendering
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Elevation Model Reflection
planes
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The Calculation of A Reflectance
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Example of Digital Terrain Model
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3D-lightingModels
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The Use of 3D Models
• In scientific research 3D models are used to render
objects which are too small, large, fast or slow to be
viewed by other ways
• Examples:
• atoms,
• molecules,
• Explosions
• etc
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The Use of 3D Models
• In industry 3D rendering before building an expensive
prototype
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The Use of 3D Models
• Commercial use and entertainment
industry
• Games, movies and TV-programs
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3D Examples
• The features of the light
can be rendered well, but
this requires substantial
computing power
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3D Examples
• The 3D- models
have almost totally
replaced the plastic
models in the movie
industry
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Examples of 3D animation
• Birth
• 3DDentalPlanning
• Fertilization