IMAGE SYNTHESIS 1

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 2

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 3

Computed Tomography Uses digital computation techniques 2D synthetic cross-sectional image is made of 1D projections CT is vital for medicine 4

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 5

Examples MRI image, human skull Cross-sectional CT image of human brains 6

Examples 2 Cross-sectional images from thorax 7

Projections 8

2D Images From Projections (object: a ball) 9

Details of CT scanning ciples_of_ct/img0.html ciples_of_ct/img0.html 10

MRI = Magnetic Resonance Imaging 11 3D image from 2D´s

Videos on MRI Physics of MRI Patient training for MRI-imaging Patient training for MRI-imaging 12

3D Scene Construction From Images Stereo image pairing 13

Depth Perception Based on: two eyes, stereo vision (or stereoscopy) relative object sizes object shading and shadowing object obscuring atmospheric haze 14

Stereoscopy 15

Stereo Image Pair Two images of the same scene with different view angles 16

Image Cross-Section Stacking CT and MRI Sequential material removal Confocal laser scanning microscope (material must be transparent) 17

Image Cross-Section Stacking Image is shown stacked or sequential 18

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: 19

Example on a voxel image 20

Voxels in videos Brain MRI 3D Aorta CT Kinect User Interface Brain AVM 3D MRI 21

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Visualization of Non-image Data CAD rendering (computer aided design) Elevation data rendering 3D scanning Visualization of abstract data 23

CAD Rendering 24

CAD Rendering Methods Wireframe model Hidden-line removal Solid model Tinted solid model 25

3D Rendering In 3D rendering following methods are used: A model is created from sample points A real object is a model A brand new object is created 26

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 27

Methods In wireframe polygons can be seen as borderlines In hidden-line removal lines behind the polygons are not drawn 28

Methods Solid model rendering Surface and color 29

Methods Shaded solid model A surface can also illustrate different materials such as metal or plastic 30

Texture and lighting Images we create can look like real when we add different surfaces on them and illuminate them with multiple light sources 31

Photo-realistic Rendering Materials, light refraction and reflections 32

33 Elevation data rendering

Elevation Model - Reflection planes 34

The Calculation of A Reflectance 35

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Example of Digital Terrain Model 38

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3D-lightingModels 40

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 41

The Use of 3D Models In industry 3D rendering before building an expensive prototype 42

The Use of 3D Models Commercial use and entertainment industry Games, movies and TV-programs 43

3D Examples The features of the light can be rendered well, but this requires substantial computing power 44

3D Examples The 3D- models have almost totally replaced the plastic models in the movie industry 45

The future of the 3D-graphics Virtual reality? 46

Examples of 3D animation Birth 3DDentalPlanning Fertilization 47