CS 445 / 645 Introduction to Computer GraphicsPaul DebevecRendering with Natural LightFiat LuxLight StageMoving the Camera or the World?A 3D SceneViewing Transformations2 Basic StepsSlide 10Creating Camera Coordinate SpaceConstructing Viewing Transformation, VSlide 13Slide 14Composing Matrices to Form VSlide 16Slide 17Slide 18Final Viewing Transformation, VCanonical View VolumeWhy do we care?Projection NormalizationSlide 23Projection Normalization - OrthoSlide 25Projection Normalization - PerspPerspective NormalizationSlide 28Slide 29Slide 30Slide 31ColorBasics Of ColorBasics of ColorPhysiology of VisionSlide 36Physiology of Vision: ConesPhysiology of Vision: The RetinaPerception: MetamersPerception: Other GotchasPerception: Relative IntensityRepresenting IntensitiesSlide 43Dynamic RangesGamma CorrectionSlide 46CS 445 / 645Introduction to Computer GraphicsLecture 12Lecture 12Camera ModelsCamera ModelsLecture 12Lecture 12Camera ModelsCamera ModelsPaul DebevecTop Gun SpeakerTop Gun SpeakerWednesday, October 9Wednesday, October 9thth at 3:30 – OLS 011 at 3:30 – OLS 011http://www.debevec.orghttp://www.debevec.orgMIT Technolgy Review’s “100 Young MIT Technolgy Review’s “100 Young Innovators”Innovators”Top Gun SpeakerTop Gun SpeakerWednesday, October 9Wednesday, October 9thth at 3:30 – OLS 011 at 3:30 – OLS 011http://www.debevec.orghttp://www.debevec.orgMIT Technolgy Review’s “100 Young MIT Technolgy Review’s “100 Young Innovators”Innovators”Rendering with Natural LightFiat LuxLight StageMoving the Camera or the World?Two equivalent operationsTwo equivalent operations•Initial OpenGL camera position is at origin, looking along -ZInitial OpenGL camera position is at origin, looking along -Z•Now create a unit square parallel to camera at z = -10Now create a unit square parallel to camera at z = -10•If we put a z-translation matrix of 3 on stack, what happens? If we put a z-translation matrix of 3 on stack, what happens? –Camera moves to z = -3Camera moves to z = -3Note OpenGL models viewing in left-hand coordinatesNote OpenGL models viewing in left-hand coordinates–Camera stays put, but square moves to -7Camera stays put, but square moves to -7•Image at camera is the same with bothImage at camera is the same with bothTwo equivalent operationsTwo equivalent operations•Initial OpenGL camera position is at origin, looking along -ZInitial OpenGL camera position is at origin, looking along -Z•Now create a unit square parallel to camera at z = -10Now create a unit square parallel to camera at z = -10•If we put a z-translation matrix of 3 on stack, what happens? If we put a z-translation matrix of 3 on stack, what happens? –Camera moves to z = -3Camera moves to z = -3Note OpenGL models viewing in left-hand coordinatesNote OpenGL models viewing in left-hand coordinates–Camera stays put, but square moves to -7Camera stays put, but square moves to -7•Image at camera is the same with bothImage at camera is the same with bothA 3D SceneNotice the presence ofNotice the presence ofthe camera, thethe camera, theprojection plane, and projection plane, and the worldthe worldcoordinate axescoordinate axesViewing transformations define how to acquire the image Viewing transformations define how to acquire the image on the projection planeon the projection planeNotice the presence ofNotice the presence ofthe camera, thethe camera, theprojection plane, and projection plane, and the worldthe worldcoordinate axescoordinate axesViewing transformations define how to acquire the image Viewing transformations define how to acquire the image on the projection planeon the projection planeViewing TransformationsGoal: To create a camera-centered viewGoal: To create a camera-centered viewCamera is at originCamera is at originCamera is looking along negative z-axisCamera is looking along negative z-axisCamera’s ‘up’ is aligned with y-axis Camera’s ‘up’ is aligned with y-axis (what does this mean?)(what does this mean?)Goal: To create a camera-centered viewGoal: To create a camera-centered viewCamera is at originCamera is at originCamera is looking along negative z-axisCamera is looking along negative z-axisCamera’s ‘up’ is aligned with y-axis Camera’s ‘up’ is aligned with y-axis (what does this mean?)(what does this mean?)2 Basic StepsStep 1: Align the world’s coordinate frame with Step 1: Align the world’s coordinate frame with camera’s by rotationcamera’s by rotationStep 1: Align the world’s coordinate frame with Step 1: Align the world’s coordinate frame with camera’s by rotationcamera’s by rotation2 Basic StepsStep 2: Translate to align world and camera Step 2: Translate to align world and camera originsoriginsStep 2: Translate to align world and camera Step 2: Translate to align world and camera originsoriginsCreating Camera Coordinate SpaceSpecify a point where the camera is located in world Specify a point where the camera is located in world space, the space, the eye point (View Reference Point = VRP)eye point (View Reference Point = VRP)Specify a point in world space that we wish to become Specify a point in world space that we wish to become the center of view, the the center of view, the lookatlookat point pointSpecify a vector in worldSpecify a vector in worldspace that we wish to space that we wish to point up in camera point up in camera image, the image, the up vector (VUP)up vector (VUP)Intuitive camera Intuitive camera movementmovementSpecify a point where the camera is located in world Specify a point where the camera is located in world space, the space, the eye point (View Reference Point = VRP)eye point (View Reference Point = VRP)Specify a point in world space that we wish to become Specify a point in world space that we wish to become the center of view, the the center of view, the lookatlookat point pointSpecify a vector in worldSpecify a vector in worldspace that we wish to space that we wish to point up in camera point up in camera image, the image, the up vector (VUP)up vector (VUP)Intuitive camera Intuitive camera movementmovementConstructing Viewing Transformation, VCreate a vector from eye-point to lookat-pointCreate a vector from eye-point to lookat-pointNormalize the vectorNormalize the vectorDesired rotation matrix should map this vector Desired rotation matrix should map this vector to [0, 0, -1]to [0, 0, -1]T T Why?Why?Create a vector from eye-point to lookat-pointCreate a vector
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