CGS 3034 – Lecture 3Car Crash

Introduction to Computer Aided Animation

Instructor: Brent Rossen

Overview

Virtual Dub for RenderingObject vs. World Coordinate SystemsCenter PivotTire Problem - Rotate in 2 axis problemTire Problem Solution - Animation HierarchyToy Car Modeling - Hierarchy OrganizationToy Car AnimationCamera and AimCamera AnimationRendering Differences – Toy Car Animations

Toy Car – Fast Rendering (15 Min)

Depth Map Shadows Only

Virtual Dub

http://www.virtualdub.org/Open Source, Fast, and SimpleRender your animation to .bmpOpen the animation (images folder) with virtual dubChange Video > Compression… to XVidSave As AVI…

Object vs. World

Object Coordinates: the coordinate system according to the objectWorld Coordinates: the coordinate system according to the world

Centering The Pivot Point

Modify > Center Pivot Symmetrical Objects Only

Hit Insert to modify pivot point by hand

Un-centered vs. Centered

Tire Problem – The Wobbles

Try ThisCreate > Nurbs Primitive > Torus Options

Orient Towards Z Axis, CreateKeyframe: Time-Value-Key

Frame:1 - Rotate Z:0 - KeyFrame:24 - Rotate Z:720 - KeyFrame:1 – Translate X,Y:0,0 – KeyFrame:24 – Translate X,Y: 5,5 – KeyRotate Y:45

What’s wrong? It does the wobble-spin and it makes the animator cry.

Tire Problem – Wobble

Tire Problem – Wobble vs. Spin

Tire Problem – Solution: Animation Hierarchies

Edit > Group your wheel twiceWindow > Outliner

Let’s you view your group hierarchyShift-click the + to open the whole hierarchy

Rename your original wheel, “wheelSpinZ”Rename the group above the wheel, “wheelRotateY”Rename the group above “wheelRotateY” to “wheelTranslateXZ”

Tire Problem Solution – Reanimate

Window > Animation Editors > Graph EditorExcept the Z rotations, get rid of all the keyframes on wheelSpinZ from before the grouping Select wheelRotateY, go to the Attribute Editor, rotate Y: 45 degreesSelect wheelTranslateXZ:

Frame:1 – Translate X,Z: 0,0 – Key XZFrame:24 – Translate X,Z: 5,5 – Key XZ

Rejoice! Now it animates properly.

Good Wheel Rotation

Gimbal Lock

Gimbal Lock: When one rotational axis is placed on top of anotherThis would make 2 axes lead to the same result when animatedAdd extra nodes then do each axis of rotation separately, this avoids Gimbal Lock

Toy Car

Car HierarchyCabBodyFront Axel

Front TiresRear Axel

Rear Tires

Toy Car – Create Cab

CabCreate > Polygon Primitive > Cube optionsSubdivisions along width, height, and depth = 3F8 to component mode, deform as appropriatePolygons > SmoothSimilar for body

Note: 4 subdivisions along widthNURBS Torus for WheelsNURBS Cylinder for Axels

Toy Car – Cab

Toy Car – Cab & Body

Toy Car – Smooth

Toy Car – Grouping

Car HierarchyGroup Front Tires with Front AxelGroup Rear Tires with Rear AxelSelect Cab, Body, “frontTireGroup”, and “rearTireGroup”

Group them all together rename “ToyCar”Children move with the parent, but not the other way around

Group: CTRL – g OR Edit > Group

Toy Car – Animation Notes

Window > OutlinerSelect “ToyCar” groupSet all car movements on group “ToyCar”Set wheel rotation on each tireGroupseparately

Be sure the pivot points are centered on these groups

Adjust animation curves in Graph Editor for each group

Camera Animation

Camera TypesCamera – difficult to controlCamera and Aim – Just rightCamera, Aim, and Up – can cause motion sickness

Create > Cameras > Camera and AimHotkey t (Show Manipulator Tool) will let you change the Camera Node and Aim Node Separately

Camera Animation - Snapping

Snap Aim to ObjectSelect Car Body – Make Live ButtonOR Modify > Make Live

Select Camera – Press tMove Aim Node – it will snap to car body

Move aim node and keyframe translation attributes at each frame you want the camera centered on the objectRemove Make Live from Car Body

Camera Animation – Live Body

Camera Animation – Target Grouping

The other option is to make the “ToyCar”object the parent of the TargetThat way all translations applied to the “ToyCar” group will also be applied to the targetCreates perfect tracking, which you might not want for camera realism

Rendering – Normal, Blur, Raytracing

If your render time is too large, take out blur and raytracing, they aren’t that critical for these first projectsExamples to follow:

Rendering – Basic, Blur, Raytrace

Toy Car – Fast Rendering (15 Min)

Depth Map Shadows Only

Toy Car – Long Rendering (1 Hour)

Includes Ray Trace and Motion Blur