Mocap class 8 - Creating an interactive 3D garden JMG Spring 2011

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1 Mocap class 8 - Creating an interactive 3D garden JMG Spring 2011 INTRODUCTION: The interactive 3D garden project is a first step for creating a dynamic ecosystem, a natural environment where several animations happen simultaneously and are connected together. For example someone walking in the grass, clouds and wind blowing, flowers growing, insects and flock of birds crossing the sky. The interactive 3D garden is developed as a mini project that can easily grow into a substantial installation for your final project. The 3D garden project is an ideal theme for collaboration for a group of students. Although the dynamic events taking place in the garden are interconnected, they can be broken down into tasks. Designing interactions with motion capture, refining the viewer's experience, simulating growth and organic behaviors. Others can create original designs and plants by mixing 3D brushes in PaintEffects and animate, playing with the endless interactive transformations of attributes for shapes, colors, positions, scale, particles, light and cameras. Footsteps in the grass. On the left side, motion capture of foot steps in Kinect Open NI. On the right side, interactive animation of grass created with PaintEffects in Maya This presentation is an example of iterative process where the end of the process, animating and rendering the content is determinant in order to start creating the 3D content. For example, too much details can destroy tthe fluidity of the animation which is very important for the look and feel of the 3D garden. After experimenting with PaintEffect,

2 my last step was to create a friendly interactive interface to control specfic attributes inside the garden and to connect the interface with ranges of motion coming from the motion capture system. My presentation actually starts with the creation of the interactive interface which was the last step of my process. This case study was created by following the Edison method. It started with a catalogue of animations for grasss, flowers, tress and other tubes and meshes in PaintEffects. The most interesting modifiers and effects were kept after a systematic evaluation This means that I kepst the plants that were visually interesting for the graden and that could be animated during a live performance. Part 1- Building a 3D interface in Maya and connecting the interface to the motion capture system In Maya, build a central interface that can manage several animations coming from the motion capture system. We use DRIVEN KEYS applied to a simple sphere called for example Control sphere that will filter the range of motions and apply a specific transformation (move, rotate, scale) to a 3D arrow that will follow a specific movement. Let's build an interface with one degree of freedom Y AXIS using DRIVEN KEYS 3D Sphere DRIVER ATTRIBUTE SENDER drives CONTROLS sends values to 3D arrow DRIVEN ATTRIBUTE RECEIVER The viewer controls the animation of the high grass with footsteps moving from right to left, and bending with the wind. The growth of the flowers is controlled by motions of the hands.

3 YOU CAN SKIP THIS STEP by reusing the file DrivenKeys.fbx that contains a ready made interactive interface. The file is provided in the mocap-8 folder. HOW TO CREATE DRIVEN KEYS Let's link attributes for the Control Sphere and the 3D arrow Step 1- Go to Animation > Animate > Set Driven Key > Set. The Set Driver Key window opens up. Step 2- Select the Control Sphere, in the 3d Layout or in Outliner. In the Set Driver Key window, click Load Driver The Control Sphere appears in the Driver list. Click translate Y in the Driver list. The Control Sphere will send values for this attribute. Step 3- Select the 3D arrow in the 3D viewer or in Outliner. Load Driven for the 3D arrow as the Driven object. Click translate Y or another attribute in the Driven list. The 3D arrow will move according to values received fort this attribute. Step 4- Press the Key button The driven objetc changes color and becomes purple. Step 5- Move the Control sphere to a new position on the Y axis and move the 3D arrow to a new position on the Y axis. Press the Key button and create a second driven key Step 6- Go to Window > Animation > Graph Editor. Select the 3D arrow. Press A in the Graph Editor layout in order to center on the curve for the 3d arrow';s curve The Graph Editor shows the driven keys for the 3D arrow. MMB and edit the control points of the curve. This will change the motion of the 3D arrow. You can copu paste keys in the Garph editor, Go to Window > Animation > Graph Editor. IMPORTANT NOTE: This example shows a step-by-step for the translate Y attribute you can use any attriibute found in the Channel Box or in the Attribute Editor. More more in depth review of Driven keys check this excellent resource

4 ng_key.doc5.html CONNECTING THE INTERACTIVE INTERFACE TO KINECT USING POINT CONSTRAINTS IMPORTANT NOTE: The Control sphere is moved by Kinect, a motion capture system using POINT CONSTRAINT The control sphere uses Point Constraint to mimic the motion of a Null object from Kinect Open NI. Step 1- Select Animation, first select the Null object, second press CTRL + select the Control Sphere (Use the COMMAND key on a Mac) Create Point Constraint by selecting first a Null Object from Kinect Open NI and second the Control Sphere

5 Step 2- Go to Constrain > Point > Select Maintain Offset. This prevents the sphere from snaping on the Null object. The Null object will keep a constant distance from the sphere during the motion. BUILDING AN INTERFACE WITH 3 DEGREES OF FREEDOM X Y and Z We will repat what we did earlier for the X and Z axis After testing that the interface is working fine after adding the other driven keys. We have now three degrees of freedom.

6 Part 2- Using a pressure curve Let's test the interactive animation of a flower PaintEffect using a pressure curve TO CREATE A PRESSURE CURVE: Select a brush in the 3D viewer. Step 1- Go to Rendreing > PaintEffects > Curve Utility > Make Pressure Curve

7 Step 2- With the Pressure Curve selected, RMB on the curve > select Control Vertex. The number of vertices on the curve Distance of the curve from the brush Select control vertices and apply the Move tool in order to test the curve with a vertical tranlation. The plant will react to the motion of the curve Step 3- With the vertices selected, go to Animation > Create Deformers > Clusters Pressure curves work with control vertices which are a diffrent class of objects than 3D objects. You will need to use an ANIMATION CLUSTER in order to animate on one or several control vertices because 3D objects can be parented to CLUSTERS, not to Control vertices.

8 Testing with flowers Paint Effects

9 PART 3- Using one or two Control Stroke Curves Let's create an INTERACTIVE ANIMATION USING STROKE CONTROL CURVES Step 1- create a brush in Paint Effects. In order to react well to the curve, the tubes inside the brush need to have a minimum of 6 segments. To add segments to a brush-tube, go to the brush in Attribute Editor, select Mesh Tube Sections Scale of the brush Adds fluidity of deformation BUT this also increases the polygons count and slows down the animation

10 Step 2- Go to a side view. Select Create > CV Curve Tool > Draw a curve on the side of the brush. Step 3- SHIFT select first the curve and second the brush. Go to Rendering > PaintEffects > Curve Utilities > Set Stroke Control Curves Before and After Step 4- Go to the perspective view, deselect the brush and move the curve

11 You can edit the attraction of the Curve on the brush. Select the brush > Go to the Attrbute Editor Tubes > Behavior > Forces > Curve Follow and Curve Attract. You can limit the attraction of the curve past a certain disttance using Curve Max Distance.

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13 Testing an interactive animation using two STROKE CONTROL CURVES and a PRESSURE CURVE Part 4- Mixing brushes Since the 3D brushes in PaintEffects are generated from a same node, you can mix them together and create original designs. Without using scripting, you can blend Shades and Shapes. Step 1- Go to Rendering > PaintEffects > Get Brushes. (You can also Go to Windows > General Editors > Visor), Select a 3D brush, paint one element, for example a flower, or a limited amount of the brush, for example a patch of grass, in the 3D Layout. Step 2- Go to Rendering > PaintEffects > Preset Blending, click on the box on the left for the blending settings Step 3- Set values Shading and Shape in the Brush Preset Blend window Step 4- Select the second brush in Visor. Paint with the second brush in the 3D layout. The second brush becomes a new hybrid blending Shading and Shapes attributes You can save your new brush and add it to the Visor. BLENDING SHADES 50% blending between red and yellow flowers First Brush Second Brush without blending Second Brush with blending 0% Shape 41% Shading First Brush Second Brush without blending Second Brush with blending 0% Shape 72% Shading

14 BLENDING SHAPES blending a Vine with a Tulip Blending a Cactus with a Hamburger New brush Blending a Manhattan building with the branch of a tree A new 3D brush is created by blending 78% Shades 29% Shapes