Open the chase_v01.ma scene from the chapter2/scenes folder on the DVD. You'll find that a simple animatic of a car racing down a track has been created.

Create a new camera (Create

Figure 2.3. A new camera is created and renamed in the Outliner.

In the Display Layer Editor, turn off the visibility of all the layers except street to hide the unnecessary geometry in the scene.

Display Layers

Display layers are found below the Channel Box on the right side of the screen. Clicking the V button toggles the visibility of the layer.

Select shotCam1 in the Outliner, and press the f hot key to focus on this camera in the viewport.

The icon for the camera looks like a movie camera. It has a transform node and a shape node. The camera attributes are located on the shape node.

Select shotCam1, and switch to the Move tool (hot key = w). Move the camera up from the center of the grid to the level of the street. Set the Translate X, Y, and Z channels to 1.382, 4.138, and −3.45.

In the toolbox, click the Show Manipulator tool (the bottom icon in the toolbox). If you zoom out in the viewport, you'll see the camera has a second positional icon; this is the center of interest (see Figure 2.4). The value shown in the camera's Channel Box for the center of interest is the distance (in the scene's working units—meters for this scene) between the camera and the center of interest. Grab this part of the manipulator and position it on the street so the camera is looking up the road (toward the beginning of the track where the car starts). This is one technique for aiming the camera.

In the Viewport panel menu, choose Panels

Figure 2.4. The Show Manipulator tool allows you to aim the camera using a second transform manipulator.

Maya 2009 has added icons to the Viewport panel so that you can quickly access common viewport settings (see Figure 2.5). The first group of icons on the left side is directly related to camera display options. Starting from the left, here is a list of the actions associated with each icon:

In the Display Layer Editor, turn on the buildings layer so the buildings are visible. Tumble around in the viewport (LMB-drag while holding down the Alt key) so you can see part of the large building to the left of the street.

In the panel view, turn on the Resolution Gate. Click the Camera Attributes icon to open the Attribute Editor for shotCam1.

The image size of this scene is set to 1280 × 72., which is the HD 72. preset. You can see the image resolution at the top of the screen when the Resolution Gate is activated. Working with the Resolution Gate on is extremely helpful when you're establishing the composition of your shots (Figure 2.6).

Figure 2.6. The Resolution Gate is a helpful tool when framing a shot.

When you create a new camera to render the scene, you need to add it to the list of renderable cameras in the Render settings. You can render the scene using more than one camera.

Scroll down in the Attribute Editor for shotCam1 and expand the Output Settings area. Make sure the Renderable option is selected.

Open the Render Settings window. In the Renderable Cameras area, you'll see both the shotCam1 and persp cameras listed (see Figure 2.7). To remove the perspective camera, click the trashcan to the right of the listing.

Figure 2.7. Cameras can be added to the list of renderable cameras in the Render Settings window.

Select shotCam1 and open its Attribute Editor to the shotCam1Shape tab. In the Controls drop-down list, you have the option of switching to a camera with an aim node or to a camera with an aim and an up control. Set the camera to Camera And Aim (Figure 2.9).

A single-node camera is just a plain camera like the perspective camera. You can change its rotation and translation by setting these channels in the Channel Box, using the Move and Rotate tools, or tumbling and tracking while looking through the camera.

Figure 2.9. You can add additional camera controls using the Controls menu in the Attribute Editor. The camera is then grouped in the Outliner with a separate aim control.

Moving the Camera

A camera can be translated and rotated using the standard transform tools. This is done when you are viewing the camera from another camera. When you are looking through a camera, you can use the same hot keys you use while moving around the perspective camera:

• Alt+LMB = Tumble, also known as rotating the camera.

• Alt+MMB = Track; this is the same as moving the camera on the X and Y axes.

• Alt+RMB = Dolly; this is the same as moving the camera on the Z axis, also known as pushing the camera.

Additional camera movement controls are found in the panel's View menu; just choose View

By default, each change in position that results from tumbling, tracking, or dollying a camera view is not undoable. You can change this default by activating the Undoable Movements option in the camera's Attribute Editor; however, this may add a lot to the Undo cue. Alternatively, you can use the bracket hot keys, [ and ], to move between previous views. Bookmarks are also a good way to store camera views. It's also common to set a keyframe on a camera's Translation and Rotation settings as a way of storing the position. The keyframe can be used as part of an animation or deleted if it's not needed in the final animation.

A two-node camera is a camera with a separate aim control grouped together. When you switch to this type of camera (or create this type of camera from the Create

A three-node camera is created when you choose Camera, Aim, And Up from the Controls menu. This adds a third locator, which is used to control the camera's rotation around the Z axis. These controls and alternative arrangements will be explored later in the section on camera rigs.

When working with two- or three-node cameras, resist the temptation to move or keyframe the position of the group node that contains both the camera and the aim locator. Instead, expand the group in the Outliner and keyframe the camera and aim nodes separately. This will keep the animation simple and help to avoid confusion when editing the animation. If you need to move the whole rig over a large distance, Shift+click both the camera and the aim locator, and move them together. Moving the group node separately is asking for trouble.

Expand the shotCam1_group node that now appears in the Outliner, and select the shotCam_aim node. In the Channel Box, set its Translate X, Y, and Z settings to −0.155, 4.2.6, −2.884. (The camera's node should still have its X, Y, and Z translation settings at 1.382, 4.138, and −3.45.)

In the Display Layer menu, turn on the car layer. Set the current frame to 60 so that the car is in view of the camera.

In the Attribute Editor for shotCam1, adjust the Angle Of View slider. Decreasing this setting flattens the perspective in the image and zooms in on the scene; increasing this setting exaggerates the perspective and zooms out.

With the camera still selected, switch to the Channel Box and find the Focal Length setting under the shotCamShape1 node. Highlight the Focal Length channel label, and MMB-drag back and forth in the viewport window. Set the Focal Length to 2. (see Figure 2.10).

Figure 2.10. The Angle Of View slider in the Attribute Editor and the focal length attribute in the Channel Box both adjust the zoom of the camera.

From the Panel menu choose Panels

Select shotCam1 and choose the Show Manipulators tool from the toolbox. Zoom in on the shot cam, and click the blue manipulator switch (located just below the camera when the Show Manipulators tool is active; see Figure 2.12) twice to switch to the clipping plane display.

Figure 2.12. Clicking the blue switch below the Show Manipulators tool cycles through the various actions of the tool. Clicking twice activates the manipulators for the clipping planes.

The clipping plane manipulator consists of two blue rectangles connected by lines. The near clipping plane is a small rectangle very close to the camera; the far clipping plane is very large and far from the camera

Zoom in close to the shot cam and MMB-drag the near clipping plane manipulator. You can set the position of this clipping plane interactively. Note that as you move the plane away from the camera, the geometry in the shotCam1 view is cut off. Any object between the camera and the near clipping plane will not render or will only partially render.

Zoom out until you can see the far clipping plane manipulator. MMB-drag on this and bring it in closer to the camera. Objects beyond this clipping plane will not be rendered by the camera or will appear cut off.

In the Attribute Editor for the shotCam1Shape node, set Near Clip Plane to .05 and Far Clip Plane to 85 (the units for this scene are set to meters). This is a good starting place; if the positions of the planes need to change later on, they can be adjusted (see Figure 2.13).

Save the scene as chase_v02.ma. To see a version of the scene to this point, open chase_v02.ma from the chapter2/scenes directory on the DVD.

Continue with the scene from the previous section or open the chase_v02.ma scene from the chapter2/scenes directory on the DVD. Set the current camera in the viewport to shotCam1 and the timeline to frame 61.

In the Display layers, turn on the choppers layer so that the helicopter is visible in the shot.

Open the Attribute Editor for shotCam1, and switch to the shape node (shotCam1Shape) tab. In the Film Back rollout, set the Film Offset to 0.2 and −.05. Notice how this change alters the composition of the frame. Even a small change can affect the emotional impact of a shot (see Figure 2.15).

Figure 2.15. Adjusting the Film Offset changes the framing of the shot without actually moving the camera or the perspective of the image.

Turn on the Shake Enabled option. Right-click the first field in the Shake option, and choose Create New Texture from the pop-up window (see Figure 2.16).

Switch to the Textures tab in the Create Render Node window, choose Fractal from the 2D Textures section, and make sure Normal is selected. The camera view will move when you add the texture, and that's okay.

Figure 2.16. Right-click the attribute field and choose Create New Texture. The Create Render Node window will open.

The attributes for the fractal texture will appear in the Attribute Editor. Set the Amplitude to 0.1.

Check the Animated check box to enable the animation of the texture. Rewind the animation. Right-click the Time attribute, and choose Set Key (see Figure 2.17).

Figure 2.17. To animate a fractal texture, turn on the Animated option and set keyframes on the time slider.

Set the Timeline to frame 2.0. Set the Time attribute to 100, and set another key. Rewind and play the animation; you'll see the camera move back and forth.

Repeat steps 1 though 5 for the Vertical setting in Shake to add another animated fractal texture to this attribute. You want to have a different texture for each setting so that horizontal and vertical shaking of the camera are not the same value; otherwise the camera will appear to shake diagonally.

Select the second fractal texture, expand its UV Coordinates rollout, and click the arrow to the right of it to go to the fractal texture's place2dTexture node. Set the Rotate UV value to 45. This rotates the texture so that the output of this animated texture is different from the other, ensuring a more random motion.

You may notice that the shaking is nice and strong but that you've lost the original composition of the frame. To bring it back to where it was, adjust the range of values created by each texture. The Fractal Amplitude of both textures is set to 0.1, which means each texture is adding a random value between 0 and 0.1 to the film offset. You need to equalize these values by adjusting the Alpha Offset and Alpha Gain of the textures.

Open the Hypershade by choosing Window

Hold the mouse over the line connecting one of the textures to the shotCamShape1 node. The pop-up label shows that the outAlpha attribute of the texture is connected to the vertical or horizontal shake of the camera. This means that the outAlpha value must be adjusted to compensate for the change made to the camera's offset (see Figure 2.18).

If you look at what's going on with the fractal texture, you'll see that when the Amplitude of the texture is set to 0, the outAlpha value is 0.5 (you can see this by switching to the shotCamShape1 tab and looking at the Horizontal Shake field). The fractal texture itself is a flat gray color (value = 0.5). As you increase the Amplitude, the variation in the texture is amplified. At an Amplitude of 1, the outAlpha ranges from 0 to 1. You can see this in the values generated for the Shake attribute in the camera node. This is a very large offset and causes the shaking of the camera to be very extreme. You can set the amplitude to a very low value, but this means that the outAlpha value generated will remain close to 0.5, so as the shake values are added to the film offset, the composition of the frame is changed—the view shifts up to the right.

To fix this, you can adjust the Alpha Gain and Alpha Offset attributes found in the Color Balance section of each fractal texture. Alpha Gain is a scaling factor. When Alpha Gain is set to 0.5, the outAlpha values are cut in half; when Alpha Gain is set to 0, the outAlpha is also 0, and thus the Shake values are set to 0 and the camera returns to its original position. So if you want to shake the camera but keep it near its original position, it seems as though the best method is to adjust the Alpha Gain of the fractal texture.

Figure 2.18. The outAlpha value generated by the animated fractal texture is connected to the camera's horizontal shake.

However, there is still one problem with this method. You want the outAlpha of the fractal to produce both negative and positive values so that the camera shakes around its original position in all directions. If you set the Alpha Gain to a positive or negative number, the values produced will be either positive or negative, which makes the view appear to shift in one direction or the other. To properly adjust the output of these values, you can use the Alpha Offset attribute to create a shift.

Set the Alpha Offset to negative one-half the Alpha Gain to get a range of values that are both positive and negative; 0 will be in the middle of this range. Figure 2.19 shows how adjusting the Amplitude, Alpha Gain, and Alpha Offset attributes affect the range of values produced by the animated fractal texture.

Figure 2.19. The range of values produced by the animated fractal texture can be adjusted using the Amplitude, Alpha Offset, and Alpha Gain attributes.

The best way to set this up is to create a simple expression where the Alpha Offset is multiplied by negative one-half of the Alpha Gain. This technique can be used any time you need to shift the range of the fractal texture's outAlpha to give both positive and negative values.

Select the fractal1 node and open its attributes in the Attribute Editor. Expand the Color Balance rollout and set the Alpha Gain of fractal1 to 0.25.

In the field for Alpha Offset, type =-0.5*fractal1.alphaGain;. Then hit the Enter key on the numeric keypad to enter the expression (Figure 2.20).

You can create the same setup for the fractal2 node. However, it might be a better idea to create a direct connection between the attributes of fractal1 and fractal2, so you need only adjust the Alpha Gain of fractal1, and all other values will update accordingly.

Figure 2.20. An expression is created to automatically set the Alpha Offset of fractal1 to negative one-half of the Alpha Gain.

In the Hypershade, MMB-drag fractal1 on top of fractal2, and choose Other from the pop-up menu to open the Connection Editor. On the left side of the Connection Editor, select alphaGain; on the right side, select alphaGain to connect these two attributes. Select alphaOffset on the left side, and then select alphaOffset on the right side to connect these two attributes. Select Amplitude on the left, and then select Amplitude on the right to connect these two attributes as well (see Figure 2.21).

Play the animation, and you'll see the camera shake. To tone down the movement, reduce the Alpha Gain of fractal1.

Set the timeline to frame 60, and set the Alpha Gain of fractal1 to 0. Right-click over the Alpha Gain field and choose Set key.

Set the timeline to frame 65. Set the Alpha Gain of fractal1 to 0.5, and set another key.

Set the timeline to frame 90. Set the Alpha Gain of fractal1 to 0, and set a third key. Play back the animation, and you'll see the camera shake as the car and helicopter fly by.

Save the scene as chase_v03.ma. To see a version of the scene to this point, open the chase_v03.ma file from the chapter2scenes directory.

Open the chase_v03.ma scene from the chapter2scenes directory on the DVD, or continue with the scene from the previous section. In the Display layers, turn off both the choppers and buildings layers.

Switch to the Persp camera in the viewport. Create a NURBS circle by choosing Create

Create a new camera (Create

Open the Attribute Editor for swivelCam to the swivelCamShape tab. Set the Controls to Camera and Aim.

Expand the new swivelCam_group node in the Outliner. Select the swivelCam and press the f hot key to focus on the camera in the viewport.

In the Outliner, select swivelCam and Ctrl+click the swivelCamRig circle. Switch to the Animation menu set, and choose Animate

Figure 2.22. The swivelCam is attached to the NURBS circle using the Attach To Motion Path command.

The camera is now attached to the circle via the motion path; the camera will stay in a fixed position on the circle curve. This is a fast and easy way to attach any object or other type of transform node (such as a group) to a curve.

Turn on the street and car display layers, and rewind the animation.

Zoom out in the viewport. In the Outliner, select the swivelCamRig and MMB-drag it up in the Outliner into the vehicleAnim group. Expand the vehicleAnim group, and select the swivelCamRig. Open the Channel Box, and set the Translate and Rotate channels to 0. The circle will be repositioned around the car.

Select the swivelCam_aim locator from within the swivelCam_group. In the Outliner, MMB-drag this up into the vehicleAnim group as well. Set its Translate and Rotate channels to 0. This will move to the pivot point of the vehicleAnim group.

Select the swivelCamRig, and in the Channel Box set Translate Y to 0.4. Set the Scale attributes to 0.5 (see Figure 2.23).

Set the viewport to the swivelCam, and turn on the Resolution Gate. Select the swivelCam node, and set its focal length to 2.. Play the animation.

In the Outliner, Ctrl+click the swivelCam node, swivelCamShape, the swivelCam_aim locator, and the swivelCamRig node. Choose Assets

Choose Assets

Figure 2.23. The NURBS circle (swivelCamRig) and the swivelCam_aim have been parented to the vehicleAnim group.

Figure 2.24. A container is created from nodes selected in the Outliner.

Click the plus sign in the square to expand the swivelCamera container, and then expand the swivelCam rig node (click the plus sign in the circle next to swivelCamRig). From the list of Attributes, select the Translate Y attribute. Click the second icon from the top at the center of the Asset Editor. Set the published name to rise.

Select the Rotate Y attribute, and publish it using the name swivel. Select Scale Z, and publish it using the name push.

Expand the swivelCam_aim node, and select its Translate attribute. Publish it using the name aim (see Figure 2.25). The three attributes Aim X, Aim Y, and Aim Z will be created at once.

Expand the swivelCam (click the plus sign in the square) and the swivelCamShape nodes (click the plus sign in the circle). Select the Focal Length attribute, and publish it using the name zoom.

Close the Asset Editor, and select the swivelCamera container node in the Outliner. Try changing the values of the published attributes and play the animation.

Lock Unused Rotation Channels

To cut down on rotation problems, you'll want to lock the Rotate X and Rotate Z values of the swivelCamRig. Select the node in the INPUTS section of the Channel Box, set the values to 0, right-click these attributes, and choose Lock Selected. This keeps the rotation nice and simple.

Figure 2.25. Various attributes are chosen from the nodes in the swivelCam container and published to the container using the Asset Editor.

Open the Preferences panel (Window

Set the view in the perspective window to swivelCam (Panels

Open the chase_v05.ma scene from the chapter2/scenes directory on the DVD. In the viewport, switch to the DOF_cam camera. If you play the animation (which starts at frame 100 in this scene), you'll see the camera move from street level upward as two helicopters come into view.

In the Panel menu bar, click the second icon from the left to open the DOF_cam's Attribute Editor. Expand the Environment settings, and click on the color swatch. Use the Color Chooser to create a pale blue color for the background (Figure 2.28).

Figure 2.28. A new background color is chosen for the DOF_cam.

Open the Render settings and make sure the Render Using menu is set to mental ray. If mental ray does not appear in the list, you'll need to load the Mayatomr.mll plug-in found in the Window

Select the Quality tab in the Render settings, and set the Quality preset to Preview:Final Gather.

Switch to the Rendering menu set. Choose Render

Set the timeline to frame 136, and Choose Render

The Render View window will open and render a frame. Even though there are no lights in the scene, even lighting is created when Final Gather is activated in the Render settings (it's activated automatically when you choose the Preview:Final Gather Quality preset). The pale blue background color in the current camera is used in the Final Gather calculations. More sophisticated environmental lighting is discussed in Chapter 10. This particular lighting arrangement is simple to set up and works fine for an animatic.

As you can see from the test render, the composition of this frame is confusing to the eye and does not read very well. There are many conflicting shapes in the background and foreground. Using Depth of Field can help the eye to separate background elements from foreground elements and sort out the overall composition.

Figure 2.29. A test render is created for frame 136.

In the Attribute Editor for the DOF_Cam expand the Depth Of Field rollout and activate Depth Of Field. Store the current image in the Render Preview window (from the Render Preview window menu choose File

Use the scroll bar at the bottom of the Render View window to compare the images. There's almost no discernable difference. This is because the Depth of Field settings need to be adjusted. There are only three settings:

Set the Focus Distance to 15, the F Stop to 2.8, and the Focus Region Scale to 0.1, and create another test render.

The blurriness in the scene is much more obvious and the composition is a little easier to understand. The blurring is very grainy. You can improve this by adjusting the Quality settings in the Render Settings window. Increasing the Max Sample level and decreasing the Anti-Aliasing Contrast will smooth the render, but it will take much more time to render the image. For now you can leave the settings where they are as you adjust the DOF. Render-quality issues are discussed in Chapter 12 (see Figure 2.30).

Save the scene as chase_v06.ma. To see a version of the scene so far, open chase_v06.ma from the chapter2scenes directory on the DVD.

Continue with the scene from the previous section or open the chase_v06.ma file from the Chapter2scenes directory of the DVD.

Switch to the perspective view. Choose Create

In the Outliner, rename locator1 camPosition and rename locator2 distToCam (see Figure 2.31).

In the Outliner, expand the DOF_cam_group. MMB-drag camPosition on top of the DOF_cam node to parent the locator to the camera. Open the Channel Box for the camPosition locator, and set all of its Translate and Rotate channels to 0; this will snap camPosition to the center of the camera.

Figure 2.31. A measure tool, consisting of two locators, is created on the grid.

Shift-select the camPosition's Translate and Rotate channels in the Channel Box, right-click the fields, and choose Lock Selected so that the locator can no longer be moved.

In the Outliner, MMB-drag distToCam on top of the camPosition locator to parent distToCam to camPosition. Select distToCam, and in the Channel Box set its Translate X and Y channels to 0 and lock these two channels (see Figure 2.32). You should be able to move distToCam only along the Z axis.

Figure 2.32. The Translate X and Y channels of the distToCam node are locked so that it can move only along the Z axis.

Open the Connection Editor by choosing Window

Expand the DOF_Cam node in the Outliner, and select DOF_camShape. Click Reload Right in the Connection Editor.

From the bottom of the list on the left, select Distance. On the right side, select FocusDistance (see Figure 2.33).

Figure 2.33. The Distance attribute of the distanceDimensionShape1 node is linked to the focusDistance attribute of the DOF_camShape node using the Connection Editor.

Look in the perspective view at the distance measured in the scene, select the distToCam locator, and move it so that the annotation reads about 5.5 units.

Select the DOF_camShape node and look at its focusDistance attribute. If it says something like 550 units, than there is a conversion problem. Select the distanceDimensionShape node in the Outliner, and open the Attribute Editor. From the menu in the Attribute Editor, click Focus, and select the node that reads unitConversion14. If you are having trouble finding this node, turn off DAG Objects Only in the Outliner's Display menu, and turn on Show Auxiliary Nodes in the Outliner's Show menu. You should see the unitConversion nodes at the bottom of the Outliner. Select unitConversion14 from the list to switch to the unitConversion node, and set the Conversion Factor to 1.

Occasionally when you create this rig and the scene size is set to something other than centimeters, Maya converts the units automatically, and you end up with an incorrect number for the Focus Distance attribute of the camera. This node may not always be necessary when setting up this rig. If the value of the Focus Distance attribute of the camera matches the distance shown by the distanceDimension node, then you don't need to adjust the unitConversion's Conversion Factor.

Set the timeline to frame 138. In the Perspective window, select the distToCam locator and move it along the Z axis until its position is near the position of the car (about −10.671). In the Channel Box, right-click the Translate Z channel, and choose Key Selected (see Figure 2.34).

Figure 2.34. The distToCam locator is moved to the position of the car on frame 138 and keyframed.

Switch to the DOF_cam in the viewport, and create a test render. The helicopters should be out of focus, and the area near the car should be in focus.

Set the timeline to frame 160. Move the distToCam node so it is at about the same position as the closest helicopter (around −1.026). Set another keyframe on its Z translation. Render another test frame. The area around the helicopter is now in focus (see Figure 2.35).

Open the scene chase_v08.ma from the chapter2scenes directory of the DVD.

In the Display Layer panel, right-click on the buildings display layer and choose Select Objects. This will select all of the objects in the layer. Open the Attribute Spread Sheet (Window

Switch to the Rendering menu set. Choose Render

Switch to the shotCam1 camera in the viewport. Set the timeline to frame 59, and open the Render View window (Window

Create a test render of the current view. From the Render View panel, choose Render

In the Render View panel, drag a red rectangle over the blue helicopter. To save time while working with Motion Blur, you'll render just this small area.

Open the Render Settings window. Switch to the Quality tab. Expand the Motion Blur rollout, and set Motion Blur to No Deformation. Leave the settings at their default, and in the Render View panel, click the render region icon (second icon from the left) to render the selected region in the scene. It will take a couple minutes. When it's finished, store the image in the render view. You can use the scroll bar at the bottom of the render view to compare stored images (see Figure 2.37).

Figure 2.37. The region around the helicopter is selected and rendered using Motion Blur. Just this small area took two minutes!

Immediately it should become apparent that Motion Blur adds a lot to render time, considering that this scene has no textures and simple geometry. It's true that Final Gather will add time to the render, but if you compare the time it took to render the full frame using the Final Gather Preview Render preset and the time it takes to render just a small portion of the frame with default settings, the difference is very significant. Clearly, optimizing Motion Blur is extremely important, and you should always consider balancing the quality of the final render with the amount of time it takes to render the sequence. Remember that if an object is moving quickly in the frame, some amount of graininess may actually be unnoticeable to the viewer.

In the Render Settings window, switch to the Features tab and set the Primary Renderer to Rasterizer (Rapid Motion) (see Figure 2.38). Click the Render Region button again to re-render the helicopter. This time it renders much faster. Store the image in the render view and compare it to the previous render.

Figure 2.38. Changing the Primary Renderer to Rasterizer (Rapid Motion) reduces the render time for the helicopter region to 12 seconds.

The Rapid Motion setting uses a different algorithm to render motion blur, which is not quite as accurate but much faster. However, it does change the way mental ray renders the entire scene.

If you render the buildings, you'll notice that the shading when you use Rasterizer (Rapid Motion) is different from when you use Scanline. The Rasterizer does not calculate motion blurring for ray-traced elements (such as reflections and shadows). You can solve some of the problem by using detailed shadow maps instead of ray-traced shadows (discussed in Chapter 9), but this won't solve the problem that reflections lack motion blur.

Switch back to the Quality tab and take a look at the settings under Motion Blur:

Render the region around the helicopter. Store the frame, and then set Shutter Open to 0.25 and render the region again. Store the frame and compare the two images. Try a Shutter Close setting of 0.75. Figure 2.39 shows the results of different settings for Shutter Open and Shutter Close.

Setting Shutter Open and Shutter Close to the same value effectively disables Motion Blur. You're basically saying that the shutter opens and closes instantaneously, and therefore there's no time to calculate a blur.

Return the Shutter settings to 0 for Shutter Open and 1 for Shutter Closed. In the Quality section below the Motion Blur settings, increase the Motion Steps to 6 and render the helicopter region again. Store the image and compare it to the previous renders. Notice that the blur on the helicopter blade is more of an arc, whereas in previous renders, the blur at the end of the blade is a straight line (Figure 2.40).

Create a new scene in Maya. From the Create menu choose Cameras

Switch the panel layout to Panels

Create a NURBS sphere (Create

In the perspective view, select the center camera, and open the Attribute Editor to stereoRigCenterCamShape.

In the Stereo settings you can choose which type of stereo setup you want; this is dictated by how you plan to use the images in the compositing stage. The interaxial separation adjusts the distance between the left and right cameras, and the zero parallax defines the point on the Z axis (relative to the camera) at which an object directly in front of the camera appears in the same position in the left and right cameras.

In the Attribute Editor, under the Stereo Display Controls rollout, set Display Frustum to All. In the perspective view you can see the overlapping angle of view for all three cameras.

Turn on Display Zero Parallax Plane. A semitransparent plane appears at the point defined by the Zero Parallax setting.

Set the Stereo setting in the Stereo rollout to Converged.

As you change the Zero Parallax value, the left and right cameras will rotate on their Y axis to adjust, and the Zero Parallax Plane will move back and forth depending on the setting.

Set the Zero Parallax attribute to 10 (see Figure 2.42). In the perspective view, switch to a top view and make sure the NURBS sphere is directly in front of the center camera and at the same position as the zero parallax plane (Translate Z = −10).

Figure 2.42. A stereo camera uses three cameras to render out an image for 3D movies. The zero parallax plane is positioned at the point where objects in front of the center camera appear in the same position in the left and right cameras.

In the top view, move the sphere back and forth toward and away from the camera rig. Notice how the sphere appears in the same position in the frame in the left and right camera view when it is at the zero parallax plane. However, when it is in front of or behind the plane, it appears in different positions in the left and right views.

If you hold a finger up in front of your eyes and focus on the finger, the position of the finger is at the zero parallax point. Keep your eyes focused on that point, but move your finger toward and away from your face. You see two fingers when it's before or behind the zero parallax point (more obvious when it's closer to your face). When a stereo camera rig is rendered and composited, the same effect is achieved and, with the help of 3D glasses, the image on the two-dimensional screen appears in three dimensions.

Turn on the Safe Viewing Volume option in the Attribute Editor. This displays the area in 3D space where the views in all three cameras overlap. Objects should remain within this volume in the animation so that they render correctly as a stereo image.

Open the Render settings to the Common tab. Under Renderable cameras you can choose to render each camera of the stereo rig separately, or you can select the stereo pair option to add both the right and left camera at the same time. Selecting the stereoCamera option renders the scene using the center camera in the stereo camera rig. This can be useful if you want to render a nonstereoscopic version of the animation.