Rendering

18

Preview Rendering

Before you perform a final render, you will want to preview the appearance of objects, shaders, textures, and lights using one of the preview renderers. Preview rendering is typically faster (and lower quality) than final rendering. Preview renderers include Quick Render, Direct Render, Fast Render, Sketch Render, and Modeler Wire.

In This Section:

• Quick Render 362
• Direct Render 371
• Fast Render 374
• Sketch Render 391
• Modeler Wire 393

Quick Render

Quick Render renders a preview-quality image for the active window that can include shaders, textures, lights, and the environment, as well as shadows, particles, and animation. Quick Render is faster than "real" rendering because it samples a scene once per vertex, instead of once per pixel.

You can Quick Render a window for a one-time preview of your scene, or you can use Quick Render in persistent mode to let you easily update this preview as you make changes to your scene. Using Quick Render in persistent mode is an effective compromise between working in wireframe and shaded modeling modes.

Quick Render has the following limitations:

• In Quick Render, "faces" (created with the Planar tool) will render unpredictably unless the face is a single component, is built from co-planar curves, and contains no crossing holes.

• Quick Render only calculates shadows from spotlights.

• Quick Render does not render glow in orthographic views.

• Quick Render does not render shader transparency, reflection, or refraction. However, Quick Render does approximate transparency maps.

• Alias calculates ambient shading differently than conventional methods.

Conventionally, ambience is constant (reduced only by the diffuse component of the surface)-a sphere with only ambient shading would look like a flat disk.

To avoid this, Alias makes the ambient shading a function of the surface normal and the eye vector, in addition to the diffuse component of the surface.

If you want conventional ambiance, set the Ambient Shade parameter of the ambient light to 0 (see Ambient Shade on page 268).

Using Quick Render

To perform a Quick Render:

1

Select the modeling window you want to Quick Render.

You can also perform a Quick Render by selecting Shading > Quick Render from within the Multi-lister. See Quick Render on page 31.

2

Select Render > Quick render.

The Quick Render window appears on top of the active window.

To stop the Quick Render before it is completed, press Esc.

See Persistence on page 370 and Tgl Persistence on page 366.

To control whether the Quick Render window closes (when you click it) after one Quick Render or remains open (and updates when you click it), set the Persistence option in the Quick Render Options window, or the Tgl Persistence option in the Quick Render window options menu.

To redraw the Quick Render window, click in the window. To redraw a limited area within the Quick Render window, click-drag a box around the area in the Quick Render window that you want to update. If you have already drawn a bounding box in the window, click inside the box to redraw within the box, or click outside the box to redraw the entire window.

To adjust the quality and the redraw speed of the Quick Render window, move the render quality slider on the right side of the Quick Render window, then click in the window to redraw the scene at the new setting.

See Shader Monitor on page 367.

To control whether the Quick Render window automatically updates only affected parts of the Quick Render when you edit a shader, set the Shader Monitor option in the Quick Render window's options menu.

To close the Quick Render window:

• Click anywhere in the Quick Render window, or click the close icon in the top left corner of the Quick Render window. If Persistence is ON, you can only close the Quick Render window by clicking the close icon.

To open the Quick Render options window:

• Select Render > Quick render .

To record a Quick Render animation to a video device:

1

Select Render > Quick render to open the Global Quick Rendering Parameters option box.

The QuickRender/Record option box only appears if you have tape editing hardware available and properly installed.

2

Set Record ON. The QuickRender/Record option box appears.

VTR device, FBD device

The VTR (Video Tape Recorder) or FBD (Frame Buffer Device) to record to.

Center

Centers the image during recording.

Fit

Scales the image to fit the selected VTR or FBD device.

TimeCode/Frame

The time code frame number on the tape to begin recording. For example, if TimeCode/Frame is 00:10, the Quick Render will begin recording ten minutes into the tape.

3

Set the QuickRender/Record options and click OK.

For information on using video recording devices, see Using Video in the Complementary Applications book.

Quick Render Window

Resize Menu

Size From Globals

Resizes the Quick Rendered image based on the X Resolution and Y Resolution values in the Render Globals window (see X Resolution, Y Resolution on page 414).

Size From Window

Resizes the Quick Rendered image based on the modeling window that was active when you selected Quick Render.

Options Menu

Render Control

Toggles the render status display in the prompt line. Selecting Render Control acts the same as selecting DisplayTgls > Render toggles > Render status.

Render Globals

Opens the Render Globals window (see Render Globals Window on page 396). Selecting Render Globals acts the same as selecting Render > Globals.

Save to Image

Saves the Quick Rendered image as an Alias pix file.

Tgl Persistence

Toggles the persistence of the Quick Render window. If Tgl Persistence is ON, the Quick Render window will remain open while you continue to work in the modeling windows, until you click the Quick Render window's close icon. If Tgl Persistence is OFF, a mouse click will close the Quick Render window and return you to the wireframe view.

Lock Source Window

Displays the Quick Render for the source window (the window that was active when you activated Quick Render) whenever you update the Quick Render window (for example, if Persistence or Tgl Persistence is ON and you click in the Quick Render window). If Lock Source Window is OFF, and you update the Quick Render window, the Quick Render window displays the Quick Render for the active window.

Active Objects

Renders only objects that are picked in the modeling windows.

Background

Renders the background environment. After selecting Background, set Tgl Persistence ON and click in the Quick Render window to redraw the scene with the background.

Save Geometry

Keeps the tessellation of NURBS surfaces in memory to provide a faster display (at the expense of using more memory). The next time Quick Render refreshes, it can skip the tessellation phase.

Turbo Assist

Uses hardware shaders and lights to speed up the Quick Render when possible. After selecting Turbo Assist, set Tgl Persistence ON and click in the Quick Render window to redraw the scene.

Shader Monitor

Automatically updates affected parts of the Quick Render whenever you edit a shader. Quick Render uses the z-buffer to only redraw the pixels of the shader, without having to redraw the entire scene.

Flat Shading

Disables the smoothing algorithms and displays surfaces using flat-color polygons. After selecting Flat Shading, set Tgl Persistence ON and click in the Quick Render window to redraw the scene.

Quick Render Options

To open the Global Quick Rendering Parameters option box, select Render > Quick render .

Quality

Controls the quality of the Quick Render (Low, Medium, or High) by setting the number of subdivisions if Subdivision is set to Global. The Quality setting does not affect final renderings.

Render

Determines whether all objects (All) or only selected objects (Active) are displayed during Quick Rendering. The default setting is All.

Subdivision

Determines whether the Quality setting's global subdivision parameters (Global) or individual objects' subdivision parameters (Per Object) are used to subdivide objects during Quick Rendering. The default setting is Per Object.

Particles

Determines whether particles are displayed during Quick Rendering. The default setting is Fast.

Off	particles are not displayed
Fast	particles are displayed at draft-like low quality
Full Render	particles are displayed at full render, high quality

Flat Shading

Disables the smoothing algorithms and displays surfaces using flat-color polygons. One normal of each triangular facet represents the triangle, giving objects a faceted appearance. When Flat Shading is OFF, objects are smooth shaded.

Background

Displays the background environment. If Background is OFF, the Quick Render displays the scene's wire background.

Shadow Pass

Performs a shadow pass calculation (if any shadow casting spotlights exist) and displays shadows produced by shadow casting spotlights. You may need to increase Shading Frequency to better view shadows.

Output Image

Saves the Quick Rendered image as an Alias pix file.

Turbo Assist

Uses hardware shaders and lights to speed up the Quick Render when possible.

Textures

Displays textures on surfaces. The default setting is ON. You may need to increase the Shading Frequency value to better view textures.

Animation

Quick Renders every frame of an animation. If Animation is OFF, only the current frame is Quick Rendered.

Glow Pass

Performs a glow pass calculation (if any light or shadow glows exist), and displays light and shader glows.

See To record a Quick Render animation to a video device: on page 364.

Record

Lets you record the Quick Render to a video tape recorder or frame buffer device.

Persistence

Lets the Quick Render window remain open while you continue to work in the modeling windows, until you click the Quick Render window's close icon. If Persistence is OFF, a mouse click will close the Quick Render window and return you to the wireframe view.

Shading Frequency

The frequency of shading samples taken per patch. By increasing Shading Frequency, you increase the quality of the Quick Render (without increasing the number of surface subdivisions). You may need to increase the Shading Frequency value to better view shadows, or surfaces with textures or high specularity. The slider range is 0 to 10. The default value is 0.