Optimize Ray Tracing for frame rate or quality

Why there is a trade off between frame rate and quality

Interactive Ray Tracing, like Hardware rendering, displays the scene interactively by rendering the entire image frame over and over at a specific quality level. This “framerate” is typically many times per second, but will decrease as more rays are traced into the scene or as the number of samples per pixel (the smoothness) is increased. In general, a high quality image with many effects takes significantly longer to create and display than a very basic ray traced image with limited quality.

The number of rays traced per pixel is based on the visible ray tracing effects (shadows, global illumination, etc.), and on the material characteristics (transparent, reflective, etc.) of the objects in the scene. The Performance and Quality ray tracing Quality presets control many of these factors at once.

Tips for Ray Tracing performance and quality

Improving interactive performance

1. Reduce the Showcase window size. Ray tracing is based on tracing rays from each pixel of the image, so reducing the number of screen pixels will increase the frame rate and any progressive refinement of the image on screen.
2. In the Options > Selection Display Style menu, select a “wireframe” display method. The “animated grid” will prevent progressive refinement.
3. Move the view away from areas with lots of transparent and refractive surfaces. Transparent and inter-reflective objects will require more rays per pixel than other objects in the scene, and will reduce performance when they are dominant in the view.

Ray Tracing Status and Control Panel

The Ray Tracing Control Panel floats in the lower, right corner of the screen and shows feedback on the Interactive Ray Tracing progress, and provides quick access to Ray Tracing Settings and saving the on-screen image.

To open the Ray Tracing Control Panel, select Appearance > Ray Tracing Control Panel or press the Y key.

Progress bar

A horizontal bar shows the current Interactive Ray Tracing progress between sampling settings, along with helpful diagnostic information. The Progress bar includes:

• Elapsed time: the elapsed time from the last Interactive Ray Tracing restart in “hours: minutes: seconds” format.
  Note

  The Interactive Ray Tracing progress will restart when any visual change takes place in the scene. This could be a camera movement, material adjustment, a change to the Ray Tracing quality preset, or many other actions.

• Percentage Done: How far the rendering has progressed toward the chosen level in the Refine Image panel of the Performance and Quality window. If the render level is set to forever, percentage is shown as two dashes (--).
• Render Levels: The number of render levels performed to this point.

Save (current screen image and settings)

Pressing the Save button in the Ray Tracing Status control panel will save the current image on screen to disk along with the ray tracing settings needed to reproduce it in a companion XML file.

To save the current screen image with a settings file:

1. Deselect any objects with Ctrl+Shift+A.
2. Press the Save button when the on screen image is desired.
3. Browse to a location on disk to save the image and the Settings XML file.
4. Enter a unique name for the image and settings and choose either JPEG or TIFF as the output format.

Use Saved screen image settings as a quality preset

The Saved screen image quality preset XML can be used to reproduce the exact quality level seen in that image for a larger image or animation.

1. Locate the saved settings XML file on disk. (It is saved in the same location as the screen image, with the same name appended with “.xml”)
2. Move this XML file to the My Documents\Autodesk Showcase 2014\InteractiveRaytracingSettings folder.
3. Close and reopen the Performance and Quality or Publish windows.

   The new preset will be shown in the list of Quality presets in all windows, and can be used to recreate the exact quality level.

   Note

   A saved screen image Quality Preset XML file is not recommended for Interactive Ray Tracing. Such a preset disables progressive improvement, so rendering of the image on screen will continue until the desired render level is reached.

Settings (for Interactive Ray Tracing)

Press the Settings button to open the Performance and Quality window to the Interactive Ray Tracing tab. If the window is already open, it will switch to the Interactive Ray Tracing tab.