INSIDE 3DS MAX® 7 [Electronic resources] نسخه متنی

The Render Scene Dialog

For the real deal, you need to "Production render" your scene. To get to the Render Scene dialog (Figure 19.3), you can either choose Render from a Rendering menu, or click the Render Scene button.

This section may read as somewhat tedious; however, it was written to help someone troubleshoot a bad render. Even though you would never thrash around with unknown settings, it may become your responsibility to fix files created by colleagues complaining of malicious elves or stray cosmic rays.

The Common Panel

In this panel, we start with the Time Output section. This is where you set up still or animation rendering. The options are pretty much self-explanatory, but there are a couple of things you should note. The Every Nth Frame parameter enables you to skip frames in your animation, a real boon when you want to test a long, complex render. The other option of note is File Number Base. This tells the renderer where to start the numbering of sequential stills, after which it will increment the frame count by one, as usual. The most common use of this is to start the rendering on frame 0001, instead of 0000. That way, if you want to render 60 frames, your last frame will be frame 0060. Otherwise, it would be frame 0059, as there is a frame 0000 at the beginning. This saves a lot of confusion when compositing or editing, as the frame counts in other software will line up properly with your rendered frames. Starting from frame 0001 may not seem like such a big deal, but having to constantly add or subtract 1 to figure out which frame is which will cause at least a few errors at some point in the production.

The Output Size section is far more than a mere designator of the pixel width and height of the finished rendering. It's also where you do the final step in matching real-world cameras, an exercise that we'll get into later in the chapter.

The output sizes are the function of a premeasured width and height (which make up the Image Aspect), the Pixel Aspect (the pixels' squareness), and the Aperture Width (the "lens" on the "projector"). By locking Image Aspect, you can quickly go from rendering a file 640 by 480 pixels to one 1280 by 960 by changing only one of the numbers; the other figure is adjusted in proportion automatically. If you have a favorite image size for your renders, you can change any of the presets by right-clicking them.

The Options section of the Render Scene Common panel contains these check boxes:

• Atmospherics
  For using Fog, Volume Fog, Volume Lights, and Fire effects in a scene. Atmospherics will be covered in detail in the next section.

• Effects
  Controls Lens effects, Blur, Brightness and Contrast, Color Balance, Depth of Field, File Output, Film Grain, and Motion Blur.

• Displacement
  Turns on and off any displacement mapping in the scene. Displacement mapping creates polygons on the fly, which can have dramatic results on rendering speed.

  Note

  Turning off the previous three entries can give your rendering a speed boost when you're troubleshooting a scene. Be sure to write a note to yourself, as it's easy to forget to turn them back on!

• Video Color Check
  Flags any pixels that would be beyond the normal limits of PAL and NTSC colors (see the definitions in the beginning of the chapter). Normally, these pixels are rendered black, but this can be changed in the Rendering panel of the Preference Settings dialog. Strong, bright reds are especially prone to bleeding and can be spotted readily with this check.

• Render to Fields
  Field renders sequential images, which helps to display animation on a non-interlaced television monitor. Only odd-numbered lines are drawn in one line, and even-numbered lines in the next. This can help to eliminate pixel popping and sizzling, but can also have undesirable dropout side effects. It's best if done from the editing or compositing program. Field order is set in the Customize > Preferences > Rendering dialog. The field order in 3ds max must match the field order in the editing program; otherwise the video will vibrate.

• Render Hidden Geometry
  Renders all geometry in the scene, whether hidden or not. Note that if the Renderable flag is turned off in the Object Properties dialog, the geometry won't render.

• Area Lights/Shadows as Points
  Renders all Area Lights and Area Shadows as if they were single-point light sources. This can improve rendering speeds, but will degrade cast-shadow quality.

• Force 2-Sided
  A handy option if your objects have strange holes (especially objects imported as .dfx files), as if they were missing polygons. Force 2-Sided slows rendering time, and is a Band-Aid-type fix. Ideally, the models should have their normals unified and facing in the proper direction.

• Super Black
  An option used primarily to help compositors to differentiate a very dark object from the background. The threshold is set in the Customize > Preferences > Rendering dialog.

Typically, Options are left at the defaults, but it never hurts to confirm the settings before a long render. The Use Advanced Lighting box is usually left checked, as the Advanced Lighting is selected in its own panel. Changing this will not affect render time if no Advanced lighting has been selected.

Tip

You may have to place the cursor over an unused section of the dialog to get the Hand, and scroll the dialog up to see the rest of the dialog.

The Render Output File dialog is where you specify the type and location of files to be saved. Access it by clicking the Files button. 3ds max can save in the following formats:

• .avi
  Audio Visual Interleave, a Windows animation format. You must have the necessary codec loaded into your system.

• .bmp
  Windows bitmap. Supports 8-and 24-bit formats.

• .cin
  Kodak's Cineon. This 10-bit-per-channel format is a subset of the ANSI/SMPTE DPX file format. Used with high-end film-compositing systems.

• .eps, .ps
  Encapsulated PostScript. A good format for prepress systems. The settings allow you to establish page size and resolution. See the "Print Size Wizard" section at the end of this chapter for more details.

• .flc, .fli, .cel
  A legacy Autodesk Flic format used for limited-palette animations and stills.

• .hdr, .pic
  Radiance formats for HDRI (High Dynamic Range Image) files. Great for background environments but difficult to use.

• .jpg, .jpe, .jpeg
  A lossy compression scheme that produces a very small file.

• .mov
  QuickTime animation.

• .png
  Portable Network Graphics. Image files can have 48-bit (281 trillion) colors and built-in transparency.

• .rgb, .sgi
  Silicon Graphics image file format.

• .rla
  Wavefront raster image format. These files enable you to save additional channels of information, such as object IDs, material effects channels, and Z-depth info. Especially useful for compositing.

• .rpf
  An extended version of .rla, with more options for channel export. A primary means of sending files to discreet's combustion compositing software.

• .tga, .vda, .icb, .vst
  Targa image file format. The "vanilla" format that almost all software can interpret. A lossless compression is available as well as alpha channel support.

  Note

  You should always leave the Pre-Multiplied Alpha option checked. This feature takes into account whatever background is in place, and anti-aliases against it. Turning it off will result in a case of the jaggies.

• .tif
  Tagged Image File Format. Good for prepress use with assignable dot-per-inch values.

• .dds
  Microsoft's DirectDraw Surface format. Used by game engines to display variable-resolution images (mipmaps).

Note

MPEG (.mpg) files can be input as textures but not output as renderings.

Carefully consider the file type of your output, as there can be serious consequences for your files down the road. A brief discussion with colleagues (and even a quickly rendered sample) can head off lengthy rerenders.

3ds max can also render to an external device, such as a film recorder. Clicking on the Devices button in the Render Output area will bring up a list of any installed drivers for these devices.

The last three features in the Common Parameters rollout are Rendered Frame Window, which allows you to display each frame as it renders; Skip Existing Images, which enables you to skip the images already rendered in a sequence; and Net Render, which turns on Network Rendering.

For those times when you can't be at your machine, you can have it e-mail your PDA with the latest render news. The Email Notifications rollout just below Common Parameters in the Render Screen dialog can be set up to let you know about failures, progress, or completion. By combining this with an email-to-pager gateway, you could get a page if your render goes down. The company Corybant offers the IVEENA Priority Voice Email, which will do same thing with a call to your cellular phone. This gives a whole new meaning to the concept of being on "render wander."

Assign Renderer, the final rollout, allows you to assign mental ray (or any other installed third-party renderers) as your default Production renderer.

Once you've taken the time to set up all of these parameters, they can be saved to a Preset file at the bottom of the dialog. This will help to maintain consistency throughout the rendering process, and make the switch from test renders to final production shots an easy one. There are a number of Rendering Presets provided for you in the dropdown menu to get you started.

The Renderer Panel

As if the Common panel didn't have enough settings, we move on to its next-door neighbor, the Renderer (Figure 19.4).

The top set of options is primarily used to speed up test renders, and for troubleshooting problems. As with the Options and Advanced Lighting sections in the Common panel, writing yourself a reminder of which boxes were checked can save you (or a colleague) considerable grief at that final render.

When the Enable SSE box is checked, the renderer uses streaming SIMD extensions. If you have a Pentium III or better CPU (including Celeron and AMD with 3dNow), using SSE can help speed up renderings. SSE takes advantage of the floating-point precision designed into 3ds max. The default is the unchecked box.

Anti-aliasing

Anti-aliasing removes the jagged edges from diagonal and curved edges and lines. For the most part, leaving the Filter default at Area will produce acceptable results (Figure 19.5). The anti-aliasing of a rendering is what establishes its "look and feel"; it can be used artistically to enhance the fantasy of a scene or bring it into hard-edged crispness. A softer method can give a dreamlike feel, whereas a harder method is better for architectural prints.

3ds max offers a variety of anti-aliasing choices. Blackman is very crisp and can be used to mimic a Lightwave 3D rendering. The Catmull-Rom method is a nonproprietary (and scaled-down) version of the method that Pixar uses in its PhotoRealistic RenderMan product. The Video method produces a soft edge, and it's great for compositing with live video, even though it might look a bit fuzzy in your rendering. As live video is blurrier than a 3D rendering, this method can help get a better match. As with all settings in 3ds max, you should always do a test render of your scene and take it through the rest of the production process. The effects are subtle and somewhat difficult to see in the printed form. You can open the folder AAtests on the DVD to see some examples.

Supersampling

Supersampling is an additional anti-aliasing pass made on the maps assigned by the Material Editor. It's primarily used when blurry artifacts spoil a very detailed texture. Artists concerned primarily with output to video or game development need not concern themselves with supersampling, as it is a time-costly effect that will never be seen.

For a product designer or an architectural renderer, it could make or break the final illustration. Even though the master control for supersampling is located in the Renderer panel, it is best controlled on a material-by-material basis. Due to the additional time hit, you typically wouldn't want to supersample the entire scene (Figure 19.6). Turning it off can be useful for rendering quickie tests, but remember to turn it back on! You'll find examples of supersampling in the SS tests folder on the DVD.

Note

Using small texture maps negates any benefit from the supersampling due to the inherent blurring. A lossy compression format, like .jpeg, will also render supersampling useless.

The final areas of the Renderer panel deal with the Rendering Iterations of automatic reflection and refraction maps (Auto Reflect/Refract Maps); Color Range Limiting; and Memory Management. Rendering Iterations refers to the number of rendered inter-object bounces. If you have a mirror surface, the default of 1 is fine. If there is a mirror ball on this reflective surface, you would have to increase this value to 2 for both reflections to be seen.

3ds max has two methods of limiting out-of-range colors, like those in a very bright specular highlight. Clamping puts a limit on the intensity, while scaling drops the whole value of light in the scene. The Color Range Limiting default, Clamp, is usually the best.

If you find that you are consistently running out of RAM, you really should buy more. The Conserve Memory option will save only 10 to 15 percent, and it will give you a 5 percent hit on rendering time.

Note

Once 3ds max starts to page out to virtual memory, it will continue to do so until the program is restarted. This substantially slows down subsequent renderings.

The Raytracer Panel

3ds max uses a fairly elegant raytrace implementation in the Default Scanline Renderer, in that the raytracer is called into play only when necessary. Therefore, turning it off will not give you a speed increase unless you are using Raytrace Materials, Raytrace Maps, Advanced Ray Traced Shadows, or Area Shadows.

Notice in Figure 19.7 that raytracing has its own form of anti-aliasing, and it is currently turned off. This anti-aliasing pass deals with the images presented by reflections and can substantially increase render time. In many cases, the anti-aliasing problems are dealt with adequately in the primary rendering pass or are made inconsequential by any motion blur applied. If your scene involves a close-up with a raytraced mirror reflection, at least the final hold-frame should have anti-aliasing applied to the Raytrace Material.

Ray Depth Control tells 3ds max how many times to bounce light rays around in the scene. In most cases, the ray comes from the light source, bounces off the object, and strikes the camera "lens." When objects reflect themselves, a practical limit needs to be placed on the number of reflections.

In Figures 19.8 and 19.9 on the next page, the Maximum Depth has been altered to illustrate this concept. Note that when the reflections run out, the image is replaced with the background color.