STEP 1: Prepare your scene
Open a 3ds Max scene setup that features HDRI, global illumination, lots of geometry and separate light sources, and save it out in its final form with motion blur and depth of field turned off. This way, you’ll have a master scene to go back to and make the changes necessary for subsequent steps.
STEP 2: Render separate passes
Next, renderout this sequence with as many passes as you want – specular channel, RBG pass, Z buffer – and run these various elements separately, making sure that motion blur and depth of field are turned off. However, for the purposes of this tutorial, we’ll just assume you’re rendering a single beauty pass. Just repeat the following steps as necessary on all your separate channels if need be. NOTE: If you’re rendering out an RPF file format, you should NOT save out velocity channels so you can do post motion blur in Combustion. That’s not what we’re doing in this procedure.
STEP 3: Save Scene Versions
Now that you’ve got a render completed, the next thing you’ll do is take the scene and save it out under a different name, such as Scene_MotionBlur or Scene_DepthofField. This is the point where you’ll add motion blur, depth of field effects, or both, to your original render(s) from the previous steps.
STEP 4: Remove global illumination and HDRI
Remove all references in your render to any type of global illumination or HDRI. Turn all of that off. Turn off caustics and anything that isn’t a basic render. In fact, you can strip all of the image maps and lights out of your scene at this point, leaving only your render camera and the objects in your scene. I typically leave a single omni light set to 0 intensity in the scene to defeat Max’s default lighting, though there is also a setting to turn off the default lighting.
STEP 5: Create Materials
Open the material editor and add a bitmap to the diffuse map of an available material. Assign the image sequence created from your last, render without motion blurr or depth-of-field. Ensure that mapping is set to Explicit Map Channel, and set the map channel to 1. Increase the self-illumination value of the material to 100.
STEP 6: Add a camera mao modifier
Hit H on your keyboard and select all the objects in your scene. Add a camera map modifier ( WSM) to every object in the scene, and apply your newly created material to every object as well. Set the camera map ( WSM) to map channel 1 and set its camera to the one you rendered your original footage with.
STEP 7: Render final output
Now turn on motion blur and, if you’re using it, depth of field. Set up your render output to a new pass for your final output and render. Voila! Now you have a scene with global illumination, HDRI, caustic and any intense render effect computed with 3D motion blur and proper depth of field at a greatly reduced render time.
YOUR GUIDE
Matt Merkovich
Visuals Effects Artist
Digiscope
Matt Merkovich is a visual effects artist, currently heading up the 3D animation department of the Santa Monica-based Digiscope. VFX has been his forte since he was nine years old, directing stop-motion clay dinosaur movies and scratching laser beams into 8mm film with a razor blade. You can contact him at mattmerk2000@hotmail.com.
Matt Says Keep in Mind…
Dog-slow renders are the bane of an animator’s existence. Yet the most beautiful, dramatically lit, photo-real scenes demand long render times regardless of the renderer or application. A typical 3ds Max scene that uses HDRI (high dynamic range images), global illumination, with lots of geometry looks beautiful, but takes a really long time to render at final quality settings. When depth of field and motion blur are added to this type of scene, there can be serious bottlenecks. To greatly speed up final scene renders, I use this technique. This trick is renderer-agnostic and can be applied to any 3ds Max-supported rendering solution. It won’t work, however, if your scene includes objects with flat planes where you’re using an alpha channel to cut portions of that polygon away and it’s not going to calculate motion blur properly for scenes with layers of transparency. Overall, though, this technique should work out for you just fine.
Digiscope
www.digiscope.com
2308 Broadway
Santa Monica, CA 90404
ph. 310.315.6060
info@digiscope.com
Support Gear
The Turbosquid model used for this tutorial was created by Rune Spaans.