LightWave 3D 8 1001 Tips & Tricks phần 6 docx

659 Policarpo | General Tips | Beginner Train Your Eye It helps to train one’s eye by studying paintings by the great masters like Caravaggio, Vermeer, Rembrandt, and others. Any book on art history will pro - vide you with ample examples of how painters have learned to depict reality via the play of light and shadow. This is another good reason to use the Google Image Search function to build up your library of reference material. When you find an image that inspires you, go about recreating it in 3D so that you come to a better understanding of what it takes to achieve a particular look. Versions: All 660 Policarpo | General Tips | Beginner Test Lights Set up a basic scene and test out the different light types and properties for these lights in LightWave. See what the different falloff modes do to the power and quality of light in your scene. Create a default scene filled with interesting objects that you can reuse during your testing and experimentation process. Versions: 6-8 661 Lee Stranahan | General Tips | All Levels Turn Ambient to Zero; Except When Radiosity Is On It’s a pretty common hint to turn ambient intensity down. I say turn it to zero, period. Why? Because it’s evil, that’s why. It’s nondirectional, additive light — that means it makes all your objects slightly brighter. This is useless. It’s like a brightness control, and it adjusts your black point higher. As I said — evil. If you want ambient light, toss in a distant light at a low level. Except…when radiosity is turned on, ambient intensity becomes a different thing. Now, it adjusts the level of radiosity bounce and it’s a good thing, indeed. In fact, it’s often useful to crank it up to 20, 40, 60% — levels nobody in their right mind would use with regular ambient light. Versions: All 662 Geoffrey Kater | General Tips | Beginner Ambient Intensity Set Ambient Intensity to 0% in the Global Illumination panel. Use a distant light or spotlight to create more realistic reflected light. You can open it by clicking the Global Illumination button at the top of the Light Properties dialog (tap “L” then “p”). Versions: 5-8 Lighting | 297 General Tips 663 Eki Halkka | General Tips | Intermediate Recreating the Sun Even though the sun is a huge luminous gas ball, it’s also very far away and it only covers a small portion of the sky. So it can be considered a small light source in relation to your scene. As the sun is extremely far away, it also has a unique property not often seen in other, worldly light sources: Light rays coming from the sun are, in practice, parallel. Shadows cast by the sun grow very little over distance. LightWave’s distant light mimics these properties. It can be thought of as an infinitely small light source, infinitely far away. For many scenes, this is a good enough approximation for a sun. But if you wish to take your render a step further, you should take into account the fact that the sun is not a pinpoint light source. A distant light’s shad - ows are always hard. Even though the sun’s shadows don’t grow much bigger over distance, they do get a bit softer. The soft edges, called penumbra, appear where the shadow-casting object blocks the light source, the sun, only partially. You can try using a shadow-mapped spotlight, shining from very far away. This will give you softer shadows, but their softness is constant regardless of the dis- tance from the shadow-casting object. There are a few ways to do more realistic shadows. Maybe the most accurate way is to use an area light, moved very far away and scaled so that its size is approximately the same as the real sun’s perceived size, relative to the scene. Another way is to use multiple distant lights, each with their rotation slightly offset from each other and casting their shadows in slightly different directions. When you have enough of these lights, their shadows will blend together into one soft-looking shadow. You can use the spinning light trick to multiply the apparent number of these lights by the number of antialiasing passes, or even create the same result with a single distant light. Versions: 6-8 664 Policarpo, Eki Halkka | General Tips | Intermediate Spinning Light Trick Use the spinning light trick to simulate GI. To get smoother shadows, just use a higher AA setting. LightWave calculates motion blur by rendering a different time step at each antialiasing pass and combining these to a single image. If the Antialiasing set - ting is low and there’s fast motion in the frame, a series of ghost images can be seen. The spinning light trick uses this phenomena to multiply the apparent number of lights in the scene. When a high enough Antialiasing setting is used, the shadows from the lights blend together, giving the appearance of a single soft shadow. With a basic spinning light setup, the goal is to make the light rotate a full revolution, 360º, during the antialiasing passes. LightWave’s default motion blur length is 50%, so to get 360º of rotation, the light has to turn 720º each frame. One way to create spinning light rigs is by using Overcaster from Eki’s PlugPak. 298 | Chapter 7 General Tips When the user runs an Overcaster script, the script first reads some parameters from the scene. The most important is the motion blur length of the current cam - era. If the user has set the motion blur to, for example, 5%, the amount of spinning must be increased to 7200º to get a full revolution during the antialiasing passes, as the desired 360º is 5% of 7200. With high antialiasing and normal motion blur, a single spinning light will shine from 17 different positions. There’s no difference in render time compared to a regular light. Follow these steps to create a global illumination rig with spinning lights: 1. Create a hemisphere object and hit “f” to flip the polygons. 2. Create a Luxigon object via Setup>Layout Tools. 3. Select the Light Type and set the Color and Intensity options. (You can use any type of light you wish, but I prefer ray-traced shadowed distant lights.) Lighting | 299 General Tips 4. Send the scene to Layout and select your Hemisphere object. 5. Select the Convert Luxigons item from the Items>Lights drop-down (use Utilities>Additional in LW 7.5), and name your light rig set accordingly. Your light rig is created. 300 | Chapter 7 General Tips 6. Select the Hemisphere polygon object. In the Object Properties panel, select the Render tab and check the following: Unseen by Rays, Unseen by Cam - era, and Unaffected by Fog. This will ensure that it does not appear in the final render. 7. In LightWave 8, use the Scene Editor to multiselect your lights. (This is only available in LW 8.) Lighting | 301 General Tips 8. Right-click and choose Select in view ports from the drop-down. 9. Adjust any settings you want to alter in the Light Properties panel, changing light and shadow types and doing a series of render tests until you achieve the look you want. 10. Select the parent object for your light rig. Go to frame 1 and set the Heading field to 60º (720/12, the number of sides in the hemisphere). 11. Open the Graph Editor and select the Heading channel. Select Repeat from the Post Behavior drop-down. 302 | Chapter 7 General Tips 12. Set Antialiasing to Enhanced Low or higher and activate Dithered in the Motion Blur drop-down. 13. Activate Ray Trace Shadows in the Render Options panel. Lighting | 303 General Tips The look and feel of GI without the render time hit. Notes on optimizing a scene: n Reduce the number of luxigons you use by using less geometry during setup. n To smooth your ground plane shadows, increase your AA settings. n Use multiple colored lights in your scene to enrich the color space of the final render. n Use one key light to drive your primary shadow in your scene. Versions: 7.5-8 665 Eki Halkka | General Tips | Intermediate Creating a Sun Here’s how to create a basic spinning distant light sun. 1. Start with a new, empty scene. Take the default distant light and rename it “Sun.” Reset its motion and rotation. 2. Add two nulls to the scene and name them “Sun_handle” and “Sun_spinner.” Parent (“m,” parent item drop-down) the spinner null to the handle and the distant light to the spinner. 3. Go to frame one and rotate the spinner null’s bank 720º. Create a keyframe (Enter). Open Graph Editor (Ctrl+F2) and select the bank rotation channel. Set Pre and Post Behavior to Repeat. 4. The more you rotate the sun light, the bigger the light source’s simulated diameter and softer the shadows. Rotate the sun light by 0.5º at frame zero on heading or pitch to roughly match the sun’s diameter, as perceived here on earth. 5. You can now rotate the handle null to aim your sun, treat the null as if it were the distant light itself. The spinning light trick is done, but there’s one more thing to do. As the spinning light trick relies on LightWave’s internal motion blur calculations, you will need to turn it on in the Camera Options panel (Shift+C, p). Usually a sun will look good enough with low 304 | Chapter 7 General Tips Spinning spotlights with shadow-mapped shadows and four distinct light colors. antialiasing and normal motion blur, but if you make the spinning light softer, you will need to use higher settings. For more information on spinning lights, see: http://members.shaw.ca/phroggrafix/tutorials/spinning/spinning.html http://www.kolumbus.fi/erkki.halkka/plugpak/Tut/OC_Behind.html http://members.shaw.ca/lightwavetutorials/lighting.htm I have created a collection of LScripts that automate the creation of a variety of spinning light rigs ranging from a basic sun similar to the above to a full global illumination setup. Have a look; you can use the scripts for free, as long as you don’t mind a few nagging requesters! (http://www.kolumbus.fi/erkki.halkka/plugpak/index.html) Versions: 6-8 666 Dave Jerrard | General Tips | All Levels Project a Procedural through a Spotlight You can project a procedural texture through a spotlight using the Projected Image feature. The trick is to open an image in the Image Editor and then apply the Textured Filter plug-in. This will allow you to texture the image as though it were a surface. By applying a procedural like Ripples or Underwater, you can have an animated procedural texture applied to the image, which would also ani- mate when it’s projected through a spotlight. It’s a good idea to use a large image since the procedural texture will be bitmapped when it’s projected, and the resolution will be the same as the image you’re using. Use a large image that only has one bit plane (two colors) to get the largest resolution without eating up a lot of RAM. Lighting | 305 General Tips The following is a large 2000 x 2000 pixel image that has an Underwater procedural applied. When this image is projected through a spotlight, it creates an animated underwater effect. Versions: 6.5-8 667 Dave Jerrard | General Tips | All Levels Shading Noise Reduction If you’re using linear or area lights (or even shadow maps), radiosity, or caustics, you might want to turn on the Shading Noise Reduction option in the Global Illumination panel. This was added to help reduce the grain that fre - quently appears in images using these features. On a typical frame it will add 5 to 10 seconds of render time to the end of each render pass. What it really does is perform a small blur to the shading buffer (which you can view separately using the Render Buffer View image plug-in and the Image Viewer). However, this can blur out small texture details, such as those caused by fine bump maps, so you’ll have to determine whether to use it on a scene-by-scene basis. Versions: 6.5-8 668 Dave Jerrard | General Tips | All Levels More on Shading Noise Reduction Shading Noise Reduction can also be used to subtly soften ray-traced shad - ows cast by distant, spot, or point light sources. Again, this may have detrimental effects to fine textures, so you’ll have to test this for each scene. Versions: 6.5-8 306 | Chapter 7 General Tips [...]... necessarily subtle but can achieve pleasing visual effects Versions: All 68 5 Patrik Beck | General Tips | All Levels Caustics Caustics are caused by refraction in transparent surfaces and reflection, but it is not necessary to activate Trace Reflection or Trace Refraction for there to be caustics Versions: 6. 5 -8 68 6 Patrik Beck | General Tips | All Levels Falloff If the layout of the scene covers a wide... head bone so they follow the character around Versions: 5 -8 312 | Chapter 7 General Tips 68 0 Patrik Beck | General Tips | All Levels Never Use Several Pure White Lights to Light a Scene Changing the color value of the lights in the scene by just a few notches makes it much more natural and pleasing to the eye Versions: All 68 1 Patrik Beck | General Tips | All Levels Using Negative Lights Lights can have...Lighting | 307 General Tips 66 9 Dave Jerrard | General Tips | All Levels Area Lights When using area lights, a quality level of 3 will give you good results and is all you really need, especially if you’re using antialiasing This will save a fair amount of render time with little, if any, reduction in image quality Versions: 6. 5 -8 67 0 Dave Jerrard | General Tips | All Levels Distance from... General Tips 68 8 Lee Stranahan | General Tips | All Levels Use Light Exclusion, Often Often Often Many people don’t take advantage of this hugely useful feature Excluding lights let you handpick which objects are affected by a light and which aren’t This gives you pinpoint control over your lighting setups and allows you to have lights serve very specific purposes in a scene Versions: All 68 9 Lee Stranahan... will do this easily with the click of a button in the G2 preview window However, you can easily do this in LightWave by just turning down the intensity of all other lights or by unchecking Affect Diffuse and Affect Specular in the Light Properties panel Versions: 7 -8 67 6 Rob Powers | General Tips | Intermediate The Size of an Area Light Will Influence How Fast the Scene Will Render You can simply select... Versions: All 69 1 Lee Stranahan | General Tips | All Levels Study Good Lighting for the Result, Not the Technique Lighting in LightWave and lighting in the real world have almost nothing in common Lights in LightWave aren’t realistic at all Things that gaffers and cinematographers and photographers use — like diffusions, spot metering, exposure controls, flags, C stands — have no counterparts in LightWave. .. calculations Versions: 6. 5 -8 69 9 Dave Jerrard | Global Illumination/Radiosity | All Levels Backdrop Only Radiosity For most scenes using Backdrop Only radiosity, you can lower the Rays Per Evaluation to 3 x 9 and get very good results as well as good render times Higher values will increase the render times significantly, while lower values will create very grainy images Versions: 6. 5 -8 700 Dave Jerrard... control, clone the light that is generating the caustics and have it affect only caustics Reposition the light to give it a more desirable caustic angle Versions: All Lighting | 313 General Tips 68 4 Patrik Beck | General Tips | All Levels Faking Radiosity Effects You can fake radiosity effects by using settings in the Light Properties panel Using either point or spot lights, go to areas where there is a... (which also eat a lot more RAM) Lighting | 309 General Tips Here, a shadow map with the size set to 200 looks very chunky and pixelated Here is the same shadow map, but this time the light is spinning on its bank Motion blur smoothes out the errors and creates a better-looking shadow Versions: All 67 3 Rob Powers | General Tips | Intermediate Parenting Tricks When setting up a standard lighting rig such... “shading noise” or speckles in the renders In that case, checking Shading Noise Reduction in the Light Properties Global Illumination panel will help reduce this Versions: 7 -8 Lighting | 311 General Tips 67 7 Rob Powers | General Tips | Intermediate Adjust Shadow Colors When trying to set up realistic lighting, don’t forget to adjust the light’s shadow color in the Light Properties panel to a more appropriate . textures, so you’ll have to test this for each scene. Versions: 6. 5 -8 3 06 | Chapter 7 General Tips 66 9 Dave Jerrard | General Tips | All Levels Area Lights When using area lights, a quality level. nagging requesters! (http://www.kolumbus.fi/erkki.halkka/plugpak/index.html) Versions: 6 -8 66 6 Dave Jerrard | General Tips | All Levels Project a Procedural through a Spotlight You can project a procedural. you’ll have to determine whether to use it on a scene-by-scene basis. Versions: 6. 5 -8 6 68 Dave Jerrard | General Tips | All Levels More on Shading Noise Reduction Shading Noise Reduction can also