Essential Blender- P23 ppsx

Figure LT.29: amb occ render with default settings. A render lit only with Ambient Occlusion. Raising the Samples value for Ambient Occlusion smoothes out the graininess, but, of course, takes longer. It's quite common to work on a scene that will include Ambient Occlusion with a very low sample value, like 2, to enhance speed for[KM] while you get things as you want themtweak the rest of the scene. After that, you can turn it up to 10 or so for your final render and get yourself a cup of coffee. To demonstrate how believability in an image can be significantly enhanced by using Ambient Occlusion (often usually referred to as "AO"), let's bring back our Area lamp. Enable Layer 3 (by Shift-LMB on the Layer 3 button on the 3D header, or by using Shift-3), and render). Since the AO is already adding a significant amount of light to the scene, turn the Area lamp's Energy slider even further down to 0.1. Render. The result is a softly lit scene with a high degree of believability. If you would like to really remove the grain in the render, change the AO samples to 10 and check the new result. AO samples can be set as high as 16, but excellent results are usually achievable without going that far. Figure LT.30: final render. The final render. Conclusion Lighting is an art form in itself. Large CG companies have artists on staff who do nothing but lighting. It is a complex topic , one that can make or break a scene. While we've shown you the mechanics of using Blender's lighting tools in this tutorial, we encourage you to work through the discussion section of this chapter, and to seek out other resources to enhance your artistic abilities. Chapter 12: Particle Toolset Discussion By Roland Hess Particle systems are different from other Blender objects in a number of ways. First, instead of being made of faces, edges and vertices, they are composed of a large number of points (up to 100,000). Second, the locations of these points are calculated by Blender and are based on velocity and force values, instead of being modeled by the user into exact shapes. Figure pd.01: Various particle systems, both rendered and in the GUI. Particle systems can be used for a variety of effects, but are most commonly found when making "aerial" effects like smoke, fire, clouds, dust motes floating in sunlight, magical sparkles swarming around an actor you get the idea. Emitters Particle systems need a place to start. That place is an "emitter." In Blender, an emitter can be any mesh object you choose. The shape of the mesh will form the starting point for the particles. A particle system is created by RMB selecting a mesh object, and clicking the "New" button in the Particles panel of the Object buttons (F7), found in the Physics buttons subcontext. Tip: Particles systems are generated by emitter objects. Figure pd.02: The Particles panel. In the default configuration, the Particle Motion panel is nested as a tab behind the main Particles panel, but we've pulled it out to show you everything at once. Before you examine the particle tools, a couple of points about particle systems in general are in order: - There are two kinds of particle systems, Static and Dynamic, each of which has its own tutorial. Static particles are used for systems of Strands like hair, fur and grass. Dynamic particles are used for the previously mentioned fire, smoke and dust effects. - Unless you take special steps, the emitter mesh itself will not show up in a render. The most basic settings for particles are found in the "Emit" section of the panel. Amount: This is the total amount of particles in the system. How many you use will vary in relation to exactly what you are trying to do. Keep in mind that more particles will take more calculation time, and, depending on the speed of your computer, may slow things down significantly. Sta: This stands for start, and refers to the frame number on which the emitter will begin to create particles. End: The last frame on which the emitter will create particles. An emitter will create particles at a constant rate between the Start and End frames. So, with only these three controls, you can cause some serious differences in the way particle systems can act. 10,000 particles being created between frames 1 and 1,000 will make 10 particles per frame, a fairly low rate. On the other hand, 10,000 particles with a Start of 1 and an End of 2 will cause a burst of all 10,000 particles within 1 frame. Think of a fireworks explosion. Life: How long each particle will live. Particles hang around in the scene for only as long as this parameter will let them. After they die, new particles will be emitted to take their place, up until the End frame is reached. A low Life value (a couple of frames) will have particles blipping into and out of existence rapidly, like short-lived sparks thrown from a welding torch. Life settings that are longer than the amount of time the particles are actually being emitted will cause a build-up effect, with all emitted particles hanging around in the scene long after the End frame. Disp: Percentage of particles to display. This is indispensable when you are working with particle systems that have enough particles to slow down your Blender experience. The value here is a simple percentage: 10 shows only 10% of the total particles, 50 shows 50%, etc. The really nice thing is that it is not just a display speedup. Until render time, Blender does all of its particle calculations on this reduced amount, giving good speed boosts for any particle-related activities. When you render your scene, though, the full particle amount is used. You can also control which parts of the mesh emitter the particles come from, in the appropriately named "From:" section of the panel. By default, both the "Verts" and "Faces" buttons are On, meaning that particles can be emitted from either vertices or faces. For certain effects, you could restrict it to one or the other by setting either to Off. For example, if you wanted to create an effect where particles emitted in a burst from several points on a grid, you would turn off the Face option. Figure pd.03: The particle system on the right shows particles emitting from faces and vertices. The one on the left only emits from the vertices. Rand: Creates a truly Random distribution. The normal distribution of particles looks pretty random to the untrained eye, but from a mathematical perspective it isn't. Without getting all math-geeky, really random things tend to cluster and clump. Their elements are not as orderly as the standard particle layout. When looking at the illustration, you can see patterns in the standard emit, but none in the Random emit. Figure pd.04: The particle system on the left has the normal particle distribution. The one on the right is using the Rand option. Even: Attempts to distribute particles evenly over the surface of the mesh emitter. Usually, Blender assigns particles on a per-face basis, meaning that in a 20,000 particle system, each face of a 100 face mesh gets to emit 200 particles. That sounds fine until you realize that some areas of the emitter mesh might have more densely packed, smaller faces. Particles will be denser in those areas. Using the Even option attempts to alleviate this by assigning each face a number of particles in proportion to its part of the area of the mesh. You need to be careful when using this option with things that could change the shape of the mesh though: shape keys, character animation through armatures, lattices, etc. These tools can change the relative sizes of faces in your mesh, causing particles to seem to jump around as they are reapportioned for different face areas. Vgroup: Vertex Group. Vertex groups are covered in Chapter 4. You can enter the name of an already-created vertex group here to cause only that portion of the mesh to act as an emitter. Figure pd.05: A mesh with a vertex group of a face saved. The particles are set to emit from the "face" vertex group. Materials: What do the particles look like? Particles use a material option that is not covered in the Materials and Texturing chapter. We'll go over it here. To get the most out of this, you should probably have read Chapter 9 so you understand the basics of creating and working with materials and textures. By default, particles are rendered with the Halo material. Halos are rendered at a different stage than normal geometry, and are strictly 2D effects placed into the final render. Note: Halos do not react to raytracing, so they will not show up in Ray reflections or Ray transparency. Also, as they are a 2D post-render effect, Halos cannot cast shadows. The following illustration shows what halos can look like: Figure PD.24,25,26: A particle system, showing two different Halo settings. A material's halo options can be accessed by enabling the "Halo" button on the material's Links and Pipeline panel. Figure PD.22: The Halo options for materials. Tuning Halos to get them to do what you want is not an exact science. A lot of trial and error will be involved, so try not to become frustrated. HaloSize: This controls the overall size of the Halo. When working with Halos, this is the first setting to start playing with. Hard: This control varies Halos from rendering as tiny dots with a small lightness surrounding them (1.0) to diffuse circular blobs with no discernible center (0.0). Particles that should look like "magic" would have high Hard values, where smokes and other less defined effects would require near-zero values. Add: Determines the level to which Halo effects reinforce themselves. Normally, several halos stacked in front of each other would only render the values for the nearest halo. With Add turned up to 1.0, stacked Halos reinforce each other, accumulating their brightness. Particle systems that are meant to simulate fire should have high Add values. In addition to the "glowing ball" look, Halos can be given other properties, too. Figure PD.23: Ring, Lines, Star, and all three together as Halos. The particle systems in the illustration show the effects of the Ring, Lines and Star buttons on the Shaders tab. The buttons can be combined, as seen in the system on the lower right. The numbers of Lines and Rings are controlled by the corresponding spinners on the same panel. Line and Ring color can be adjusted individually through the color pickers on the Material panel, where the Spec and Mirror colors normally reside. Shading By enabling the "Shaded" button on the Shaders panel, you can make Halos react to light. [...]... adds a bit of random motion on top of that generated by the other controls Usually, very low values (0.001-0.025) will add believability to certain effects However, this control can easily override and essentially destroy other carefully refined control values, especially if it is cranked the whole way up to 1.0 Try it and see Damping: Damping is a sort of friction control 0.0 damping means that particles . (0.001-0.025) will add believability to certain effects. However, this control can easily override and essentially destroy other carefully refined control values, especially if it is cranked the whole