Krakatoa MX: Rendering
This chapter discusses the various rendering and shading modes of Krakatoa and their use with particles from different sources.
This topics will introduce you to the basic principles of volumetric particle rendering.
This topic discusses the behavior of particle density when rendering in Krakatoa and the available controls to tweak the final result.
This topic discusses the best practices for rendering massive particle clouds without producing grainy output.
The Voxel Rendering mode of Krakatoa lets you render denser-looking volumetric clouds while typically using less particles to achieve the same result as in Particle Rendering mode. Particles are registered on a grid of box-shaped spatial "cells" which are then shaded to produce a continuous volume without the gaps usually produced when approaching or flying through a particle cloud in Particle Rendering mode. In addition, Krakatoa shades the voxel grid one slice plane at a time, resulting in orders of magnitude lower memory consumption compared to the Volumetrics system of 3ds Max.
This topic discusses the volumetric shading in Krakatoa and the four main shading channels (Scatter Color, Emission, Absorption and Density) used in the volumetric rendering process.
This topic discusses the Krakatoa Shaders (also known as Phase Functions) which determine the behavior of light rays as they interact with particle clouds. The current list of Shaders includes Isotropic, Phong Surface, Henyey-Greenstein and Schlick.
Since Krakatoa v1.5.0, Volumetric and Additive shading can be performed within the same rendering and are controllable per-particle via the Color, Emission and Absorption channels. This topic demonstrates how to achieve a mixture of Additive and Volumetric particles in the same particle cloud.
Krakatoa v1.5.0 and higher allows the rendering of an Environment Reflection Map pass (using the Environment Map slot of 3ds Max and the particle Normals channel) as an extra view-dependent lighting pass. This topic discusses the use of Environment Reflections and the available controls over their look.
Krakatoa MX v2.0.0 introduces the ability to show Matte Objects and Atmospheric effects on particles using a special Raytracing mode available through the Krakatoa Material's Emission channel.
Krakatoa MX v2.0.0 and higher allows the rendering of the 3ds Max Environment Map as a background of the particle rendering, enabling the quick compositing of particle renders with existing images without the use of image post-processing.
This topic discusses the use of the native Krakatoa Motion Blur and the 3ds Max MultiPass Motion Blur Camera Effect.
This topic discusses the use of the native Krakatoa Depth Of Field and the 3ds Max MultiPass Depth Of Field Effect.
Normally, Krakatoa attenuates light as it passes through particle clouds, but in some cases, it is useful to be able to attenuate light as it passes through the ambient medium that contains the particles without representing this medium as particles for performance reasons. For example, if the particles to be rendered represent silt particles in a water medium or dust particles in air medium, the Ambient Participating Medium Extinction can simulate the effect the water or air would have on light passing through it. This topic discusses the usage of the APME sub-system to achieve this effect.
Integration With Other Renderers
Krakatoa MX 2.0 introduced a ray-marcher that could render within other renderers that support the native 3ds Max Atmospherics sub-system like Default Scanline, V-Ray, finalRender and Brazil r/s. This effect allows the integration of voxel rendering including shadow casting from and onto the volume and interaction with raytraced reflections and refractions.
Krakatoa uses Matte Objects to prevent particles hidden behind scene geometry from rendering and to calculate shadow casting from scene geometry onto particles. Since version 1.5.0, Krakatoa uses fast scanline techniques in place of the previously available raytracer. This topic describes the features of this new matte objects renderer including support for opacity-mapped matte objects.
In versions prior to v1.6.0, Krakatoa used Light Projection Maps to emulate shadow casting from particles onto geometry objects. The Krakatoa Shadow Generator implements a 3ds Max shadow generator that can save Deep Opacity Maps describing the light attenuation from particles within the light's cone and combine this information with regular 3ds Max shadow generators to produce complete shadows in the Scanline Renderer and compatible renderers like VRay. This topic discusses the use of the Krakatoa Shadow Generator.
Krakatoa v1.6.0 added support for dedicated Render Element types which can be used to generate various Renderer, Shader and Particle Channels Data elements to be used in 2D compositing workflows.
Iterative and Interactive Rendering Techniques
This topic describes the ability of the Iterative Mode feature to produce reduced or enlarged versions of the final output while preserving apparent density for faster tests using fractions of the particle count.
Krakatoa provides a Particle Cache which stores in memory all particle channels used by the Renderer except for the Lighting channel, and a Lighting Cache which can also lock the Lighting in memory. When these options are enabled, Krakatoa can render the particles very fast multiple times without the overhead of reloading all particles, reevaluating their modifier stacks and materials and recalculating the Attenuation from all scene lights. This topic discusses the use of these particle caches and their benefits and limitations.
Lighting and Relighting
This topic provides some ideas about using the ability of Krakatoa to save the Lighting data into the Emission channel for relighting in post