Integrated mental ray 3.6 Renderer - XSI 7.0 integrates the award-winning mental ray renderer, now at version 3.6. This update adds new controls for final gathering and displacement rendering, as well as options for optimizing and accelerating global illumination, and global ambient occlusion settings.

Rendering features added:

• Importons - Importons are photon particles emitted from the camera (instead of a light source). mental ray uses these photon particles to calculate how important a photon is for the illumination of an image. With this technique, you get a lighter photon map and faster rendering as photon lookup is optimized.
• Stand-ins - Object render archives (also known as mental ray assemblies or stand-ins) provide a method of offloading assets so that they can be loaded and unloaded, on-demand, at render time. The object render archive file is loaded into the render as an encapsulated "sub-scene" which can be unloaded automatically if mental ray starts to run low on physical memory. This reduces memory consumption and allows for faster rendering times. Stand-ins are particularly useful for assembling cumulatively large and detailed scenes such as cityscapes, dense forests of trees, and even crowds of animated characters.

• New Final Gathering Algorithm "Exact" mode - Exact mode bypasses the final gathering point cache entirely and always computes the full final gathering solution for every sample. This mode will yield more accurate and superior quality results because none of the final gathering points are derived by interpolating values from an initial cache of final gathering points.
• Auto-Configuring BSP 2 Raytracing Acceleration - The BSP2 raytracing acceleration technique is the next generation BSP algorithm used by mental ray. It was developed, primarily, for the efficient rendering of scenes with large BSP trees and is required for rendering scenes with stand-ins (also known as mental ray assemblies). It is also auto-configuring so the user does not have to setup complicated BSP options anymore.
• Irradiance Particles - The new mental ray irradiance particles algorithm provides a method of calculating global illumination using importons.

Render Manager Improvements - The render manager provides a convenient view of all the important rendering options that will help you fine-tune and output your scene. These options apply to the entire scene, each render pass you define, and the renderer itself. For XSI 7.0, the render manager’s user interface and workflows have been simplified.

XSI version 7.0 supports the Realtime Shader API version 3.0. There have been some major changes and enhancements since version 2.0 that add flexibility and simplicity in the development of realtime shaders:

• The new architecture focuses on programmable shaders (GLSL, HLSL) and file-based effects (CgFX and DxFX).
• Geometry is now passed to realtime shaders as multiple fixed-size, flat arrays of floating points. Prior to v3.0, fixed vertex structures were sent to the renderer, but now each realtime shader requests a list of attributes it needs to render the geometry.
• For polygon meshes and NURBS, topology is defined as a list of indexed triangles.
• Particle clouds are fully supported, passed as arrays of points.
• New ExecutionState object encapsulates all calls made to the graphic subsystem and scene accessors.

GLSL Shaders

XSI provides two new OpenGL-based realtime programmable shaders that support the OpenGL Shading Language (GLSL): the GLSLProgram shader and the GLSLUniform shader.

The OGLParticle shader is a realtime shader that allows you to shade your particles in an XSI 3D view set to the OpenGL display mode.

Text Editor Widget

XSI now provides a new, customizable Scintilla-based editing component which supports text customization (font, color, size), syntax styling, folding (hiding blocks such as functions and subroutines), auto-completion and highlighting for keywords. The text editor widget is implemented as a control on the property pages of all the programmable realtime shaders.

Vertex Shader Input Semantics

When an effects file (.cgfx and .fx) is compiled, any vertex shader variables bound to input semantics will dynamically generate a user interface. You can use the vertex attribute widgets that get generated to customize the per-vertex attributes that are passed to the effect.

ICE user interface on Render Tree - The Render Tree uses the ICE interface meaning that you enjoy the benefits of ICE including:

• Shader Compounds - A Compound is a collection of nodes grouped together into one node with inputs and outputs. You can open up a compound and edit nodes anytime. You can also create compounds of compounds (of more compounds - it's infinitely abstractable). Using the Render Tree, shader trees can get quite large quickly. Creating compounds not only makes your shader tree easier to manage, but also lets you re-use and share the compounds easily.
• Navigate large render trees easily with the ICE tree navigator.

Zoom with the mouse wheel - By default, you can zoom using the mouse wheel. Scroll forward to zoom in and backward to zoom out. Press Ctrl to zoom quickly, Shift to zoom slowly, and Ctrl+Shift to zoom even more slowly. This works in viewports, ICE trees, Schematic View, Animation Editor and other areas of the software.

Automatic Scaling on Sliders - When you set a value outside a slider range, for example by typing it in, the displayed range automatically expands to twice the current value. For example, if the default range of a parameter is between 0 and 10 and you set the value to 15, the new range is 0 to 30. The change is not permanent — if you set the parameter to a value within the default range and then close and reopen the property editor, the displayed range is back to its default.

Delta II Referencing

One of the major breakthroughs in workgroup collaboration was Delta referencing (in XSI 6). In addition to XSI's robust referencing system, Delta allows you to store the changes to a model in a lightweight manner. You can then export, import and apply deltas manually. You can also edit and delete deltas and items within deltas, and even change a delta’s target model. The result is an extremely efficient, robust and flexible way for artists to work collaboratively in production.

Delta II updates the already successful referencing system with numerous new features:

• Create New Clusters
• Create new cluster properties, including texture UV coordinates, vertex colors, weight maps, and envelope weight properties. You can create cluster properties on new clusters, or on clusters that pre-existed in the original model.
• Add deformation operators and ICE trees to the construction stack. This includes deformations on new and pre-existing clusters as well as deformations that are linked to other objects (lattices, waves, cluster centers, etc.).
• Add operators to the stacks of cluster properties, including painting and smoothing weight maps and envelope weights, modifying texture UV coordinates, etc. Note that UV modifications are frozen when the model is offloaded (including before switching resolutions or saving the scene).
• Delete any operators, clusters, properties, and cluster properties that have been added to the referenced model. Deleted items are removed from the delta.
• Save animation mixer Cache data in the delta.

Texturing and Maps

Editing Multiple Texture UV Sets - You can now display and edit multiple UV coordinate sets simultaneously in the texture editor. These UV coordinate sets can belong to a single object, or, if more than one object is selected, to multiple objects.

This is useful for a number of tasks including:

• Positioning one object’s UV coordinates relative to those of another object on the same texture image.
• Positioning multiple UV coordinate sets belonging to a single object on the same texture image.
• Making sure that geometrically identical objects’ UV coordinates are unfolded the same way.
• Creating a single set of rendermap images for multiple objects.

Any UV coordinate set that is currently displayed in the texture editor is “live” and can be edited. You can select and modify sample points on multiple coordinate sets simultaneously. You can snap sample points from one set to another, and copy and paste coordinates between sets. The different coordinate sets are independent for the purposes of operations like healing, relaxing, and matching.

Color Management

XSI 7 gives you global controls for working in linear color space and managing Gamma correction so what you see in XSI is what you get outside XSI. You can define gamma correction using RGB values or a lookup table, and specify which XSI views display your gamma correction.

You can toggle Gamma correction display for textures, render regions, preview renders, shaderballs, the XSI Illusion compositor, and most XSI color controls. Now you can easily render in linear color space while outputting Gamma-corrected display settings for monitors. You can even use the render region’s compare tool to compare renders before and after Gamma correction.

Global Gamma Correction Display Preferences

You can define a gamma correction display preference that stores a global lookup table built from values specified in a LUT file or from RGB gamma values that you set on the Color Management tab of the Display Preferences property editor.

Gamma Correcting a Render Pass

You can render out gamma-corrected images for a pass by enabling the Apply Display Gamma Correction checkbox in the Render Pass Property Editor for that pass. The render pass is output using the gamma values set in the global gamma correction display preference. The images’ pixels are modified accordingly on output.

Gamma, Color Profiles and Image Clips

XSI converts all image clips into linear floating point data. To accurately convert and render out each image clip, you can select the color space in which your original image was created. This indicates to mental ray how to convert (if necessary) the image clip from its current color space to the linear floating point color space, including whether or not any gamma correction data is stored.