Materials processing was further discussed at the Content Creation Informal User Group meeting on September 11th. During the meeting, Oz confirmed that normal and specular maps will have their own rotation and offset controls from the start, which stands in difference to thoughts that they would initially be locked to the same rotation, etc., as the texture map used on an object or object face.

This means that the new materials processing maps will have the same positioning and scaling properties are currently available for texture (diffuse) maps, namely:

• Mapping: one of Default or Planar
• Horizontal  and Vertical Repeats: number of repeats of the image over the surface (used only in default mapping)
• Rotation: degrees clockwise by which the map is rotated
• Repeats per Metre: number of repeats of the image per in-world meter of the surface (used only in planar mapping)
• Horizontal and Vertical Offset: distance in meters the image is shifted right (horizontal) or up (vertical) on the surface.

This obviously increases the amount of control content creators will have over the additional maps once the new capabilities are live, but it does open up more issues around incorporating the capabilities into the build floater. Thus, it was the build floater which once again became the focus of the conversation during the meeting.

How the build tools are presented to users has already been the subject of much broader consideration within the CCIIUG, although that discussion appears to have stalled for the time being. The materials processing process, however, requires a more focused examination of the build floater in terms of enabling the additional controls without either making the existing floater too large or overly complicated.

As such, two ideas were briefly discussed at the meeting, and further input to them both will doubtless be sought. The first involved having the additional options contained within the existing Texture tab as sub-tab options, while the second involved having all of the mapping options (Texture/diffuse, normal and specular) and their associated positioning and sizing options moved to a dedicated floater of their own.

Of the two options, both have merit and pitfalls. Sub-tabs mean keeping everything together on a single floater, but could lead to things becoming cramped or possibly confusing. Splitting between two floaters would provide more space with which to present options and controls, but could lead to a reduced in-world view should people find they need to work with both floaters open.

Given the small number of attendees at the meeting, neither option was discussed in-depth, and so, as mentioned above, this is liable to be a subject which is returned to in future meetings.

Rendering Pipeline Changes

As a part of this project there will be changes to the viewer rendering pipeline. While the project is still some way off in terms of delivery, Oz Linden used the TPV/Dev meeting of September 7th to advise TPV developers that they will need to ensure they are current with the 3.3.4 rendering code, which will form the basis for implementing the materials processing system changes.

Oz also indicated that while it would be “quite a bit of time” before the project reaches a development or beta viewer because the overall specification is not yet frozen (but is, in his words, “Very, very slushy”), it is hoped that a project viewer would soon be available to allow the new materials processing capabilities to be seen and tested.

In referencing the release of a project viewer, Oz advised against anyone trying to pull the code and using it in any viewer intended for wide distribution. This is because it is possible the material processing capabilities may change in very significant ways before they are ready for more general release, leaving the code presented in any project viewer as limited in both value and function.

Accounting System Costs

It is still unclear whether the new materials processing system will fall under the new land accounting system in terms of server and rendering costs. While questions have been asked in this regard, no definitive answers have yet been furnished by LL. This again is potentially due to the matter still being under consideration and the specification itself still being revised as impact and changes are considered.

Discussions on the project will doubtless resume at the next CCIIUG meeting.

Related Links

• Materials Processing articles in this blog
• Content Creation Improvement Informal User Group wiki page

On August 16th, Linden Lab announced the forthcoming arrival of material processing in SL in the form of specular and normal maps. At the same time, a video was released demonstrating some of the capabilities. But what does this actually all mean for the everyday user in SL? Here’s what I hope is a lay guide to things, including comments from one of the architects of the new system, Geenz Spad, as to how it came about.

Materials Processing

This is not intended to be a technical discussion on computer graphics mapping in general or on normal or specular maps in particular. Rather, it is intended to provide a broad, non-technical explanation as to how the latter work. 

Materials processing is the combining of various computer graphics “maps” to significantly increase the level of detail that appears on any object or surface within a computer game. Within Second Life, textures (themselves a form of computer graphics map called a diffuse map) are routinely used to add the illusion of surface details to in-world objects and surfaces. The new material processing capability will introduce two further kinds of computer graphics map to SL which can be used in-world with textures to dramatically increase the detail and realism of objects and surfaces. These additional maps are called normal maps and specular maps.

Normal  Maps in a Nutshell

Normal maps (sometimes referred to as bump maps, although they are more rightly the most common form of bump map) are a means of faking high levels of detail on an otherwise bland surface by means of simulating the bumps and dips that create the detail. Normal maps can be created in several ways.

For example, when working with 3D models, a common method is to make two models of the same object: one a very complex, highly detailed model with a high polygon count, the other a much lower polygon count model with significantly less detail. An overlay process is then used to generate a normal map of the detailed model’s surface features which can be applied to the less complex model, giving it the same appearance as the highly detailed model, but for just a fraction of the polygon count, reducing the amount of intensive processing required to render it.

Another common way to produce a normal map is to generate it directly from a texture file. Most modern 2D and 3D graphics programs provide the means to do this, either directly or through the use of a plug-in (such as the nVidia normal map filter for Photoshop). When combined with diffuse maps, the normal map creates the impression of surface detail far greater than can be achieved through the use of the texture alone.

Specular Maps

In the real world, every highlight we see in an object is actually the reflection of a light source. Surfaces and surface details reflect light differently to one another, depending on a range of factors (material, lighting source point(s),  etc.). Specular maps provide a means of simulating this by allowing individual pixels in an object to have different levels of brightness applied to them, giving the illusion of different levels of light being reflected by different points on the object.

Like normal maps, specular maps can be produced in a number of ways, both within 3D graphics modelling programs and in tools like PhotoShop. As shown above, they can be combined with normal maps and textures to add detail and realism to 3D models and flat surfaces.

What Does This Mean for Second Life?

Second Life itself already includes a dynamic example of how normal and specular maps can be used: Linden Water. This is created using an animated normal map to create the wave-like effect for the water, while an animated specular map adds the highlights and reflections. The result is a very realistic simulation of moving water able to catch and reflect sunlight.

Just as the use of normal and specular maps create a very real illusion of water with Linden Water, the new materials processing capabilities will significantly enhance the look and realism of both mesh and prim content within SL. Mesh content should additionally benefit as it will be possible to produce high levels of detail on models with low polygon counts (as shown in first image in this article). This will improve rendering performance while also having the potential to lower things like land impact for in-world mesh items.

The only initial limitations as to where and how normal and specular maps can be applied is that they will not be applicable to avatar skins and system layer clothing. Any decision on whether the material processing capability should be extended to include these will depend upon at least two things:

• Community feedback – whether there is a demand for normal and specular maps to be used with avatar skins
• Understanding what is happening with the avatar baking process, and determining what is involved in getting the new baking process and material processing to work together.

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