Rock Shader for DAZ Studio

Contents

Large 3d boulders in a grassy field. Introduction Important Concepts Quick Start Quick Tips Parameter Settings Known Issues

Introduction

Seabirds resting on a small rock island in the ocean.

The AoA Rock Shader turns almost any DAZ Studio object into a detailed, procedural, rock surface.

All aspects of the shader are procedural and do not rely on UV mapping. This allows every aspect of the look to be tuned. Additionally, the effect will render completely seamless even on objects without UV coordinates.

To give an idea of how well the shader does at randomizing shape, every one of the rocks shown in this user guide is simply a DS, 6 polygon, cube primitive with SubD applied!


Important Concepts

A subdivided cube instanced 5 times to create random boulders.

Although the AoA Rock shader can be used on any object, the intent is mostly aimed at creating natural rocks and boulders rather than use with carved stone surfaces like statues.

The shader uses an object's location in the scene as a seed for randomization of the surface. Because of this each object will have different bumps and features even on objects which are exact copies of eachother.

Complex boulders can be easily made even from the simplest geometry such as a SubD cube. This, used with DAZ Studio's instancing feature, allows the creation of highly complex looking scenes, such as piles of rocks or an asteroid field, with as few as 6 polygons.

Because of the shader's use of world coordinates to drive randomization, the Rock shader may not be suitable for use in animations where the rock itself is moving. Camera movement or animation of figures around the rocks should work fine though.


Quick Start

Applying the AoA Rock shader onto an object in the scene.

The base rock shader can be found in the content tab under Shader Presets - Age of Armour - Rock.

Additional presets, created by Dimension Theory, are located in the DT-Presets sub-folder.

To apply the rock shader, select an object and its material zones then double click !Rock Shader Base or one of the included rock presets.


Quick Tips

Example of 3 rocks with all the same settings except positive and negative displacement reversed.

General

Parameter Settings

Advanced Light Flags Group

The parameters of the Advanced Light Flags group contain settings for use with the AoA Advanced Lights.

The settings themselves do nothing to the appearance of the rock. They simply provide parameters which can be used for flagging when used along with the Advanced Ambient, Distant and Spot lights.

See the AoA Advanced Lights user guides for more information on flagging.

Bumps Group

A comparative chart of renders illustrating the effect of the AoA Rock Shader's bump density setting.

The Bump settings of the rock shader create fine surface detail rather than the large, feature changing settings of the Shape Group settings.

Despite their names, the bump settings do, in fact, create displaced geometry. As such, they are affected by the Displacement settings and the size of an object.

Adjustment of the Bump Strength setting is commonly required when using the shader on small objects or when using high Minimum Displacement or Maximum displacement values.

Diffuse Group

The effects of the Speckle Density setting of the AoA Rock Shader.

The parameters in the Diffuse group set the base colors of the stone. There are two main colors that are further mixed with speckles, spots and the additional settings in the Veins Group. Together, all these settings can create quite a lot of color variation yielding extremely detailed and believable rock surfaces.

Displacement Group

In the rendering process 3delight converts all 3d models of the scene into micro-polygons. These micro-polygons can then be moved, via displacement, to change the shape of the 3d models.

The shape settings of the shader generate the math for changes to the rock shape but it is displacement which actually does the work of moving the micro polygons into place.

The internal shape calculations result in thousands of number values between 0 and 1. When displacement receives a number between 0.5 and 1 it moves the surface of the rock outward. In areas where displacement receives a shape value of 0 to 0.5 it pushes the micro-polygons inward.

The Minimum Displacement and Maximum Displacement settings are in centimeters. So if the Shape functions result in a value of 1 for a spot on a model and Maximum Displacement is set to 10, then that point on the surface will move outward 10 centimeters.

You should choose Minimum and Maximum values which are appropriate to the object. If you have a giant, building sized boulder then values of Min -100 and Max 100 might look good. But if you were to use that on a small rock the size of your fist then having cracks 100cm deep would not look good.

When the Minimum and Maximum displacement settings are opposite each other (Such as 10 and -10) then the model should deform but still remain approximately the same size overall. However, the Shape settings generate such highly randomized values, there is no real way to predict if a rock will be in an area where displacement is receiving more low numbers than high numbers.

Because of this you may need to shift one of the values to compensate. If the overall size your rock is shrinking too much you can increase either, or both of the Min and Max displacement values. So instead of Max 10, Min -10, you might try Max 15, Min -5 to increase the overall size of the object.

Moss Group

AoA Rock Shader's Moss Spread Angle function.

This feature generates moss in shadowed areas of the rock. Though its placement is not exactly how moss grows in real life, it can be a nice addition to help give some extra, subtle believability to a forest scene.

The Moss uses a ray tracing function to detect what areas of the rock are shadowed, being close to the ground or near other objects. This requires a Max Ray Trace Depth of at least 1 (In the DS render settings) to function. Although the Moss feature uses ray-tracing, it actually renders quite quickly.

Shape Group

A comparative chart illustrating the Feature Complexity parameter of the the AoA Rock Shader.

While there are only 3 settings in the Feature group, they are very powerful to create complex, stone-like randomizations to an object's shape.

These functions calculate surface changes which are then multiplied by the Displacement settings. If your rock features are too strong or not strong enough, try adjusting the values in the Displacement group.

A comparative chart illustrating the Feature Density setting of the the AoA Rock Shader.

Smoothing Group

The two settings of the Smoothing group determine if edges between polygons are to be creased or rounded based on angle.

At this time neither of these settings have any effect on subdivided geometry.

Specular Group

As with other DAZ Studio shaders, specular highlights can help give surfaces a glossy look by simulating the reflections of bright light sources.

UV Maps Group

Because the Rock shader does not require UV coordinates, this setting has no practical use unless a different shader, which makes use of UVs, is applied to a geometry shell of the object.

Veins Group

A comparative chart illustrating the Vein Strength setting of the the AoA Rock Shader.

Veins give the ability to create the look of marble or granite with rippled streaks of a different color material going through the rock.

Many of the vein parameters are reliant on other vein values. For instance, the Vein Perturbation function will have no effect, even at 100% strength, unless the Vein Undulation setting is greater than 0 and vise versa.

Admittedly, some of the Vein parameters are a bit confusing and unintuitive. Please accept my apologies for not thinking of more meaningful labels and more logical methods for these functions.


Known Issues

Only when very soft shadows are used - A strange issue was recently reported by Dimension Theory who noticed that shadows cast by heavily displaced geometry could suddenly become inaccurate at some high shadow softness settings. The cause and how long the bug has been there is unknown but was discovered in DAZ Studio 4.6.0.18.

The bug happens when using any directional light along with any surface shader with displacement, including the DS Default lights and shaders. As such, it does not appear to be a bug in this particular shader but I thought it worth mentioning since the AoA Rock Shader does use quite high displacement, increasing the likelihood the issue will be noticed.


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