GRIME MANUAL: GRIME-NURBS

Grime-Nurbs applies dirt by examining the geometry of whole objects and looking for concave parts. It is perfect of applying dirt to complicated objects made up of a large number of small polygons (like the Beethoven bust in the tutorial section).

Gradient

Grime has a gradient feature which gives the user perfect control over the amount and location of dirt. Its spectrum has an unlimited number of values, which makes this feature a very flexible tool.

Fractal Noise

For the dirt to look even more realistic Grime has a fractal noise feature which prevents too uniform application of dirt. It also makes it possible to create damp patches caused by leakage and other special kinds of dirt.

All Channels

With Grime the dirt effect can be applied to all surface channels (color, specularity, luminosity, reflectivity and transparency). Thus dirty parts of glossy objects can be made less glossy, dirty windowpanes less transparent, etc.

Now your objects will no longer look brand new, unless you want them to, instead, they will have a much more interesting real-life look.

GRAPHIC USER INTERFACE

The GUI is divided into three sections: the general options, Set tabs and Surface Channels Tabs.

Max Dust Size

This option determines sample size, i.e. the width of cracks to be grimed. The default setting is 1.0.

Examples

Here sample size is 1, which means that all cracks of up to 1 meter in the width will be grimed.

figure 1a - click to enlarge

figure 1b

Using the gradient option users can adjust the intensity of dirt application.

figure 2a - click to enlarge

figure 2b

For figure 3 the sample size is 0.2, which means that all cracks of up to 20 centimeters in the width will be grimed.

figure 3a - click image to enlarge

figure 3b

Using the gradient option users can adjust the intensity of dirt application as displayed in figure 4.

figure 4a - click image to enlarge

figure 4b

Nurbs smoothing

This option smoothes the dirt effect. The default setting is ON.

Use existing geometry files

While processing a given object for the first time Grime creates .grm files which contain object geometry data. During subsequent renderings Grime uses those files for faster rendering, unless the Max dust size setting or object geometry have been modified. The default setting is ON.

Create missing geometry files

If there are no .grm files available, this option creates them. The default setting is ON.

In this section the dirt fractal properties are determined. The four sets enable users to apply different fractals to different surface channels. This is done by clicking on the Set pull-down menu in the Surface channels section and selecting the set for the active channel tab.

Below are sample combinations of the Peak pos, Zero scale, Peak pos and Max scale parameters settings:

Examples

The following settings apply a uniform dirt layer without any fractal noise. See the highlighted pull-down menu with the None setting selected.

figure 5a - click image to enlarge

figure 5b

In figure 6 Set 1 has been applied. This is the default fractal noise setting.

figure 6a - click image to enlarge

figure 6b

Since users may not want fractal noise to cover the entire surface, the parameters can be specified to limit the fractal application area. In the following combination the ‘crack’ is evenly filled and the fractal is applied to the ‘non-crack’ surface.

figure 7a - click image to enlarge

figure 7b

This time fractal noise is applied to the ‘crack’ only.

figure 8a - click image to enlarge

figure 8b

The settings for figure 9 limit the amount of fractal noise on the crack edge.

figure 9a - click image to enlarge

figure 9b

Here fractal noise has been applied solely to the crack area.

figure 10a - click image to enlarge

figure 10b - Compare this with figure 6 .

Figure 11 has almost the same settings as figure 9 (click back to return here), but the deepest area of crack is filled evenly. Note also how the gradient settings were modified to produce this effect (as highlighted).

figure 11a - click image to enlarge

figure 11b - Compare this with figure 8 (click back to return here)

Continuous random pull-down menu

With the default setting, i.e. Continuous random, Grime applies random values selected from the entire spectrum, to all 3D points. Other settings include 2 values, 3 values, 5 values and 10 values. By selecting one of them users can determine from how many values of the spectrum Grime will choose at random the value for a given point.

2 bits pull-down menu

This option determines fractal depth. Other values include off, 1 bit, 3 bits, 4 bits, 5 bits, 6 bits, 7 bits and 8 bits.

Size

This option determines fractal size. The default setting is 0.1m.

Seed

This options generates random fractal seeds.

Effect

This gradient applies the color / luminosity / diffuse / specularity / transparency / reflectivity effect to concave parts of objects. By clicking on the gradient spectrum users can select keyed values of the gradient and then precisely adjust the positions of values using the numeric box with arrows and Add and Del buttons below.

Flip button and Copy / Paste buttons

For easy editing Grime’s GUI has Copy / Paste buttons and a Flip button. The copy / paste options allow users to copy settings of one surface channel into another surface channel (in LW 5.6 it is also possible to copy settings from one Grime into another if two or more have been opened). The Flip button reverts the gradient spectrum.

Set 1 pull-down menu

This option applies a fractal (set in the Set Tabs Section) to the active surface channel. Four different fractal settings are available.

Opacity

This gradient determines the opacity of the color / luminosity / diffuse / specularity / transparency / reflectivity effect. By clicking on the gradient spectrum users can select keyed values of the gradient and then precisely adjust the positions of values using the numeric box with arrows and Add and Del buttons below.

Flip button and Copy / Paste buttons

The copy / paste options allows users to copy settings of one surface channel opacity into another surface channel (in LW 5.6 it is also possible to copy opacity settings from one Grime into another if two or more have been opened). The Flip button reverts the opacity gradient spectrum.

Set 1 pull-down menu

This option applies a fractal (set in the Set Tabs Section) to the active surface channel. Four different fractal settings are available.