Difference between revisions of "Default Shader 4.5"

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m (Added more example images to Displacement tab for Displacement image, Displacement modifier, and Displacement function settings.)
(Roughness Tab)
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== Roughness Tab ==
 
== Roughness Tab ==
 
[[File:DefShdr_02_GUI_RoughnessTab.png|none|470px|Roughness Tab]]
 
[[File:DefShdr_02_GUI_RoughnessTab.png|none|470px|Roughness Tab]]
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Settings on this tab control the smoothness of a surface material. All the settings are multiplied together and evaluated to determine the final roughness value. When the combined values evaluate to 0 a perfectly smooth surface will result and reflections will be sharp and mirror-like.  Rougher surfaces are the result of values closer to 1.0 and will make reflections appear more blurry.
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<br />
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'''Settings: '''
 
'''Settings: '''
 
<ul>
 
<ul>
* '''Roughness: '''
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* '''Roughness: '''This value should be set to 0 for perfectly smooth surface materials and up to 1.0 for rougher surfaces.
* '''Roughness image: '''
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* '''Roughness image: '''This setting allows you to specify an image file to use for roughness.
* '''Invert image: '''
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* '''Invert image: '''When enabled, or checked, the image assigned to the “Roughness image” is inverted, i.e. black becomes white.
* '''Gamma image:'''
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* '''Gamma image:'''When enabled, or checked, assumes the image assigned to the “Roughness image” is in sRGB colour space and needs to be converted to linear colour space.
* '''Roughness function: '''
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* '''Roughness function: '''This setting allows you to assign shader or function nodes to determine the surface material’s roughness value.
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<ul> [[File:DefShdr_27_RoughnessTab_Roughness0-1_Metalness1.jpg|none|800px|Roughess settings 0 - 1]] </ul>
 
</ul>
 
</ul>
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<br  />
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== Specular Tab ==
 
== Specular Tab ==
 
[[File:DefShdr_03_GUI_SpecularTab.png|none|470px|Specular Tab]]
 
[[File:DefShdr_03_GUI_SpecularTab.png|none|470px|Specular Tab]]

Revision as of 20:20, 25 November 2020

Default Shader GUI


Overview[edit]

The Default shader node forms the basis for object surface mapping. It can provide base colours or load external images, as well as allowing control over translucency, luminosity, specular effects, displacement and opacity. Beginning with Terragen 4.5 the Default shader has been improved for working with Physically Based Rendering (PBR) materials.

Many aspects of this node are made up of groups of related settings. For example the base colour aspect has settings for "Base colour", "Colour image" and "Colour function". All of these settings work together to control the particular aspect they relate to.

This has implications you might not expect. For example, lets say you want to map the image of a leaf onto the leaf polygons of a plant model. For the true colours of the image to come through you need to set the "Base colour" to white. If it was set to some other colour, like red, that colour would influence the colours from the leaf image, tinting them red. You can use this to your advantage. If you thought the image was too bright you could use a grey colour to make it darker.

Keep in mind that the different settings of each group aspect interact with each other. This makes the Default shader very versatile, but you might want to make step-by-step changes and render previews in order to see their effect as you learn how they work together.

Here are some tips to working with the different aspects of the Default shader:

To specify a basic colour:

  • Choose a colour with the "Base colour" setting.
  • Don't specify anything for the Image and Function settings.

To use the colours directly from an image:

  • Choose an image file with the "Colour image" setting.
  • Set the "Base colour" setting to white.
  • Don't specify anything for the "Colour function" setting.

To use the colours directly from a shader or function:

  • Assign a shader or function to the "Colour function" setting.
  • Set the "Base colour" setting to white.
  • Don't specify anything for the "Colour image" setting.

To use an image or function to control where the colour appears:

  • Specify the colour using the "Base colour" setting.
  • Specify a greyscale image in the "Colour image" setting or "Colour function". More of the specified colour will appear where the image or function is lighter. White means full colour and black means no colour.

Colour Tab[edit]

Colour Tab

Settings:

    • Base colour: This setting specifies the basic colour of a surface material, and acts as a multiplier to the "Colour image" and "Colour function" settings. Clicking on the colour swatch to the right of the slider opens the Colour Picker pane. The slider can be used to quickly darken or lighten the surface material.
    • Colour image: This setting allows you to choose an image file as the basic colour for the surface material. It also acts as a multiplier for the "Base colour" and "Colour function" settings.
    • Colour function: This setting allows you to choose shader or function nodes as the basic colour for the surface material, and acts as a multiplier for the "Base colour" and "Colour image" settings.
    • Translucency: This setting specifies the amount of translucency a surface material has, and acts as a multiplier to the "Translucency image" and "Translucency function" settings. Translucency is the effect of light filtering through a surface, and more information may be found here.
    • Translucency image: This setting allows you to choose an image file to control the translucency of a surface material. It acts as a multiplier to the "Translucency" and "Translucency function" settings.
    • Translucency function: This setting allows you to choose shader or function nodes to control the translucency of a surface material. It acts as a multiplier to the "Translucency" and "Translucency image" settings.
    • Luminosity: This setting specifies the amount of luminosity a surface material has, and acts as a multiplier to the "Luminosity image" and "Luminosity function" settings. Luminosity gives the effect of a glowing or self illuminated surface, and more information may be found here.
    • Luminosity image: This setting allows you to choose an image file to control the luminosity of a surface material. It acts as a multiplier to the "Luminosity" and "Luminosity function" settings.
    • Luminosity function: This setting allows you to choose shader or function nodes to control the luminosity of a surface material. It acts as a multiplier to the "Luminosity" and "Luminosity image" settings.

Roughness Tab[edit]

Roughness Tab

Settings on this tab control the smoothness of a surface material. All the settings are multiplied together and evaluated to determine the final roughness value. When the combined values evaluate to 0 a perfectly smooth surface will result and reflections will be sharp and mirror-like. Rougher surfaces are the result of values closer to 1.0 and will make reflections appear more blurry.

Settings:

    • Roughness: This value should be set to 0 for perfectly smooth surface materials and up to 1.0 for rougher surfaces.
    • Roughness image: This setting allows you to specify an image file to use for roughness.
    • Invert image: When enabled, or checked, the image assigned to the “Roughness image” is inverted, i.e. black becomes white.
    • Gamma image:When enabled, or checked, assumes the image assigned to the “Roughness image” is in sRGB colour space and needs to be converted to linear colour space.
    • Roughness function: This setting allows you to assign shader or function nodes to determine the surface material’s roughness value.
      Roughess settings 0 - 1


Specular Tab[edit]

Specular Tab

Settings:

    • Metalness:
    • Metalness image:
    • Gamma image:
    • Metalness function:
    • Fresnel reflectivity:
    • Reflectivity image:
    • Reflectivity function:
    • Fresnel reflection tint:
    • Index of refraction:

Displacement Tab[edit]

Displacement Tab

The settings found under this tab allow you to control the three dimensional displacement of the surface material. Displacement is only applied if an image is specified in the “Displacement image” setting, or shader or function nodes assigned to the “Displacement function” setting.

Settings:

    • Displacement direction: This popup menu has 5 options which let you choose the direction the displacement is applied in. Options that indicate “(requires computed normal)” require a Compute Terrain or Compute Normal node to be connected somewhere above the Default shader node in the network to work properly.
      Displacment direction options
      • Along vertical: Displacement happens along the normal of the underlying planet or 3D object.
      • Along normal: Displacement happens along the current surface normal.
      • Vertical only (requires computed normal): Displacement only happens along the normal of the underlying planet or 3D object. The displacement is scaled by the difference between the object normal and the surface normal. Displacement is reduced as the angle between the normals approaches 90°.
      • Lateral only (requires computed normal): Displacement only occurs in the lateral plane, that is perpendicular to the normal of the underlying object.
      • Lateral normalized (requires computed normal): This is the same as “Lateral only” but the normal is normalised, that is scaled so it has a length of 1.
      Displace direction: Off
      Displace direction: Along vertical
      Displace direction: Along normal
      Displace direction: Vertical only
      Displace direction: Lateral only
      Displace direction: Lateral normalized
    • Displacement multiplier: This multiplies the displacement values coming from the "Displacement function" input. A value of 1 leaves the incoming values unchanged. A value of 2 would make the incoming values twice as large. A value of 0.5 would make them half as large. Negative values will invert the displacement.
      Direction multiplier = 0.25
      Displacement multiplier = 0.5
      Displacement multiplier = 1.0
    • Displacement image: This setting allows you to specify an image file to use for displacement. The luminance of the image pixels is used to generate displacement.
      Displacement image = gems
      Displacement image = swirls
      Displacement image = Terragen
    • Gamma image:
    • Displacement function: This setting allows you to assign shader or function nodes to use as displacement for the surface material.
      Displacement function = off
      Displacement function = Power fractal
      Displacement function = Power fractal, Displacement image = Terragen
    • Displacement offset: This value is added to incoming displacement values after they are multiplied by the “Displacement multiplier” setting. This creates the effect of offsetting the displacement by a set amount along the “Displacement direction”. Positive values push the displacement out so it looks almost as if it was sitting on a plinth. Negative values will sink the displacement back into the surface. It doesn't reverse the displacement, it's more like creating a hole in the surface and then applying the displacement to the bottom of the hole.
      Displacment modifier = 0 (default)
      Displacement modifier = 1
      Displacement modifier = -1

Opacity Tab[edit]

Opacity Tab

Settings:

    • Opacity:
    • Opacity image:
    • Use alpha channel:
    • Invert opacity image:
    • Opacity function:
    • Alpha from colour:
    • Alpha key:
    • Key tolerance:

Images Tab[edit]

Images Tab

Settings:

    • Image projection:
      Image projection options
    • Projection camera:
    • Unpremultiply colour:
    • Unpremultiply metalness:
    • Unpremultiply translucency:
    • Unpremultiply luminosity:
    • Unpremultiply reflectivity:
    • Unpremultiply specular roughness:

A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.

Literally, to change the position of something. In graphics terminology to displace a surface is to modify its geometric (3D) structure using reference data of some kind. For example, a grayscale image might be taken as input, with black areas indicating no displacement of the surface, and white indicating maximum displacement. In Terragen 2 displacement is used to create all terrain by taking heightfield or procedural data as input and using it to displace the normally flat sphere of the planet.

This is essentially the brightness of the colour. Terragen converts RGB colours to greyscale by taking the luminance of the colour.