Displacement - Revision history

Matt: Removed "Back to the Guide" as I'm moving things around

2019-08-10T07:26:19Z

Removed "Back to the Guide" as I'm moving things around

Matt: /* Using Displacement */

2018-11-13T02:17:34Z

‎Using Displacement

Matt: Edits to conform to new document style guide

2018-11-13T02:15:21Z

Edits to conform to new document style guide

Matt: Added note about Displacement Shader to Scalar, in preference to Displacement Shader to Vector.

2018-11-13T02:11:53Z

Added note about Displacement Shader to Scalar, in preference to Displacement Shader to Vector.

BFlasher: /* Background */

2018-10-18T18:31:09Z

‎Background

BFlasher: /* Using Displacement */

2018-07-13T23:16:43Z

‎Using Displacement

Matt: /* Using Displacement */

2018-05-04T04:09:34Z

‎Using Displacement

Matt at 04:08, 4 May 2018

2018-05-04T04:08:17Z

Matt at 04:07, 4 May 2018

2018-05-04T04:07:15Z

Matt at 03:59, 4 May 2018

2018-05-04T03:59:45Z

← Older revision		Revision as of 07:26, 10 August 2019
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	You might find surfaces with rough or spikey displacement occasionally show problems, such as being cut off at bucket edges or causing gaps in ray traced shadows. Some nodes, such as the [[Planet]], have '''"Displacement tolerance"''' parameters which can help to improve this. Changing this parameter can greatly increase render times so you should only change it if you have a specific need. The default value is 1. If you're having problems try increasing it to 2. If that improves things but doesn't completely resolve them then try increasing it by small increments. You would not generally want to go above a value of 4 or 5 however.		You might find surfaces with rough or spikey displacement occasionally show problems, such as being cut off at bucket edges or causing gaps in ray traced shadows. Some nodes, such as the [[Planet]], have '''"Displacement tolerance"''' parameters which can help to improve this. Changing this parameter can greatly increase render times so you should only change it if you have a specific need. The default value is 1. If you're having problems try increasing it to 2. If that improves things but doesn't completely resolve them then try increasing it by small increments. You would not generally want to go above a value of 4 or 5 however.
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−	~~[[Terragen_4_User_Guide_Part_2:_Fundamental_Rendering_and_Shader_Concepts\|Back to the Guide]]~~

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 An example of this situation is using the [[Simple Shape Shader]] to generate displacement for another node. If you just turn on displacement for the shape shader you won't get any displacement in the node its connected to. However if you turn on colour for the shape shader you will see displacement.
-From v3.0 onwards you can use the [[Displacement Shader to Scalar]] node to convert the output of a displacement shader to a scalar which can be connected to the "Displacement function" input. In earlier versions (from v2.4 onwards) you can use the [[Displacement Shader to Vector]] node for a similar purpose, but be aware that the data conversion is different and may give unexpected results.
+From v3.0 onwards you can use the [[Displacement Shader to Scalar]] node to convert the output of a displacement shader to a scalar which can be connected to the "Displacement function" input. In earlier versions (from v2.4 onwards) you can use the [[Displacement Shader to Vector]] node for a similar purpose, but be aware that [[Displacement Shader to Vector|the data conversion is different and may give unexpected results]].
 '''Displacement offset'''<br />

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 '''Displacement multiplier'''<br />
-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.
+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.
 '''Displacement function'''<br />
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 An example of this situation is using the [[Simple Shape Shader]] to generate displacement for another node. If you just turn on displacement for the shape shader you won't get any displacement in the node its connected to. However if you turn on colour for the shape shader you will see displacement.
-From v3.0 onwards you can use the [[Displacement Shader to Scalar]] node to convert the output of a displacement shader to a scalar which can be connected to the '''Displacement function''' input. In earlier versions (from v2.4 onwards) you can use the [[Displacement Shader to Vector]] node for a similar purpose, but be aware that the data conversion is different and may give unexpected results.
+From v3.0 onwards you can use the [[Displacement Shader to Scalar]] node to convert the output of a displacement shader to a scalar which can be connected to the "Displacement function" input. In earlier versions (from v2.4 onwards) you can use the [[Displacement Shader to Vector]] node for a similar purpose, but be aware that the data conversion is different and may give unexpected results.
 '''Displacement offset'''<br />
-This value is added to incoming displacement values after they are multiplied by the '''Displacement multiplier''' parameter. 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.
+This value is added to incoming displacement values after they are multiplied by the "Displacement multiplier" parameter. 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.
-You might find surfaces with rough or spikey displacement occasionally show problems, such as being cut off at bucket edges or causing gaps in ray traced shadows. Some nodes, such as the [[Planet]], have '''Displacement tolerance''' parameters which can help to improve this. Changing this parameter can greatly increase render times so you should only change it if you have a specific need. The default value is 1. If you're having problems try increasing it to 2. If that improves things but doesn't completely resolve them then try increasing it by small increments. You would not generally want to go above a value of 4 or 5 however.
+You might find surfaces with rough or spikey displacement occasionally show problems, such as being cut off at bucket edges or causing gaps in ray traced shadows. Some nodes, such as the [[Planet]], have '''"Displacement tolerance"''' parameters which can help to improve this. Changing this parameter can greatly increase render times so you should only change it if you have a specific need. The default value is 1. If you're having problems try increasing it to 2. If that improves things but doesn't completely resolve them then try increasing it by small increments. You would not generally want to go above a value of 4 or 5 however.
 [[Terragen_4_User_Guide_Part_2:_Fundamental_Rendering_and_Shader_Concepts|Back to the Guide]]

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 An example of this situation is using the [[Simple Shape Shader]] to generate displacement for another node. If you just turn on displacement for the shape shader you won't get any displacement in the node its connected to. However if you turn on colour for the shape shader you will see displacement.
-From v2.4 on you can use the [[Displacement Shader to Vector]] node to convert the output of a displacement shader to a vector which can be connected to the '''Displacement function''' input. The vector gets converted to a scalar.
+From v3.0 onwards you can use the [[Displacement Shader to Scalar]] node to convert the output of a displacement shader to a scalar which can be connected to the '''Displacement function''' input. In earlier versions (from v2.4 onwards) you can use the [[Displacement Shader to Vector]] node for a similar purpose, but be aware that the data conversion is different and may give unexpected results.
 '''Displacement offset'''<br />

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 ===Background===
-Displacement is technique which is used to give greater shape and detail to surfaces without using precalculated geometry. This means you can take an object made up of relatively few polygons and add much more detail. During rendering scene elements such as the terrain or objects are broken up into micropolygons. Displacement is used to move these micropolygons in 3D space to create more detailed shapes.
+Displacement is a technique which is used to give greater shape and detail to surfaces without using precalculated geometry. This means you can take an object made up of relatively few polygons and add much more detail. During rendering scene elements such as the terrain or objects are broken up into micropolygons. Displacement is used to move these micropolygons in 3D space to create more detailed shapes.
 Displacement is a fundamental part of the Terragen 4 rendering engine. All of the terrain is created by applying displacement to the smooth sphere of the underlying planet, even when using heightfields. Displacement can create features from the size of mountain ranges down to little pebbles. Displacement can also be applied to other parts of a scene, such as objects like rocks or imported 3D models.

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 ===Using Displacement===
-As mentioned above displacement can be used to create very large and very small features. Any large features should be created as part of the terrain rather than as a surface layer. You can do it but we don't recommend it. For best results you should connect any shaders that are generating large displacements into the terrain part of the network. They should be connected above the [[Compute Terrain]] node.
+As mentioned above displacement can be used to create very large and very small features. Any large features should be created as part of the terrain rather than as a surface layer. (You can do it as a surface layer, but we don't recommend it.) For best results you should connect any shaders that are generating large displacements into the terrain part of the network. They should be connected above the [[Compute Terrain]] node.
 Most of the shaders which can generate displacement have a common set of parameters for controlling it. Here's a rundown of how those parameters work:

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 <u>Along normal:</u> Displacement will happen along the current surface normal. This may be the same as "Along vertical" if the normal has not been modified by any other shaders before this one, but there are many situations where other shaders have recalculated the current surface normal so that it changes according to the shape of the surface. One way this can happen is if you have a [[Compute Terrain]] or [[Compute Normal]] shader somewhere upstream in the shader network.
 </li><li>
-<u>Vertical only (requires computed normal):</u> Displacement only happens along the normal of the underlying object (i.e. the planet or a model) as it was before any displacement was applied. On a planet this means that positive displacement will occur upwards and negative displacement will occur downwards. It differs from "Along vertical" in that the displacement is scaled by how similar the surface normal is to the object normal. On a planet this is how much "upwards" the surface normal is (how horizontal the surface is), so horizontal surfaces will be most affected by displacement and side-facing surfaces will be least affected. On other objects "upwards" means the normal of the surface of the underlying object as it was before any displacement.
+<u>Vertical only (requires computed normal):</u> Displacement only happens along the normal of the underlying object (i.e. the planet or a model) as it was before any displacement was applied. On a planet this means that positive displacement will occur upwards and negative displacement will occur downwards. It differs from <u>Along vertical</u> in that the displacement is scaled by how similar the surface normal is to the object normal. On a planet this is how much "upwards" the surface normal is (how horizontal the surface is), so horizontal surfaces will be most affected by displacement and side-facing surfaces will be least affected. On other objects "upwards" means the normal of the surface of the underlying object as it was before any displacement.
 </li><li>
 <u>Lateral only (requires computed normal):</u> Displacement only occurs in directions that are at 90&deg; to the normal of the underlying object. On a planet this means it will only displace sideways, not up or down, and this can only happen if the surface normal has been calculated or redirected using other shaders before this one. The displacement is scaled by the difference between the object normal and the surface normal. On a planet this is how much "sideways" the surface normal is, so side-facing surfaces will be most affected by displacement and horizontal surfaces will be least affected. On other objects "sideways" means any tangent to the surface of the underlying object as it was before any displacement.

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 <u>Vertical only (requires computed normal):</u> Displacement only happens along the normal of the underlying object (i.e. the planet or a model) as it was before any displacement was applied. Usually on a planet this means that positive displacement will occur upwards and negative displacement will occur downwards. It differs from "Along vertical" in that the displacement is scaled by how similar the surface normal is to the object normal. On a planet this is how much "upwards" the surface normal is (how horizontal the surface is), so horizontal surfaces will be most affected by displacement and side-facing surfaces will be least affected. On other objects "upwards" means the normal of the surface of the underlying object as it was before any displacement.
 </li><li>
-<u>Lateral only (requires computed normal):</u> Displacement only occurs in the lateral plane, or in other words perpendicular to the normal of the underlying object. Usually on a planet this means it will only displace sideways, not up or down. The displacement is scaled by the difference between the object normal and the surface normal. On a planet this is how much "sideways" the surface normal is, so side-facing surfaces will be most affected by displacement and horizontal surfaces will be least affected. On other objects "sideways" means the tangent to the surface of the underlying object as it was before any displacement.
+<u>Lateral only (requires computed normal):</u> Displacement only occurs in the lateral plane, or in other words perpendicular to the normal of the underlying object. Usually on a planet this means it will only displace sideways, not up or down. The displacement is scaled by the difference between the object normal and the surface normal. On a planet this is how much "sideways" the surface normal is, so side-facing surfaces will be most affected by displacement and horizontal surfaces will be least affected. On other objects "sideways" means any tangent to the surface of the underlying object as it was before any displacement.
 </li><li>
 <u>Lateral normalized (requires computed normal):</u> This is the same as <u>Lateral only</u> but the normal is normalised (scaled so it has a length of 1).