Compositing Terragen Render Elements - Revision history

Redmaw: Added description and example images for Sample Rate render element.

2022-02-24T18:12:33Z

Added description and example images for Sample Rate render element.

Redmaw: Added description and example image for using Terragen's chromatic alpha channels to add Terragen render elements on top of non-Terragen render elements.

2022-02-24T00:57:46Z

Added description and example image for using Terragen's chromatic alpha channels to add Terragen render elements on top of non-Terragen render elements.

Redmaw: Updated Normal render element's description and replaced old image with new example.

2020-03-18T17:22:01Z

Updated Normal render element's description and replaced old image with new example.

Redmaw: Added Surface Diffuse Colour section

2020-03-17T18:17:33Z

Added Surface Diffuse Colour section

Redmaw: Added Normal render element to wiki page

2020-03-16T21:50:02Z

Added Normal render element to wiki page

Redmaw: fixed typo

2020-03-10T02:44:30Z

fixed typo

Redmaw: /* Data Elements */

2020-03-10T02:41:09Z

‎Data Elements

Matt: Added two main section headers

2020-03-09T23:53:35Z

Added two main section headers

Redmaw: Added tgAlpha section, and data sections, zdepth, 2d motion, & position

2020-03-09T21:28:26Z

Added tgAlpha section, and data sections, zdepth, 2d motion, & position

Redmaw: Incorporated Matt's suggestions, increased image size to 867, added section headers and table of contents for organization.

2020-03-03T17:39:35Z

Incorporated Matt's suggestions, increased image size to 867, added section headers and table of contents for organization.

← Older revision		Revision as of 18:12, 24 February 2022
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	[[File:CmpRndElm_17_tgSurfDiffCol.jpg\|none\|867px\|tgSurfDiffCol]]		[[File:CmpRndElm_17_tgSurfDiffCol.jpg\|none\|867px\|tgSurfDiffCol]]
		+
		+
		+	==Sample Rate==
		+
		+	The Sample Rate render element shows the distribution of “ray-traced subpixel samples” by the adaptive sampler. The colours represent a percentage of the maximum possible samples for a given anti-aliasing value. For example, 64 is the maximum possible samples for an anti-aliasing value of 8.
		+
		+	[[File:CmpRndElm_07_RenderPixelSampler_AA8_64Samples.png\|none\|470px\|Pixel Sampler window showing anti-aliasing value set to 8, and the maximum number of possible samples, 64.]]
		+
		+
		+	When viewing the image as an EXR, clamp the values at 1 (white) for ideal viewing. When clamped, the relationship of colour to the maximum possible samples is as follows:
		+
		+	* Fully white pixels = 100%
		+	* Magenta pixels = 10%
		+	* Blue pixels = 1%
		+	* Black pixels = 0 samples.
		+
		+	Note, that although a pixel might contain no samples, interpolation occurs wherever samples are sparse.
		+
		+	When viewing as an unclamped EXR, the green channel goes from 0 to 1 to represent the fraction of samples, while the red and blue channels may exceed 1 as they are equal to the green channel multiplied by 10 and 100, respectively.
		+	{\|
		+	\|-
		+	\| [[File:CmpRndElm_08_SampleRate_Clamped.JPG\|none\|800px\|Close up detail showing pixel values when clamped and unclamped.]]
		+	\|-
		+	\| [[File:CmpRndElm_09_SampleRateElement.JPG\|none\|800px\|Sample Rate render element.]]
		+	\|}
		+
		+	<br /n>

← Older revision		Revision as of 00:57, 24 February 2022
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	[[File:CmpRndElm_07_tgAlpha.jpg\|none\|867px\|tgAlpha = tgSurfAlpha + tgAtmoAlpha + tgCloudAlpha]]		[[File:CmpRndElm_07_tgAlpha.jpg\|none\|867px\|tgAlpha = tgSurfAlpha + tgAtmoAlpha + tgCloudAlpha]]

		+
		+	A question often asked is “Why does the alpha channel image contain colour values?” and “How do I use it?”
		+
		+
		+	In Terragen, the Rayleigh scattering feature takes into account that the atmosphere’s opacity can vary at different wavelengths, and this information can be recorded in the red, green and blue channels of a rendered image. This is called a “Chromatic” alpha channel, and by using the RGB channels instead of the familiar alpha channel, which only contains one value per pixel, you have more accurate control over any post production changes you might want to make, especially to the cloud layers and atmosphere.
		+
		+
		+	To use the chromatic alpha channel, you first need to multiply an inverted version of it over the non-Terragen background render element. Then merge any Terragen RGB render elements on top using Additive mode.
		+	<ul>
		+	* Invert the chromatic alpha channel by adding a Channel Boolean node, with its Operation mode set to negative.
		+	* Merge the inverted chromatic alpha channel with the non-Terragen render element, setting the Apply Mode to multiply.
		+	* Merge the Terragen RGB render element, such as the tgRGB, in additive mode. In Fusion Studio, this means the Apply Mode = Normal, Operator = Over, and Alpha Gain = 0.
		+	</ul>
		+
		+
		+	[[File:CmpRndElm_06_ChromaticAlphaChannels_0001.jpg\|none\|867px\|Compositing the Terragen rendered elements on top of a non-Terragen element using the chromatic alpha channels.]]

@@ Line 101: / Line 101: @@
 ==Normals==
-The “tgSurfNormal” render element contains data describing the 3D vector of a line perpendicular to the surface of an object or terrain.  Each pixel channel contains values from -1.0 to +1.0.  The X Normals are mapped to the Red channel, and values below 0.0 to -1.0 indicate the underlying geometry is pointing to the left, while values above 0.0 to +1.0 point to the right.  The Y Normals are mapped to the Green channel, and the lower values point down while the higher values point up.  The Z Normals are mapped to the Blue channel and indicate whether the vector points towards or away from the camera.
+The “tgSurfNormal” render element contains data describing the 3D vector of a line perpendicular to the surface of an object or terrain, in world space.  Each pixel channel contains values from -1.0 to +1.0.  The X Normals are mapped to the Red channel, and values below 0.0 to -1.0 indicate the underlying geometry is pointing in the direction of the -X axis in world space, while values above 0.0 to +1.0 point towards the +X axis. The Y Normals are mapped to the Green channel, and values lower than 0.0 point downward while values above 0.0 point upwards.  The Z Normals are mapped to the Blue channel and values below 0.0 point towards the -Z axis, while values above 0.0 point towards the +Z axis in world space.
-[[File:CompositRenderElements_tgSurfNormal_v001.jpg|none|867px|tgSurfNormal]]
+Depending on the compositing software being used, it may be necessary to reverse the Z channel and/or swap Y and Z channels if you need to combine the render element with normal passes from other software.

← Older revision		Revision as of 18:17, 17 March 2020
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	[[File:CompositRenderElements_tgSurfNormal_v001.jpg\|none\|867px\|tgSurfNormal]]		[[File:CompositRenderElements_tgSurfNormal_v001.jpg\|none\|867px\|tgSurfNormal]]
		+
		+
		+	==Surface Diffuse Colour==
		+
		+	The "tgSurfDiffColor" render element contains an object or terrain's diffuse color values before any lighting is applied.
		+
		+	One way in which it can be used is to create masks based on the color values.
		+
		+	[[File:CmpRndElm_17_tgSurfDiffCol.jpg\|none\|867px\|tgSurfDiffCol]]

← Older revision		Revision as of 21:50, 16 March 2020
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	[[File:CmpRndElm_15_tgCloudPos.jpg\|none\|867px\|tgSurfPos combined with tgCloudPos]]		[[File:CmpRndElm_15_tgCloudPos.jpg\|none\|867px\|tgSurfPos combined with tgCloudPos]]
		+
		+
		+	==Normals==
		+
		+	The “tgSurfNormal” render element contains data describing the 3D vector of a line perpendicular to the surface of an object or terrain. Each pixel channel contains values from -1.0 to +1.0. The X Normals are mapped to the Red channel, and values below 0.0 to -1.0 indicate the underlying geometry is pointing to the left, while values above 0.0 to +1.0 point to the right. The Y Normals are mapped to the Green channel, and the lower values point down while the higher values point up. The Z Normals are mapped to the Blue channel and indicate whether the vector points towards or away from the camera.
		+
		+	[[File:CompositRenderElements_tgSurfNormal_v001.jpg\|none\|867px\|tgSurfNormal]]

@@ Line 92: / Line 92: @@
 ==Position==
-The “tgSurfPos” and “tgCloudPos” render elements contain data that describes the position of a point on a surface or cloud layer respectively, in world space.  World position in measured in meters and in Terragen's coordinate space.  Sometimes it may be necessary to reverse the Z channel and/or swap Y and Z channels if you need to combine the render element with position passes from other software.
+The “tgSurfPos” and “tgCloudPos” render elements contain data that describes the position of a point on a surface or cloud layer respectively, in world space.  World position is measured in meters and in Terragen's coordinate space.  Sometimes it may be necessary to reverse the Z channel and/or swap Y and Z channels if you need to combine the render element with position passes from other software.
 [[File:CmpRndElm_14_tgSurfPos.jpg|none|867px|tgSurfPos]]
 [[File:CmpRndElm_15_tgCloudPos.jpg|none|867px|tgSurfPos combined with tgCloudPos]]

← Older revision		Revision as of 23:53, 9 March 2020
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		+	= Rebuilding the Image from Lighting Elements =
		+
	Compositing with Terragen's render elements allows you to recreate and fine-tune the final rendered image or "beauty pass". The compositing project should be set up in linear colour space and you will use an "Additive" workflow approach, which means setting the render element's merge or blending mode to the equivealent of "additive" in your 2d software package. In the Nuke software, this means setting the merge node to "Plus", while in the Fusion software, this means setting the merge node's "Apply Mode" to "Normal", "Operator" to "Over", and "Alpha Gain" to "0.0".		Compositing with Terragen's render elements allows you to recreate and fine-tune the final rendered image or "beauty pass". The compositing project should be set up in linear colour space and you will use an "Additive" workflow approach, which means setting the render element's merge or blending mode to the equivealent of "additive" in your 2d software package. In the Nuke software, this means setting the merge node to "Plus", while in the Fusion software, this means setting the merge node's "Apply Mode" to "Normal", "Operator" to "Over", and "Alpha Gain" to "0.0".

Line 61:		Line 63:


		+	= Data Elements =

	Terragen can also save render elements for data that is often used by compositors in order to create masks within the compositing software. Please be aware that each compositing package will have its own way of extracting the data.		Terragen can also save render elements for data that is often used by compositors in order to create masks within the compositing software. Please be aware that each compositing package will have its own way of extracting the data.

← Older revision		Revision as of 21:28, 9 March 2020
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	In the image below we can see the compositing node layout and the results of the “additive” workflow.		In the image below we can see the compositing node layout and the results of the “additive” workflow.
	[[File:CmpRndElm_06_ReplaceAll.jpg\|none\|867px\|Composite using render elements.]]		[[File:CmpRndElm_06_ReplaceAll.jpg\|none\|867px\|Composite using render elements.]]
		+
		+
		+	==tgAlpha==
		+
		+	The “tgAlpha” channel can also be reconstructed with alternate render layers:
		+	tgAlpha = tgSurfAlpha + tgAtmoAlpha + tgCloudAlpha
		+
		+	[[File:CmpRndElm_07_tgAlpha.jpg\|none\|867px\|tgAlpha = tgSurfAlpha + tgAtmoAlpha + tgCloudAlpha]]
		+
		+
		+
		+
		+	Terragen can also save render elements for data that is often used by compositors in order to create masks within the compositing software. Please be aware that each compositing package will have its own way of extracting the data.
		+
		+	==Z-Depth==
		+	There are two depth render layers available, one for "Surface Depth" and the other for "Cloud Depth". This type of data is often referred to as a depth map or Z-depth. The data records the distance between the camera and an object or terrain, or a cloud.
		+
		+	In this example, I've added a layer of smog over the Terragen beauty pass render element by passing the data stored in the tgSurfDepth render element to the composting software's fog filter.
		+	[[File:CmpRndElm_08_tgSurfDepth.jpg\|none\|867px\|tgSurfDepth]]
		+
		+
		+	In this next example, the tgSurfDepth render element and the tgCloudDepth render element have been combined and passed along to the compositing software's fog filter to create a layer of smog in the foreground.
		+	[[File:CmpRndElm_09_tgCloudDepth.jpg\|none\|867px\|tgSurfDepth combined with tgCloudDepth]]
		+
		+
		+
		+	==2d Motion==
		+	There are two motion vector render elements available, one for "Surface Motion" and the other for "Cloud Motion".
		+
		+	The "tgSurf2dMotion" render element contains data that describes the motion of objects within the image or frame. The X vector and Y vector values are stored in the red and green channels of the image. In CGI it's typically faster to render without realistic 3d motion blur, but by saving the 2d vector data an approximation of the motion blur can be made within the compositing software.
		+	[[File:CmpRndElm_10_tgSurf2dMotion.jpg\|none\|867px\|tgSurf2dMotion]]
		+
		+
		+	The "tgCloud2dMotion" render element contains data that describes the motion of the cloud layers within the image or frame. In the example below note how by using this render element we can isolate the cloud layers and apply 2d vector blur to only the cloud layers.
		+	[[File:CmpRndElm_11_tgCloud2dMotion.jpg\|none\|867px\|tgCloud2dMotion]]
		+
		+
		+	==Position==
		+
		+	The “tgSurfPos” and “tgCloudPos” render elements contain data that describes the position of a point on a surface or cloud layer respectively, as seen from the camera.
		+	[[File:CmpRndElm_12_tgSurfPos.jpg\|none\|867px\|tgSurfPos]]
		+
		+
		+	[[File:CmpRndElm_13_tgCloudPos.jpg\|none\|867px\|tgSurfPos combined with tgCloudPos]]

@@ Line 1: / Line 1: @@
 The simplest example of combining render elements to match the Terragen beauty pass, which is sufficient for many projects, is this:
 '''tgRgb = tgSurfRgb + tgAtmoRgb + tgCloudRgb'''
-[[File:CmpRndElm_01_tgSurf.jpg|none|800px|tgRgb = tgSurfRgb + tgAtmoRgb + tgCloudRgb]]
+[[File:CmpRndElm_01_tgSurf.jpg|none|867px|tgRgb = tgSurfRgb + tgAtmoRgb + tgCloudRgb]]
 Note that each of these render elements are blended or merged together in an "additive" way, and that the end result matches the Terragen beauty pass.
-For example, in the Nuke compositing software you would set the Merge node to “Plus”.  In the Fusion compositing software you set the Merge node’s “Apply Mode” value to “Normal”, the “Operator” value to “Over” and the “Alpha Gain” to “0.0”.
+==tgSurfRgb==
 Sometimes you'll want to adjust or fine-tune your image, so each of the three "Rgb" render elements above can be recreated by combining other render elements.  The newly combined elements then replace the "Rgb" render element in the comp.
@@ Line 16: / Line 19: @@
 '''tgSurfRgb = tgSurfDirect + tgSurfIndirect'''.
-[[File:CmpRndElm_02_tgSurf_Meth01.jpg|none|800px|tgSurfRgb = tgSurfDirect + tgSurfIndirect]]
+[[File:CmpRndElm_02_tgSurf_Meth01.jpg|none|867px|tgSurfRgb = tgSurfDirect + tgSurfIndirect]]
@@ Line 22: / Line 25: @@
 '''tgSurfRgb = tgSurfDirectDiff + tgSurfDirectSpec + tgSurfIndirectDiff + tgSurfIndirectSpec'''.
-[[File:CmpRndElm_03_tgSurf_Meth02.jpg|none|800px|tgSurfRgb = tgSurfDirectDiff + tgSurfDirectSpec + tgSurfIndirectDiff + tgSurfIndirectSpec]]
+[[File:CmpRndElm_03_tgSurf_Meth02.jpg|none|867px|tgSurfRgb = tgSurfDirectDiff + tgSurfDirectSpec + tgSurfIndirectDiff + tgSurfIndirectSpec]]
 As you can see, using either of these methods results in matching the Terragen beauty pass, and adds the ability to "dial in" the amount of surface lighting you want.
@@ Line 30: / Line 35: @@
 '''tgAtmoRgb = tgAtmoDirect + tgAtmoIndirect'''
-[[File:CmpRndElm_04_tgAtmo.jpg|none|800px|tgAtmoRgb = tgAtmoDirect + tgAtmoIndirect]]
+[[File:CmpRndElm_04_tgAtmo.jpg|none|867px|tgAtmoRgb = tgAtmoDirect + tgAtmoIndirect]]
 And finally, the clouds "tgCloudRgb" render element can be recreated in a similar fashion, by combining the "tgCloudDirect" and "tgCloudIndirect" render elements.
 '''tgCloudRgb = tgCloudDirect + tgCloudIndirect'''
-[[File:CmpRndElm_05_tgCloud.jpg|none|800px|tgCloudRgb = tgCloudDirect + tgCloudIndirect]]
+[[File:CmpRndElm_05_tgCloud.jpg|none|867px|tgCloudRgb = tgCloudDirect + tgCloudIndirect]]
 In the image below we can see the compositing node layout and the results of the “additive” workflow.
-[[File:CmpRndElm_06_ReplaceAll.jpg|none|800px|Composite using render elements.]]
+[[File:CmpRndElm_06_ReplaceAll.jpg|none|867px|Composite using render elements.]]