Reference:Media - Revision history

Jr: fix typos and wording.

2025-06-12T15:15:57Z

fix typos and wording.

Jholsenback: technical correction

2021-02-12T15:36:13Z

technical correction

Jholsenback: link repair after build error

2016-12-17T16:50:58Z

link repair after build error

Jholsenback: moved sub-sections to individual files

2016-12-17T16:03:49Z

moved sub-sections to individual files

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Clipka: Indexentries fix

2016-12-17T01:21:56Z

Indexentries fix

Jholsenback: paragraph cleanup and additional clarification

2012-08-24T14:34:27Z

paragraph cleanup and additional clarification

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Jholsenback: paragraph repair

2012-08-23T19:19:36Z

paragraph repair

Jholsenback: 1 revision: reference layout changes

2012-08-08T13:11:26Z

1 revision: reference layout changes

Jholsenback: cleanup round 2

2012-08-07T01:28:45Z

cleanup round 2

Jholsenback: 1 revision: link repair

2012-07-23T19:27:51Z

1 revision: link repair

@@ Line 2: / Line 2: @@
 {{#indexentry:media, reference}}
 <!--<sectiondesc desc=<"media reference">--->
-<p>The <code>media</code> statement is used to specify particulate matter suspended in a medium such air or water. It can be used to specify smoke, haze, fog, gas, fire, dust etc. Previous versions of POV-Ray had two incompatible systems for generating such effects. One was <code>halo</code> for effects enclosed in a transparent or semi-transparent object. The other was <code>atmosphere</code> for effects that permeate the entire scene. This duplication of systems was complex and unnecessary. Both <code>halo</code>
+<p>The <code>media</code> statement is used to specify particulate matter suspended in a medium such as air or water. It can be used to model smoke, haze, fog, gas, fire, dust etc. Previous versions of POV-Ray had two incompatible systems for generating such effects. One was <code>halo</code> for effects enclosed in a transparent or semi-transparent object. The other was <code>atmosphere</code> for effects that permeate the entire scene. This duplication of systems was complex and unnecessary. Both <code>halo</code>
 and <code>atmosphere</code> have been eliminated. See [[Reference:Interior#Why are Interior and Media Necessary?|Why are Interior and Media Necessary?]] for further details on this change. See [[Reference:Interior#Object-Media|Object Media]]
-for details on how to use <code>media</code> with objects. See [[Reference:Atmospheric Media|Atmospheric Media]] for details on using <code>media</code> for atmospheric effects outside of objects. This section and the sub-sections which follow explains the details of the various <code>media</code> options which are useful for either object media or atmospheric media.</p>
+for details on how to use <code>media</code> with objects. See [[Reference:Atmospheric Media|Atmospheric Media]] for details on using <code>media</code> for atmospheric effects outside of objects. This section and the sub-sections which follow explain the details of the various <code>media</code> options which are useful for either object media or atmospheric media.</p>
 <p>Media works by sampling the density of particles at some specified number of points along the ray's path. Sub-samples are also taken until the results reach a specified confidence level. POV-Ray provides three methods of sampling. When used in an object's <code>interior</code> statement, sampling only occurs inside the object. When used for atmospheric media, the samples run from
-the camera location until the ray strikes an object. Therefore for localized effects, it is best to use an enclosing object even though the density pattern might only produce results in a small area whether the media was enclosed or not.</p>
+the camera location until the ray strikes an object. Therefore, for localized effects it is best to use an enclosing object even though the density pattern might only produce results in a small area, whether the media was enclosed or not.</p>
 <p>The complete syntax for a <code>media</code> statement is as follows:</p>
@@ Line 53: / Line 53: @@
 </pre>
-<p>If a media identifier is specified, it must be the first item. All other media items may be specified in any order. All are optional. You may have multiple <code>density</code> statements in a single <code>media</code> statement. See [[Reference:Density#Multiple Density vs. Multiple Media|Multiple Density vs. Multiple Media]] for details. Transformations apply only to the <code>density</code> statements which have been already specified. Any <code>density</code> after a transformation is not affected. If the <code>media</code> has no <code>density</code> statements and none was specified in any media identifier, then the transformation has no effect. All other media items except for <code>density</code> and transformations override default values or any previously set values for this <code>media</code> statement.</p>
+<p>If a media identifier is specified, it must be the first item. All other media items may be specified in any order, all are optional. You may have multiple <code>density</code> statements in a single <code>media</code> statement. See [[Reference:Density#Multiple Density vs. Multiple Media|Multiple Density vs. Multiple Media]] for details. Transformations apply only to the <code>density</code> statements which have been already specified. Any <code>density</code> after a transformation is not affected. If the <code>media</code> has no <code>density</code> statements and none was specified in any media identifier, then the transformation has no effect. All other media items, except for <code>density</code> and transformations, override default values or any previously set values for this <code>media</code> statement.</p>
 <p class="Note"><strong>Note:</strong> Some media effects depend upon light sources. However the participation of a light source depends upon the <code>media_interaction</code> and <code>media_attenuation</code> keywords. See [[Reference:Light Source#Atmospheric Media Interaction|Atmospheric Media Interaction]] and [[Reference:Light Source#Atmospheric Attenuation|Atmospheric Attenuation]] for details.</p>
 <p class="Note"><strong>Note:</strong> If you specify <code>[[Reference:Color Expressions#Color Keywords|:transmit|transmit]]</code> or <code>[[Reference:Color Expressions#Color Keywords|:filter|filter]]</code> to create a transparent container object, <code>absorption</code> media will always cast a shadow. The same applies to <code>scattering</code> media unless <code>extinction</code> is set to zero, so if a shadow is not desired, use the <code>no_shadow</code> keyword for the container object. This does not apply to <code>emission</code> media as it never casts a shadow.</p>

@@ Line 45: / Line 45: @@
 method       : 3
 ratio        : 0.9
-samples      : Min 1, Max 1
+samples      : 10
 variance     : 1/128
 SCATTERING

@@ Line 53: / Line 53: @@
 </pre>
-<p>If a media identifier is specified, it must be the first item. All other media items may be specified in any order. All are optional. You may have multiple <code>density</code> statements in a single <code>media</code> statement. See [[Reference:Media#Multiple Density vs. Multiple Media|Multiple Density vs. Multiple Media]] for details. Transformations apply only to the <code>density</code> statements which have been already specified. Any <code>density</code> after a transformation is not affected. If the <code>media</code> has no <code>density</code> statements and none was specified in any media identifier, then the transformation has no effect. All other media items except for <code>density</code> and transformations override default values or any previously set values for this <code>media</code> statement.</p>
+<p>If a media identifier is specified, it must be the first item. All other media items may be specified in any order. All are optional. You may have multiple <code>density</code> statements in a single <code>media</code> statement. See [[Reference:Density#Multiple Density vs. Multiple Media|Multiple Density vs. Multiple Media]] for details. Transformations apply only to the <code>density</code> statements which have been already specified. Any <code>density</code> after a transformation is not affected. If the <code>media</code> has no <code>density</code> statements and none was specified in any media identifier, then the transformation has no effect. All other media items except for <code>density</code> and transformations override default values or any previously set values for this <code>media</code> statement.</p>
 <p class="Note"><strong>Note:</strong> Some media effects depend upon light sources. However the participation of a light source depends upon the <code>media_interaction</code> and <code>media_attenuation</code> keywords. See [[Reference:Light Source#Atmospheric Media Interaction|Atmospheric Media Interaction]] and [[Reference:Light Source#Atmospheric Attenuation|Atmospheric Attenuation]] for details.</p>
 <p class="Note"><strong>Note:</strong> If you specify <code>[[Reference:Color Expressions#Color Keywords|:transmit|transmit]]</code> or <code>[[Reference:Color Expressions#Color Keywords|:filter|filter]]</code> to create a transparent container object, <code>absorption</code> media will always cast a shadow. The same applies to <code>scattering</code> media unless <code>extinction</code> is set to zero, so if a shadow is not desired, use the <code>no_shadow</code> keyword for the container object. This does not apply to <code>emission</code> media as it never casts a shadow.</p>

@@ Line 59: / Line 59: @@
 <p class="Note"><strong>Note:</strong> If you specify <code>[[Reference:Color Expressions#Color Keywords|:transmit|transmit]]</code> or <code>[[Reference:Color Expressions#Color Keywords|:filter|filter]]</code> to create a transparent container object, <code>absorption</code> media will always cast a shadow. The same applies to <code>scattering</code> media unless <code>extinction</code> is set to zero, so if a shadow is not desired, use the <code>no_shadow</code> keyword for the container object. This does not apply to <code>emission</code> media as it never casts a shadow.</p>
 {{#indexentry:media, types}}
 <p>There are three types of particle interaction in <code>media</code>: absorbing, emitting, and scattering. All three activities may occur in a single media. Each of these three specifications requires a color. Only the red, green, and blue components of the color are used. The filter and transmit values are ignored. For this reason it is permissible to use one float value to specify an intensity of white color. For example, the following two lines are legal and produce the same results:</p>
@@ Line 68: / Line 68: @@
 </pre>
 {{#indexentry:absorption, media}}
 {{#indexentry:keyword, absorption}}
 <p>The <code>absorption</code> keyword specifies a color of light which is absorbed when looking through the media. For example, <code>absorption rgb&lt;0,1,0&gt;</code> blocks the green light but permits red and blue to get through. Therefore a white object behind the media will appear magenta. The default value is <code>rgb&lt;0,0,0&gt;</code> which means no light is absorbed, meaning all light passes through normally.</p>
 {{#indexentry:emission, media}}
 {{#indexentry:keyword, emission}}
 <p>The <code>emission</code> keyword specifies the color of the light emitted from the particles. Particles which emit light are visible without requiring additional illumination. However, they will only illuminate other objects if radiosity is used with media on.  This is similar to an object with high <code>ambient</code> values. The default value is <code>rgb&lt;0,0,0&gt;</code> which means no light is emitted.</p>
 {{#indexentry:scattering, media}}
 {{#indexentry:keyword, scattering}}
 <p>The syntax of a <code>scattering</code> statement is:</p>
@@ Line 154: / Line 154: @@
 <p class="Note"><strong>Note:</strong> See the section on [[Reference:Light Group|Light Groups]] for additional information when using scattering media in a light group.</p>
 {{#indexentry:method, media}}
 {{#indexentry:keyword, method}}
 {{#indexentry:intervals, media}}
 {{#indexentry:keyword, intervals}}
 <p>Media effects are calculated by sampling the media along the path of the ray. It uses a process called <em>Monte Carlo integration.</em> POV-Ray provides three different types of media sampling. The <code>method</code> keyword lets you specify what sampling type is used.</p>
@@ Line 196: / Line 196: @@
 <code>jitter</code> will cause method 2 to look similar to method 1. It should be followed by a float, and a value of 1 will stagger the samples in the full range between samples.</p>
 {{#indexentry:density, media}}
 {{#indexentry:keyword, density}}
 <p>Particles of media are normally distributed in constant density throughout the media. However, the <code>density</code> statement allows you to vary the density across space using any of POV-Ray's pattern functions such as those used in textures. If no <code>density</code> statement is given then the density remains a constant value of 1.0 throughout the media. More than one <code>density</code> may be specified per <code>media</code> statement. See [[Reference:Media#Multiple Density vs. Multiple Media|Multiple Density vs. Multiple Media]].</p>
@@ Line 222: / Line 222: @@
 <p>A <code>density</code> statement may be modified by any of the general pattern modifiers such as transformations, <code>turbulence</code> and <code>warp</code>. See [[Reference:Pattern Modifiers|Pattern Modifiers]] for details. In addition, there are several density-specific modifiers which can be used.</p>
 {{#indexentry:color_map, density}}
 <p>Typically, a <code>media</code> uses just one constant color throughout. Even if you vary the density, it is usually just one color which is specified by the <code>absorption</code>, <code>emission</code>, or <code>scattering</code> keywords. However, when using <code>emission</code> to simulate fire or explosions, the center of the flame (high density area) is typically brighter and white or yellow. The outer edge of the flame (less density) fades to orange, red, or in some cases deep blue. To model the density-dependent change in color which is visible, you may specify a <code>color_map</code>. The pattern function returns a value from 0.0 to 1.0 and the value is passed to the color map to compute what color or blend of colors is used. See [[Reference:Color Map|Color Maps]] for details on how pattern values work with <code>color_map</code>. This resulting color is multiplied by the <code>absorption</code>, <code>emission</code> and <code>scattering</code> color. Currently there is no way to specify different color maps for each media type within the same <code>media</code> statement.</p>
@@ Line 257: / Line 257: @@
 <p>See [[Reference:Pigment#Color List Pigments|Color List Pigments]] which describes how <code>pigment</code> uses a color list. The same principles apply when using them with <code>density</code>.</p>
 {{#indexentry:keyword, density_map}}
 <p>In addition to specifying blended colors with a color map you may create a blend of densities using a <code>density_map</code>. The syntax for a density map is identical to a color map except you specify a density in each map entry (and not a color).</p>

← Older revision		Revision as of 19:19, 23 August 2012
Line 419:		Line 419:
	</pre>		</pre>

−	<p>In this case each media is computed independently. The resulting colors	+	<p>In this case each media is computed independently. The resulting colors are added together. Suppose one density and media returned <code>rgb<.8,.8,.4></code> and the other returned <code>rgb<.25,.25,0></code>. The resulting color is <code>rgb<1.05,1.05,.4></code>. The end result is that density areas which overlap will be especially bright and all areas will be visible. This is similar to a [[Reference:Constructive Solid Geometry\|:CSG\|CSG]] [[Reference:Union\|:union\|union]] operation.See the sample scene <code>~scenes\interior\media\media4.pov</code> for an example which illustrates this.</p>
−	are added together. Suppose one density and media returned <code>
−	rgb<.8,.8,.4></code> and the other returned <code>
−	rgb<.25,.25,0></code>. The resulting color is <code>
−	rgb<1.05,1.05,.4></code>. The end result is that density areas which
−	overlap will be especially bright and all areas will be visible. This is
−	similar to a [[Reference:Constructive Solid Geometry\|:CSG\|CSG]] [[Reference:Union\|:union\|union]] operation.
−	See the sample scene <code>~scenes\interior\media\media4.pov</code> for an example
−	which illustrates this.</p>

← Older revision	Revision as of 13:11, 8 August 2012
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@@ Line 425: / Line 425: @@
 rgb&lt;1.05,1.05,.4&gt;</code>. The end result is that density areas which
 overlap will be especially bright and all areas will be visible. This is
-similar to a [[Reference:Object#Constructive Solid Geometry|:CSG|CSG]] [[Reference:Union|:union|union]] operation.
+similar to a [[Reference:Constructive Solid Geometry|:CSG|CSG]] [[Reference:Union|:union|union]] operation.
 See the sample scene <code>~scenes\interior\media\media4.pov</code> for an example
 which illustrates this.</p>

← Older revision	Revision as of 19:27, 23 July 2012
(No difference)