POV-Wiki - User contributions [en]

Documentation Talk:Reference Section 5

2009-07-24T02:27:32Z

TimA: Created page with 'The section on image_map should reference function images... IMAGE_MAP: image_map { FUNCTION_IMAGE | [BITMAP_TYPE] "bitmap[.ext]" [IMAGE_MAP_MODS...] } FUNCT…'

The section on image_map should reference function images...

IMAGE_MAP:
image_map {
FUNCTION_IMAGE | [BITMAP_TYPE] "bitmap[.ext]"
[IMAGE_MAP_MODS...]
}
FUNCTION_IMAGE:
function I_WIDTH, I_HEIGHT { FUNCTION_IMAGE_BODY }
FUNCTION_IMAGE_BODY:
PIGMENT | FN_FLOAT | pattern { PATTERN [PATTERN_MODIFIERS] }
BITMAP_TYPE:
gif | tga | iff | ppm | pgm | png | jpeg | tiff | sys
IMAGE_MAP_MOD:
map_type Type | once | interpolate Type |
filter Palette, Amount | filter all Amount |
transmit Palette, Amount | transmit all Amount

For syntax of function images see "Function Image".

After the optional BITMAP_TYPE keyword is a string expression ... etc.

Help talk:Namespaces

2008-01-04T12:38:20Z

TimA:

Documentation: 
HowTo: 
Knowledgebase:

Help talk:Namespaces

2008-01-04T12:37:50Z

TimA: New page: Documentation: HowTo: Knowledgebase:

Documentation:
HowTo:
Knowledgebase:

HowTo:Use radiosity

2007-12-28T01:48:35Z

TimA: /* Shortcuts */

==Radiosity==
Radiosity, also known as global illumination (GI), is a process of
calculating diffuse reflecting light in a scene. To use radiosity, include a
radiosity block in the global settings. Please note that the default setting
for an empty radiosity block is very low quality, if you are unfamiliar with
the fourteen different settings that control the look and performance of
POV’s radiosity algorithm the easiest way to get started is to use the
Rad_Settings macro from rad_def.inc, followed by a boolean for normals
and a boolean for medias. The pre-sets from rad_def.inc are...
*Radiosity_Default
*Radiosity_Debug
*Radiosity_Fast
*Radiosity_Normal
*Radiosity_2Bounce
*Radiosity_Final
*Radiosity_OutdoorLQ
*Radiosity_OutdoorHQ
*Radiosity_OutdoorLight
*Radiosity_IndoorLQ
*Radiosity_IndoorHQ
So a typical use of radiosity for a scene using rad_def.inc is...
<source lang="pov">
#include “rad_def.inc”
global_settings {
radiosity {
Rad_Settings(Radiosity_Normal,off,off)
}
}
#default {finish{ambient 0}}
</source>

==Uses==
Lighting the inside of a house using an outside lightsource.
==Specifics==
Many small things to consider here.

'''Here are some good default settings you can use that are fairly fast and yet not horrible looking.''' 
<source lang="pov">
radiosity {
pretrace_end 4/image_width
count 50
error_bound 0.8
recursion_limit 1
}
</source>
 
'''For a more realistic appearance use the following.''' 
<source lang="pov">
radiosity {
pretrace_end 2/image_width
count image_width/2
error_bound 128/image_width
recursion_limit 1
}
</source>
 
'''For good quality indoor lighting.'''
<source lang="pov">
radiosity {
brightness 3
count 100
error_bound 0.15
gray_threshold 0.0
low_error_factor 0.2
minimum_reuse 0.015
nearest_count 10
recursion_limit 5
adc_bailout 0.01
max_sample 0.5
media off
normal on
always_sample 1
pretrace_start 0.08
pretrace_end 0.01
}
</source>

==Shortcuts==
Checks and balances within the radiosity system make it unique! 
==Bugs and Work-arounds==
Sometimes radiosity can cause artifacts, one of the most common causes of artifacts is infinite radiosity rays. A good rule is to place any radiosity scene inside a large inverse sphere to avoid any ray colliding with the background or sky_sphere. 
Another potential cause of artifacts is coincident surfaces, sometimes a radiosity ray leaks through the corners of a box or between CSG seams, one work-around seems to be using a round box with a small radius instead of a box. 
Non-zero ambient values in textures emit light, this is intended, but makes textures look wrong in test renders without radiosity. So it is common to use a declared value to turn on and off lights, ambients, and radiosity, with if statements. 

==Notes==
#Radiosity is slow and requires lots of calculations. Don't turn on without time to waste.
#Radiosity usage will vary from scene to scene and taste of the artist using it.
#Radiosity is haaaaaaard...

HowTo:Use radiosity

2007-12-28T01:25:07Z

TimA: /* Specifics */

==Radiosity==
Radiosity, also known as global illumination (GI), is a process of
calculating diffuse reflecting light in a scene. To use radiosity, include a
radiosity block in the global settings. Please note that the default setting
for an empty radiosity block is very low quality, if you are unfamiliar with
the fourteen different settings that control the look and performance of
POV’s radiosity algorithm the easiest way to get started is to use the
Rad_Settings macro from rad_def.inc, followed by a boolean for normals
and a boolean for medias. The pre-sets from rad_def.inc are...
*Radiosity_Default
*Radiosity_Debug
*Radiosity_Fast
*Radiosity_Normal
*Radiosity_2Bounce
*Radiosity_Final
*Radiosity_OutdoorLQ
*Radiosity_OutdoorHQ
*Radiosity_OutdoorLight
*Radiosity_IndoorLQ
*Radiosity_IndoorHQ
So a typical use of radiosity for a scene using rad_def.inc is...
<source lang="pov">
#include “rad_def.inc”
global_settings {
radiosity {
Rad_Settings(Radiosity_Normal,off,off)
}
}
#default {finish{ambient 0}}
</source>

==Uses==
Lighting the inside of a house using an outside lightsource.
==Specifics==
Many small things to consider here.

'''Here are some good default settings you can use that are fairly fast and yet not horrible looking.''' 
<source lang="pov">
radiosity {
pretrace_end 4/image_width
count 50
error_bound 0.8
recursion_limit 1
}
</source>
 
'''For a more realistic appearance use the following.''' 
<source lang="pov">
radiosity {
pretrace_end 2/image_width
count image_width/2
error_bound 128/image_width
recursion_limit 1
}
</source>
 
'''For good quality indoor lighting.'''
<source lang="pov">
radiosity {
brightness 3
count 100
error_bound 0.15
gray_threshold 0.0
low_error_factor 0.2
minimum_reuse 0.015
nearest_count 10
recursion_limit 5
adc_bailout 0.01
max_sample 0.5
media off
normal on
always_sample 1
pretrace_start 0.08
pretrace_end 0.01
}
</source>

==Shortcuts==
Checks and balances within the radiosity system make it unique!
==Notes==
#Radiosity is slow and requires lots of calculations. Don't turn on without time to waste.
#Radiosity usage will vary from scene to scene and taste of the artist using it.
#Radiosity is haaaaaaard...

HowTo Talk:Use the plane object/Example Code

2007-12-28T00:18:36Z

TimA: HowTo Talk:Use the plane object/Example Code moved to HowTo Talk:Use the plane object over redirect

#REDIRECT [[HowTo Talk:Use the plane object]]

HowTo Talk:Use the plane object

2007-12-28T00:18:36Z

TimA: HowTo Talk:Use the plane object/Example Code moved to HowTo Talk:Use the plane object over redirect

For some reason the code block here looks like it's missing the bottom dotted edge after saving, but looks OK in preview.

''I think that is fixed with the <source> tags, seems to be ok now.'' --[[User:Reactor|Reactor]] 10:34, 27 December 2007 (UTC)

I rendered and uploaded the first plane code for an example, and added some more stuff, but I'm wondering if the organization of the article is ok? Is it better to include the source in the page or perhaps link to it? It just seems like the source takes up a massive amount of space which might make the article weird to read, so I put the full source at the end.

I was also thinking about mentioning the math behind the plane, but that seems more like a documentation thing and less of a How To thing.

--[[User:Reactor|Reactor]] 10:33, 27 December 2007 (UTC)

HowTo:Use the plane object/Example Code

2007-12-28T00:18:36Z

TimA: HowTo:Use the plane object/Example Code moved to HowTo:Use the plane object over redirect

#REDIRECT [[HowTo:Use the plane object]]

HowTo:Use the plane object

2007-12-28T00:18:36Z

TimA: HowTo:Use the plane object/Example Code moved to HowTo:Use the plane object over redirect

==The Plane==
In POV, a plane is one of the five Infinite Solid Primitives. It is a flat surface that extends infinitely in all directions (unless clipped by an object). Planes are considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a normal vector, and a float distance. The normal vector indicates the surface normal of the plane, and the distance is how far in that direction from the origin the surface begins.

===A Simple Plane===
<source lang="pov">
#include "colors.inc"
plane
{
y, -1
pigment {checker White Tan}
}
</source>

The resultant plane (a red arrow has been added to illustrate the normal vector).

[[Image:Plane-example-1.jpg|center|thumb|320px|Example #1: A simple plane.]]

This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

===Modifying a Plane===
We can use the clipped_by object modifier to render only the portion of the plane within the clipping shape. Note, though, that even though the plane is by default a solid shape, the rest of the plane does not "fill" the clipping shape: only the surface (or underside) of the plane is visible.

To have a plane "fill out" the clipping shape, we must place the plane and clipping shape inside of an intersection statement.

[[Image:Plane-example-2.jpg|center|thumb|320px|Example #2: Clipped plane vs. Intersected plane]]

In the above image, the plane section on the left is clipped by a sphere. The green and blue object on the right is an identical plane and sphere, intersected.

====Full Source for Example #2====

<source lang="pov">
#include "colors.inc"

#declare Myfinish =
finish
{
specular 0.00
roughness 1.00
ambient 0.25
}

// our ground plane:
plane
{
y, -1
// this is identical to <0,1,0>, -1

pigment
{
checker White Tan
}

finish
{
Myfinish
}
}

// plane section on the left, using clipped_by:
plane
{
y, 2

clipped_by
{
sphere{ <-3,2,0>, 2 }
}

pigment
{
checker Black Red
}

finish
{
Myfinish
}
}

// plane section on the right, using intersection:
intersection
{

plane
{
y, 2
}

sphere
{
<3,2,0>, 2
}

pigment
{
checker Blue Green
}

finish
{
Myfinish
}
}

light_source
{
<0,0,0>
color rgb <1,1,1>

translate <10,100,-100> * 10
}

camera
{
location <0,5,-12>
look_at <0,2,0>
}
</source>

HowTo Talk:Use the plane object

2007-12-28T00:17:39Z

TimA: HowTo Talk:Use the plane object moved to HowTo Talk:Use the plane object/Example Code

HowTo:Use the plane object

2007-12-28T00:17:39Z

TimA: HowTo:Use the plane object moved to HowTo:Use the plane object/Example Code

HowTo Talk:Use radiosity

2007-12-27T23:34:01Z

TimA:

A description of the parameters might be a documentation sort of thing, but seeing what changes to parameters do is sort of a How To thing...

I am working on a few demonstration scenes for the following:
#a scene demonstrating ''when'' radiosity could be used to improve realism.
#*When I was new to POV, I didn't know when to use radiosity, and I think different examples showing the difference between using the ambient light for global illumination and radiosity would be helpful in making such a determination.
#Using radiosity with lightsources
#Using radiosity without lightsources (glowing object method)
#Effects ok sky_sphere or background on radiosity
# possibly a 10 x 10 grid of images with parameter changes (and render times) to demonstrate some of the main speed/quality ratios.
#???

Input would be appreciated!
--[[User:Reactor|Reactor]] 22:32, 27 December 2007 (UTC)

It makes sense to cover the typical problems and artifacts that people run into, and how to avoid those pitfalls. 
Maybe something like a Cornell box for a test scene? 
[[User:TimA|TimA]] 23:34, 27 December 2007 (UTC)

HowTo Talk:Use radiosity

2007-12-27T23:31:11Z

TimA:

A description of the parameters might be a documentation sort of thing, but seeing what changes to parameters do is sort of a How To thing...

I am working on a few demonstration scenes for the following:
#a scene demonstrating ''when'' radiosity could be used to improve realism.
#*When I was new to POV, I didn't know when to use radiosity, and I think different examples showing the difference between using the ambient light for global illumination and radiosity would be helpful in making such a determination.
#Using radiosity with lightsources
#Using radiosity without lightsources (glowing object method)
#Effects ok sky_sphere or background on radiosity
# possibly a 10 x 10 grid of images with parameter changes (and render times) to demonstrate some of the main speed/quality ratios.
#???

Input would be appreciated!
--[[User:Reactor|Reactor]] 22:32, 27 December 2007 (UTC)

It makes sense to cover the typical problems and artifacts that people run into, and how to avoid those pitfalls.
Maybe something like a Cornell box for a test scene?

HowTo:Use radiosity

2007-12-27T10:16:32Z

TimA: /* Specifics */

HowTo:Use radiosity

2007-12-27T10:08:39Z

TimA: /* Radiosity */

HowTo Talk:Use the plane object

2007-12-27T10:06:17Z

TimA: New page: For some reason the code block here looks like it's missing the bottom dotted edge after saving, but looks OK in preview.

For some reason the code block here looks like it's missing the bottom dotted edge after saving, but looks OK in preview.

HowTo:Use the plane object

2007-12-27T10:04:04Z

TimA: /* The Plane */

==The Plane==
In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a direction vector, and a float distance. The direction vector indicates the "up" direction, and the distance is how far in that direction from the origin the surface begins.
<source lang="pov">
#include "colors.inc"
plane {y,-1
pigment {checker White Tan}
}</source>
This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

HowTo:Use the plane object

2007-12-27T09:45:14Z

TimA: /* The Plane */

==The Plane==
In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a direction vector, and a float distance. The direction vector indicates the "up" direction, and the distance is how far in that direction from the origin the surface begins.
<source lang="pov">
#include "colors.inc"
plane {y,-1
pigment {checker White Tan}
}</source> 
This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

HowTo:Use the plane object

2007-12-27T09:33:26Z

TimA: /* The Plane */

==The Plane==
In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a direction vector, and a float distance. The direction vector indicates the "up" direction, and the distance is how far in that direction from the origin the surface begins.
<source lang="pov">
#include "colors.inc"
plane {y,-1
pigment {checker White Tan}
}
</source>
This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

HowTo:Use the plane object

2007-12-26T02:49:12Z

TimA: /* The Plane */

==The Plane==
In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a direction vector, and a float distance. The direction vector indicates the "up" direction, and the distance is how far in that direction from the origin the surface begins.

#include "colors.inc"
plane {y,-1
pigment {checker White Tan}
}

This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

HowTo:Use the plane object

2007-12-26T02:48:35Z

TimA: /* The Plane */

==The Plane==
In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when you use a plane in CSG. A plane is defined in POV by a direction vector, and a float distance. The direction vector indicates the "up" direction, and the distance is how far in that direction from the origin the surface begins.
#include "colors.inc"
plane {y,-1
pigment {checker White Tan}
}
This uses the default y vector for "up", it's easy enough to rotate a plane to the desired angles after creating it, but vrotate can be used to rotate the vector before defining the plane.

HowTo:Use the plane object

2007-12-26T02:38:14Z

TimA: New page: ==The Plane== In POV a plane is considered to have a volume, any point that is "under" the plane is inside, and any point that is "above" the plane is outside. This becomes important when ...

HowTo:Use radiosity

2007-12-26T02:16:10Z

TimA: /* Radiosity */