Dynamic Range Optimization - Light Metering - Sky Texture
Posted: Thu Dec 25, 2014 12:11 pm
I summarize four different cases in this thread that are dealing with the same challenge:
Controlling brightness and contrast of scene objects
- Dynamic Range Optimization
- Light Metering Mode
- Controlling the brightness of Sky Textures
- Prevent scene objects from receiving light
Update / Edit:
Added information about Light Metering Modes
- - -
Dynamic Range Optimization
How do you create a light balance between the background of the Daylight Environment and an indoor environment?
Issue:
Either the default daylight environment or a "Sky texture" that is assigned are completly blown out into white.
OR
The interior is too dark without any objects being visible.
- - -
For scenes created with the "daylight environment" it would help if more options were available to deal with brightness and contrast:
Dynamic Range Optimization:
In photography it has become more and more standard to include Dynamic Range Optimization.
Basically the camera creates multiple images at different exposure steps and then combines them to create a more balanced image in relation to contrast and overall brightness.
How do you currently simulate this in OctaneRender?
- - -
Light Metering Mode
Directly related to this are options that would give more control how the light in the scene is measured and brightness and contrast levels are defined.
Spot
The user is able to click on a specific point in the scene that is used by the render engine as a reference point to calculate brightness and contrast levels.
This gives he user the option to shift preferences to specific objects in the scene that need to have optimal light conditions.
This will yield dramatic results based on the reference point choosen.
Example: The user selects an indoor object. Light metering will be based on the selected object. Any other objects in the scene may still be too dark or too bright. In this case extreme contrast and brightness differences are wanted by the user.
Center
The light is measured based on the center of the frame.
The user is looking for a more balanced light situation based on the center of the frame.
Extreme brightness and contrast differences at the edge of the frame like a sky texture may be ignored.
Multi
The light is measured across the whole frame.
The user is looking for a light situation that balances all fields of the frame equaly. Brightness and contrast is optimized across the whole frame.
- - -
- - -
Controlling the brightness of Sky Textures
Sky Texture should not be affected by lights
As far as I understand it currently there are only options for "Gamma" and "Power" to control the brightness of the Sky Texture.
Nevertheless those options do not seem enough to keep the Sky Texture visible.ยจ
In quite many light situations the sky texture is blown out white.
What currently seems to be missing is the option to have the Sky Texture not being affected by any light in the scene and especially the sun light itself.
- - -
To make more use of the sky texture the following features would seem useful
- the sky texture emitts light on objects in the scene (toggle on / off)
- the sky texture is visible in reflections (toggle on / off)
- the sky texture is not receiving any light (toggle on / off)
- - -
Prevent scene objects from receiving light
To prevent an object from receiving any light could also be a very interesting addition to the Object Layer Node.
When adding background image planes toggeling off Shadow visiblity is allready an important first step.
But the image plane is still affected by the light from the environment.
Example 1:
Add an image with a forest scenery on an image plane in the background
You may want to set the following options:
- The 2D forest background plane does not cast any shadows (possible with Object Layer node - toggle of shadow visiblity)
- The 2D forest background plane shows up in reflections (currently default)
- The 2D forest background plane is not affected by any lights in the scene
(As far as I know currently not possible. If the sun is shining from the front the background plane may be to bright. If the sun is shining from the back the background plane may be too dark.)
Example 2:
Add a 2d smoke or explosion texture on an image plane.
You may want to set the following options:
- The 2D smoke does not cast any shadows (possible with Object Layer node - toggle of shadow visiblity)
- The 2D smoke does show up in reflections (currently default)
- The 2D smoke is not affected by any lights in the scene (as far as I know currently not possible)
An option to control which objects are affected by scene lights would offer a lot of new creative possibilities how to composite 2d images and 2d special effects with 3D objects in a 3D scene
- - -
- - -
Are any of the mentioned options allready being developed?
Or are those features that can be achieved with CPU based render engines but are very difficult to be integrated in GPU rendering?
Controlling brightness and contrast of scene objects
- Dynamic Range Optimization
- Light Metering Mode
- Controlling the brightness of Sky Textures
- Prevent scene objects from receiving light
Update / Edit:
Added information about Light Metering Modes
- - -
Dynamic Range Optimization
How do you create a light balance between the background of the Daylight Environment and an indoor environment?
Issue:
Either the default daylight environment or a "Sky texture" that is assigned are completly blown out into white.
The interior is too dark without any objects being visible.
- - -
For scenes created with the "daylight environment" it would help if more options were available to deal with brightness and contrast:
Dynamic Range Optimization:
In photography it has become more and more standard to include Dynamic Range Optimization.
Basically the camera creates multiple images at different exposure steps and then combines them to create a more balanced image in relation to contrast and overall brightness.
How do you currently simulate this in OctaneRender?
- - -
Light Metering Mode
Directly related to this are options that would give more control how the light in the scene is measured and brightness and contrast levels are defined.
Spot
The user is able to click on a specific point in the scene that is used by the render engine as a reference point to calculate brightness and contrast levels.
This gives he user the option to shift preferences to specific objects in the scene that need to have optimal light conditions.
This will yield dramatic results based on the reference point choosen.
Example: The user selects an indoor object. Light metering will be based on the selected object. Any other objects in the scene may still be too dark or too bright. In this case extreme contrast and brightness differences are wanted by the user.
Center
The light is measured based on the center of the frame.
The user is looking for a more balanced light situation based on the center of the frame.
Extreme brightness and contrast differences at the edge of the frame like a sky texture may be ignored.
Multi
The light is measured across the whole frame.
The user is looking for a light situation that balances all fields of the frame equaly. Brightness and contrast is optimized across the whole frame.
- - -
- - -
Controlling the brightness of Sky Textures
Sky Texture should not be affected by lights
As far as I understand it currently there are only options for "Gamma" and "Power" to control the brightness of the Sky Texture.
Nevertheless those options do not seem enough to keep the Sky Texture visible.ยจ
In quite many light situations the sky texture is blown out white.
What currently seems to be missing is the option to have the Sky Texture not being affected by any light in the scene and especially the sun light itself.
- - -
To make more use of the sky texture the following features would seem useful
- the sky texture emitts light on objects in the scene (toggle on / off)
- the sky texture is visible in reflections (toggle on / off)
- the sky texture is not receiving any light (toggle on / off)
- - -
Prevent scene objects from receiving light
To prevent an object from receiving any light could also be a very interesting addition to the Object Layer Node.
When adding background image planes toggeling off Shadow visiblity is allready an important first step.
But the image plane is still affected by the light from the environment.
Example 1:
Add an image with a forest scenery on an image plane in the background
You may want to set the following options:
- The 2D forest background plane does not cast any shadows (possible with Object Layer node - toggle of shadow visiblity)
- The 2D forest background plane shows up in reflections (currently default)
- The 2D forest background plane is not affected by any lights in the scene
(As far as I know currently not possible. If the sun is shining from the front the background plane may be to bright. If the sun is shining from the back the background plane may be too dark.)
Example 2:
Add a 2d smoke or explosion texture on an image plane.
You may want to set the following options:
- The 2D smoke does not cast any shadows (possible with Object Layer node - toggle of shadow visiblity)
- The 2D smoke does show up in reflections (currently default)
- The 2D smoke is not affected by any lights in the scene (as far as I know currently not possible)
An option to control which objects are affected by scene lights would offer a lot of new creative possibilities how to composite 2d images and 2d special effects with 3D objects in a 3D scene
- - -
- - -
Are any of the mentioned options allready being developed?
Or are those features that can be achieved with CPU based render engines but are very difficult to be integrated in GPU rendering?