Sensors in expert mode
Sensors in expert mode
Embedded Files
Integrator settings
Integrator settings
The integrator is a global illumination algorithm used to solve the light transport equation :
Its name comes from the high dimension integral of the equation the algorithm must solve. Predictive Engine provides a Path Tracing integrator at the moment. If the expert mode is enabled, its settings are editable in the UVR Camera Settings component and are defined as follow :
The Variant defines which variant is used for the path tracer : the Multiple Importance Sampling or the Brute Force variant. The Brute Force variant has a slower convergence than the MIS.
The Max Depth is the maximum number of bounces allowed for a path. A small value speeds up the rendering but will introduce a lot of bias.
Default value: 1024.
Accepted values: [1; 1024].
The Thread Pool Size is the number of threads alive at each iteration. A low value reduces the memory consumption of the algorithm at the expense of the performance.
Default value: 1,000,000.
Accepted values: [16,384; 4,194,304], depending on the memory capacity of your GPU.
The Minimum Render Time is the minimum time (in milliseconds) before a visual feedback is displayed on screen. If this time is too low, the feedback image will be incomplete and noisy. If it is too high, the feedback will be less interactive.
The Mollifier Enabled toggle defines whether the mollifier defined on specular materials (see section above) should be enabled or ignored. Default value: true.
Radiometric sensor central wavelength
Radiometric sensor central wavelength
If the expert mode is enabled, you can specify how the radiometric sensor channels are computed.
The "Use central wavelength" toggle defines whether the channels are centered on their definition wavelength (the channel at 380nm goes from 360nm to 400nm) or they start at their definition wavelength (the channel at 380nm goes from 380nm to 420nm).
The "Use central wavelength" toggle is set to true by default.
Custom sensor
Custom sensor
When the expert mode is enabled, a new custom sensor type is available.
The custom sensor enables you to choose precisely which channels are computed by Predictive Engine. A channel is defined by a spectrum -- its integration curve -- that determine how much light is detected by the sensor at each wavelength. For instance, a photographic sensor has three channels (one for each pixel type : R, G or B) defined by the pixel integration curve.
Some preset channels are available to create automatically photographic, photometric or radiometric sensor channels :
the photographic preset creates three RGB channels defined by the given preset spectrums,
the photometric preset creates three XYZ channels defined by the given preset spectrums
the radiometric preset creates n (n = number of bands) constant channels defined regularly on the given spectrum range.
The channels can also be defined manually with a name and a custom spectrum.
A custom channel should never have the same name as a preset channel ("R","G","B" for the photographic channels, "X","Y","Z" for the photometric channels).
Custom post pipeline
Custom post pipeline
When using a custom sensor, you can define manually the output of the Predictive Engine renderer.
Three types of color systems are available :
RGB : the output is defined by the three given XYZ channels, the raw image is then converted to LDR RGB using a given gamut, a gamma correction is applied.
If the photometric preset is used on the sensor, the channels can be defined by the default Photometric XYZ channels.
Otherwise, the channels are selected among the available layers (see section bellow) and channels defined on the sensor.
Raw : the output is defined by the three given RGB channels, the raw image is only processed with a gamma correction.
If the photographic preset is used on the sensor, the channels can be defined by the default Photographic RGB channels.
Otherwise, the channels are selected among the available layers (see section bellow) and channels defined on the sensor.
False Color : one of the sensor channels is visualized as a representation of the measured physical quantity in false colors. It is also possible to display :
the normals/tangents/bi-tangents of the scene : each vector (x,y,z) is represented as a color (r,g,b),
the material : each ID is represented by a color, the color are regularly selected in the given colormap,
the depth : the distance between the camera and the elements in the scene is displayed using the given colormap.
Layer selection
Layer selection
In addition to path tracing outputs, Predictive Engine can also compute some characteristics of the scene : normals, tangents, bi-tangents, depth, material IDs, and the four components of the Stokes vector (polarization definition).
When saving the raw Predictive Engine output (see the Outputs section), each characteristic is saved in a specific layer and can be found in the *.exr file.
By default, Predictive Engine computes all the layers of the scene. If the expert mode is enabled, you can disable some of the layers. Disabling layers does not have much impact on performance.
Custom gamuts in Color Systems
Custom gamuts in Color Systems
The output of the Predictive Engine renderer is a raw image containing XYZ values. The XYZ image is then converted to an RGB image. The conversion takes into account the subset of colors which can be accurately represented by the output device : the gamut.
The gamut is defined by four points given in the CIE 1931 chromaticity diagram format : see image on the right. In this example, the colored triangle is the gamut available to the sRGB color space, typically used in computed monitors.
Some default gamuts are always available in the Color System definition. If the Expert Mode is enabled, you can also define a custom gamut with points in the CIE 1931 chromaticity diagram.
Figure A : sRGB gamut in the CIE 1931 chromaticity diagram format.
https://fr.wikipedia.org/wiki/Gamut
Custom settings for the denoiser
Custom settings for the denoiser
The denoiser is a tool to reduce the noise in the generated images. When the Expert Mode is disabled, the denoiser uses default settings. When it is enabled, you can define the following settings :
Maximum Memory to Use is the memory allocated to the denoiser in megabytes. A high value will increase the performance at the expense of the memory consumption.
Default value: 256.
Dataset defines whether the HDR or LDR OptiX dataset is used to denoise the image.
Default value: true.
Blend Denoised-Original is a blending factor between the denoised output and the original input.
Default value: 0.05.
Acceptable values: [0 (= denoised), 1 (= original input)].
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