Light Sources Parameters

This article contains parameters common for the omni-directional light source, projected light source, environment probes, voxel probes, and world light source. Each light source has unique parameters, described in the corresponding articles. Note that not all the parameters described in this article are available for each type of the light source.

Common Settings#

Mode

Light's mode that defines rendering of the light source. It also affects rendering of shadows from the light source, and defines the impact of the light source on the light baking process.

Dynamic — the light source provides direct real-time lighting only. It is turned off while light baking is being calculated. Only dynamic shadows are rendered.
Static — the light source contributes to light baking and remains enabled all the time providing the direct real-time lighting. This option can cause lack of physical accuracy registered by the eye. Shadow types rendered in this case are defined by the Shadow Mode (or Shadow Cascade Mode for World Lights).

Shadow Mask

The shadow mask controls rendering of a shadow cast by an object lit by the light source.

Viewport Mask

For the light to be rendered, its viewport mask should match the camera's viewport mask.

Color Mode

Color calculation mode for the light source. The following mode are available:

Classic mode. The light source color is defined by the Color value.
Temperature mode. The light source color is defined by the color temperature and color filter values.

Color

Color of the light in the RGBA format. By default, the light is white.

Color Filter

Color multiplier for the light source color (calculated using the color temperature value). This can be used to imitate colored glass. The parameter is available only when the Temperature color mode is set.

Temperature

Light source temperature used for light color calculation. The maximum value is 40000.


Temperature = 1000	Temperature = 40000

Intensity

Multiplier for the light color used to control color intensity. The higher the value, the brighter the light is.

The minimum value of 1 corresponds to the least saturated light color.
The maximum value of 100 equals the most bright and intense color.


Intensity = 7	Intensity = 12

Lux

Intensity of the light color (as perceived by the human eye) in lux. In UNIGINE, all light sources have the intensity of 1 by default, which is equal to 100000 lux.

Attenuation Settings#

Power

Light attenuation power used to simulate light intensity gradual fading. This parameter determines how fast the intensity decreases up to the attenuation distance set for the light source.

If the attenuation power is set to 0 or close to it, the edge between illuminated and non-illuminated areas will be sharp.
Increasing the value up to the maximum of 1 will render softly dispersed light at the non-illuminated areas border.

LightOmni power = 0.001

LightOmni power = 0.5

LightOmni power = 1

LightProj power = 0.001

LightProj power = 0.5

LightProj power = 1

Distance

Distance from the light source shape, at which the light source doesn't illuminate anything. In other words, this parameter determines the size of the area illuminated by the light source.


Distance = 1	Distance = 1.5

Shape Settings#

Type

Shape of the light source. The following shapes are available:


Point shape	Sphere shape

Capsule shape	Rectangle shape

By using this parameter, you can create an area light that illuminates objects in different directions at once. Also a light source of each shape provides a physically correct speck on illuminated surfaces.

NoticeA light source of the rectangular shape produces the light and the speck in a form of a rounded rectangle.

Radius

Radius of the spherical, capsule-shaped or rectangular light source.

Length

Length of the capsule-shaped or rectangular light source.

Height

Height of the rectangular light source.

Distance Visibility Settings#

Light	Distance at which the light source starts fading. If the distance is set to inf, the source is always rendered.
Shadow	Distance up to which the casted shadows completely fade out.
Fade	Distance at which the light gradually disappears. This parameter enables to render the light with decreasing radiance after the Light distance is past.

Rendering Settings#

Water	Indicates whether to render the light source on the water surface or not.
Transparent	Indicates whether to render the light source on the transparent surfaces or not.

Notice

Shadow settings described in this section are common for the omni-directional and projected light sources. Shadow settings for the world light source are described in the corresponding article.

Enabled

Toggles rendering of shadows from the light source on and off.

Shadows from omni light enabled (the left cube) and disabled (the right cube)

Mode

Is available when the static light mode is enabled.Two shadow modes are available:

Mixed. Shadows from surfaces with both mixed and dynamic shadow mode enabled are rendered as follows: the dynamic shadow map is copied into the static depth texture and the result is rendered.
Static. Only shadows from surfaces with the mixed shadow mode enabled are rendered. These shadows are stored in the depth texture.

For fine-tuning static light and shadows, see the optimization recommendations.

Depth Texture

The R32F texture that stores the shadow map: a 2D texture array for the Omni light source, or a 2D texture for the Projected light source.

Resolution

Size of the shadow map that defines the shadow quality.

The higher the resolution, the smoother and true to life the result is.
The lower the resolution, the more blocky and jagged the shadow outline appears.


Shadow resolution = 64	Shadow resolution = 512

Notice

A shadow map is a 32-bit texture (in case of Omni light, it's a 2D texture array ), and higher resolution significantly increases memory consumption. Moreover, heavy 4K shadow maps for lights with mixed shadow mode enabled may significantly affect performance due to blending of baked and dynamicshadow maps.

Bias

Shadow bias that is used to correct inexact shadowing of the scene objects. It controls the depth offset added to the current depth value stored in the shadow map. Such offset is adaptively calculated with respect to the slope angle of the light source, its resolution and also the distance to the light source at shadow map applying

If the shadow acne appears, the bias value should be increased. This procedure eliminates the self-shadowing effect, as the points will appear closer to light source when compared to the map depth value.
If the bias value is set too high, the shadow will look detached from the object casting it (see the 3rd picture below).

Bias = 0; Normal bias = 1

Bias = 4; Normal bias = 1

Bias = 30; Normal bias = 1

Normal bias

Shadow bias that is achieved by shifting the surface on which the shadow falls. The surface is shifted along normals stored in the normal map.


Normal bias = 0; Bias = 1	Normal bias = 2; Bias = 1

Depending on the normal map of the surface, the shadow may differ for the same values of Normal bias.


Normal bias = 2	Normal bias = 2

Softness

Size of the blur applied to the shadow edge.

Low softness values corresponds to the crisp and sharp shadow edges.
Higher softness values serve to accentuate the effect of soft indirect lighting.


Softness = 0	Softness = 1

Enabled

Enables or disables screen space shadows from the light source.

Screen Space Shadows from omni light on (the left cube) and off (the right cube). Shadows are disabled.

Number of Rays

Number of rays used in screen space ray tracing. The higher the number of rays, the more the computation of pixel shading is accurate.


Number of Rays = 1	Number of Rays = 15

Number of Steps

Number of steps each ray traces. The higher the number of steps, the more the computation of pixel shading is accurate.


Number of Steps = 4; Number of Rays = 1	Number of Steps = 32; Number of Rays = 1

Noise Ray

Ray tracing dispersion. The higher the noise, the more the direction of rays is chaotic.


Noise Ray = 0.5	Noise Ray = 0

Noise Step

Dispersion of steps. The higher the noise, the more the steps are scattering.


Noise Step = 0.5; Noise Ray = 0.5	Noise Step = 0; Noise Ray = 0.5

Depending on the value of the Noise Ray parameter, the shadow may differ for the same values of Noise Step.


Noise Step = 0.5; Noise Ray = 0	Noise Step = 0; Noise Ray = 0

Step Size

Length of each step used in ray traced shadows.

Low values cause the closest pixels to shade.
Higher values lengthen the shadow spreading.
Too high values can provoke shadow gaps.


Step Size = 0.5	Step Size = 20

Threshold

Limit of samples passing the screen space shadowing.

Low values let pass more samples which causes the shading of inappropriate pixels.
Higher values can also cause inaccurate shading by limiting appropriate samples.

Threshold = 0

Threshold = 1

Threshold = 4

Softness

Size of the blur applied to the shadow edge.

Low softness values corresponds to the crisp and sharp shadow edges.
Higher softness values serve to accentuate the effect of soft indirect lighting.


Softness = 0	Softness = 0.5

Noise Translucent

Makes translucent shadows smoother by adding noise. The higher the value the more intense and noticeable the noise is.

NoticeThis option affects performance, so use it only in case it noticeably improves the result.

View Bias

This parameter can be used to create an effect of fuzziness for vegetation (e.g. leaves of saintpaulia).

Lens Flares simulate the effect of lights refracting inside camera lens. They are used to represent very bright lights or to add more atmosphere to your scene. The settings described below are used per-light, you can also use the lens flares camera effect, which is applied to all lights and bright objects (e.g. having an emissive material with high intensity assigned).

Lens Flares are rendered as billboards, each associated with a part of a single texture and having a set of parameters, that determine its appearance and behavior. So, you can customize and fine tune your lens flares to fit your needs.

Notice

This feature is available only for: Omni Lights, Projected Lights and World Lights.

Enabled

Enables or disables lens flares from the light source. By default this effect is disabled.

NoticeThe maximum number of lights on the scene for which the per-light flares will be rendered is 32.

Texture

A texture used to render billboards representing lens flares. The default texture is shown in the image below. For each billboard you can specify UV coordinates within this texture to determine its appearance. You can set your own texture, that contains the appearance for all the billboards to be used.

Occlusion Fade

Lens flare occlusion fade value for the cases when the light source becomes occluded by an object. By the value of 0.0f, lens flares disappear abruptly, as the light source becomes occluded by an object. If 1.0f is set, lens flares will fade out gradually.

NoticeTransparent objects are currently treated as opaque ones (i.e. they won't occlude flares).

Occlusion Fade Border

Lens flare occlusion fade value for the cases when the light source becomes occluded by the edges of the screen. By the value of 0.0f, lens flares disappear abruptly, as the light source becomes occluded by the edges of the screen. If 1.0f is set, lens flares will fade out gradually.

Position Offset

An offset of the center of lens flares from the world position of the light source.

Notice

This parameter is not available for World Lights


Position Offset = (0.0, 0.0, 0.0)	Position Offset = (2.0, -3.0, 0.0)

Use Light Color

When enabled, the lens flares will have the same color as the light source.

Lens Flares Billboards Settings#

Each flare is represented by a separate billboard, The default number of billboards is 30, but you can change it if necessary by adding, removing, or cloning selected billboards in the list via the corresponding buttons.

As you select a billboard in the list, its parameters become available for editing in the fields below.

NoticeYou can enable visualization of lens flare billboards via Helpers -> Show Wireframe.

Color

Color multiplier for the selected billboard. Texture colors will be multiplied by this value. By default the color is white.

Size

This parameter controls the size of the selected billboard.


Size = 1.5	Size = 5

Intensity

Multiplier for the billboard color used to control color intensity. The higher the value, the brighter the billboard is.


Intensity = 1	Intensity = 5

Offset

Offset determines the distance between the light source and the billboard along the vector oriented from the light source to the screen center. The lower the absolute value is, the closer to the light source the billboard will be. Negative values indicate that the distance is measured in the opposite direction.


Offset = 0.3	Offset = 0.9

Offset Scale

Determines how the billboard changes its scale depending on the distance from the light source. As the offset from the light source increases:

values less than 1.0f will make the billboard shrink.
values greater than 1.0f will make the billboard grow.


Offset Scale= 1.0	Offset Scale = 4.0

Lower Left X

X-coordinate of the lower left corner of the selected billboard in the lens flares texture, in the range [0.0, 1.0], e.g., the value equal to 0.5 corresponds to the middle of the texture.

Lower Left Y

Y-coordinate of the lower left corner of the selected billboard in the lens flares texture, in the range [0.0, 1.0], e.g., the value equal to 0.5 corresponds to the middle of the texture.

Upper Right X

X-coordinate of the upper right corner of the selected billboard in the lens flares texture, in the range [0.0, 1.0], e.g., the value equal to 0.5 corresponds to the middle of the texture.

Upper Right Y

Y-coordinate of the upper right corner of the selected billboard in the lens flares texture, in the range [0.0, 1.0], e.g., the value equal to 0.5 corresponds to the middle of the texture.

Rotate

Enables or disables rotation of the lens flare billboard. When enabled the top of the billboard will always face the center of the screen.

Chapters:

Light Settings#

Common Settings#

Attenuation Settings#

Shape Settings#

Distance Visibility Settings#

Rendering Settings#

Shadow Settings#

Screen Space Shadow Settings#

Lens Flares Settings#

Lens Flares Billboards Settings#