Environment Probe
Environment Probe is a light source which also provides reflections on an object inside the probe by using a cubemap (pre-baked or dynamically changing each frame). In Unigine, Environment Probes have two types of projections:
- Box projection - works better for indoor scenes (when the room has a 3D box shape) or box-shaped outdoor scenes (back alley between buildings).
- Spherical projection - works better for all other cases (reflections on car, spherical room, etc.).
With Environment Probes you can create reflections instead of creating reflection materials.
See Also#
- The article on Using Environment Probes
- The article on Light Sources Parameters
- The LightEnvironmentProbe class to manage environment probes via API
Overview#
Environment Probe is a great thing to increase performance, decrease the number of materials and make the life of content designers easier.
Environment probes use cubemaps that were baked (or grabbed with a special tool). This cubemap will play the role of the reflection and the light simulation. Here is an example:
We have two houses with different color of the interior and put same objects (with reflection material, for example, metal) into these houses. What will happen?
If we don't speak about the dynamic reflections, you'll need to reflect the interior on each object. But interiors have different ambient color, and that is why you'll need to create 2 different materials for them. Not optimized at all.
Environment probes remove this flaw. Once you added an object, you don't think about the reflection material for it. The environment probe will map the cubemap to the object.
There is a difference in mapping cubemaps to transparent and non-transparent objects:
- If an object is transparent, the environment probe will map the cubemap only if the entire object is inside the radius of the environment probe. Otherwise, the object won't be affected by the environment probe at all.
- If an object is non-transparent, the environment probe will map the cubemap to any part of the object which is inside the radius of the probe.
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Transparent object affected by environment probe |
Non-transparent object affected by environment probe |
If you put several environment probes that affect a non-transparent object (rendered in the deferred pass) their cubemaps will be blended smoothly. Here is an example, a long corridor which has walls painted in different colors.
We put two environment probes and both of them affect the object (when the object will be in the intercrossing area). When you have large locations, you should use several environment probes instead of one to make the final image more realistic.
The SSR (Screen Space Reflections) effect makes the final image more realistic, because it appends reflections that cannot be baked into cubemaps. Using environment probes and SSR is a great method for pretty fast imitation of reflections with dynamic lighting.
Multiple Environment Probes for Transparent Objects#
The Multiple Environment Probes option set for a transparent object (rendered in the forward pass) allows several environment probes affect the object and map their cubemaps to it.
- When the option is disabled, only the last set environment probe will affect the object. At that the entire object must be inside the radius of the environment probe. Otherwise, it won't be affected by the environment probe at all.
- When the option is enabled, the object will be lit by all of the environment probes: each probe will affect the part of the object, which is inside the probe. Cubemaps of the environment probes will be blended in the intercrossing areas.
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Multiple Environment Probes is off: only the left cubemap is mapped to the object |
Multiple Environment Probes is on: both cubemaps are mapped and blended |
Adding Environment Probe#
To add an Environment Probe object to the scene via UnigineEditor, do the following:
- Run the project with UnigineEditor.
- On the Menu bar, click Create -> Lights and select the required shape of the environment probe: box or sphere. The projection shape can be changed after it is created via the Parameters window.
- Place the environment probe.
- Grab the cubemap texture for the environment probe. You can grab it via the Parameters window or use the Bake Lighting tool.
- Adjust the environment probe settings.
- You can't bake realtime lights (LightOmni, LightProj, etc.) to an environment probe. The best you can do is to place spheres with emission materials instead of lights, adjust emission intensity and then bake lighting. However, the result will look worse than you'd have with realtime lights.
- Use the Bake to Environment Probes option to define if a surface should have its reflections baked to environment probes.
When an Environment Probe is selected in the UnigineEditor viewport, reference spheres are visualized in the center of the probe:
- Reflective sphere helps in estimating the reflection provided by the probe;
- Diffused sphere helps in estimating the ambient lighting provided by the probe (requires Ambient lighting to be enabled).
Environment Probe Settings#
The environment probe settings can be found in the Node tab of the Parameters window. This tab includes both the parameters attributable to all light sources and the parameters specific for the environment probe. The specific parameters are described below.
Common Parameters#
| Projection Shape | Type of projection shape to be used by the Environment Probe:
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|---|---|
| Box Projection Size | Specifies the size of the box projection. |
| Attenuation Power | Sets the attenuation power for the light. |
| Attenuation Distance | Sets the attenuation distance for the light. |
Render Parameters#
| Color | Sets the light color in the RGBA format. The color defines both the plausibility of virtual representation and its aesthetic component. |
|---|---|
| Intensity | Sets the light color multiplier, which provides fine control over color intensity of the emitted light:
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| Shadow Mask | The shadow mask controls rendering of a shadow cast by an object lit by a light source. |
| Viewport Mask | Sets the viewport mask for the light. |
| Visibility Distance | Distance from the camera, in units, up to which the environment probe will be rendered. |
| Fade Distance | Distance from the camera, in units, starting from which the environment probe starts to fade out gradually. |
| Render Water | Renders the environment probes on water. |
| Render Transparent | Renders the environment probes on transparent object. |
| Use Sun Color | Enables the influence of sun light color on the environment probe. Notice When enabled, this option makes the environment probe color black at night, or orange at sunset. |
| Additive Blending | Enables the additive blending mode for the environment probe. This option offers more flexibility in lighting and reflections control. You can use it to blend lighting and reflections of several environment probes together and control them separately. |
Ambient Parameters#
| Enabled | Enables ambient ligting for the Environment Probe. By default, Environment Probes are used for reflections only, as for lighting, it is recommended to simulate it using Voxel Probes and Lightmaps. This approach ensures the best result, however you can still use Environment Probe for ambient lighting by enabling this option. |
|---|---|
| Global Illumination | Enables the global illumination simulation. Environment probe generates fake GI by using given cubemap. Notice This parameter is available for box projection only. |
| Contrast | Sets the contrast of ambient lighting. |
Reflection Parameters#
| Gloss Corners | Sets the intensity of reflection gloss near the box projection corners. Notice This parameter is available for box projection only. |
|---|---|
| Parallax |
Parallax correction enables rendering of reflections taking into account the camera's position. When this option is disabled, reflection cubemaps are simply projected onto objects, and do not follow the viewer's perspective.
Notice
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Baking Settings#
| Dynamic | Specifies if the reflection is dynamic. Notice The Dynamic Reflections option should be enabled: Rendering -> Features -> Dynamic Reflections. |
|---|---|
| Correct Roughness | Enables one of correction modes for environment probe reflections on rough surfaces or disables correction. Available modes are Low, Medium, High, and Ultra — they differ in the number of rays used to create a reflection on a rough surface. Notice Available for dynamic mode only. |
| Faces Per Frame | Cubemap update interval. Notice
Available for dynamic mode only.
|
| Grab by Bake Lighting | Specifies if the cubemap texture is to be modified by the Bake Lighting Tool. |
| Reflection Viewport Mask | The mask that controls rendering of the environment probe's reflections into the reflection camera viewport. |
| Resolution | Resolution of the reflection texture, in pixels. Notice Setting too high resolution on a low-performance GPU with low memory capacity may cause engine crash. |
| Supersampling | Number of samples per pixel used for image grabbing supersampling. |
| Mipmaps Quality | Quality of mipmaps. Notice Setting too high quality on a low-performance GPU with low memory capacity may cause engine crash. |
| Near Clipping | Distance to near clipping plane for image grabbing. |
| Far Clipping | Distance to far clipping plane for image grabbing.
Notice
An extremely big difference between the Near and Far Clipping Planes can cause baking the space into black. Therefore, if the required Far Clipping Plane value is outside the range, adjust the Near Clipping value proportionately. |
| Sky Cutout | Cut out sky rendering in the environment probe and renders dynamic reflection instead of the sky. Notice This parameter can be used to render changes of the sky gradient in a window, when the time of the day changes. |
| Local Space | Enable local space (local coordinates) for environment probes. Can be used for scenes with moving objects. Notice It is recommended to use this parameter, if you plan to rotate the environment probe after baking. |
Notice You can use the following 7 visibility options together with additive blending to provide more flexibility in light baking. Thus, you can make environment probes independent of each other and combine them to produce some sort of dynamic GI effect. |
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| Visibility Sky | Enables baking of lighting from the sky to the environment probe. |
| Visibility Light World | Enables baking of world light sources to the environment probe. |
| Visibility Light Omni | Enables baking of omni light sources to the environment probe. |
| Visibility Light Proj | Enables baking of projected light sources to the environment probe. |
| Visibility Voxel Probe | Enables baking of other voxel probe light sources to the environment probe. |
| Visibility Emission | Enables baking of emission light sources to the environment probe. |
| Visibility Lightmap | Enables baking of lightmapped surfaces to the environment probe. |
| Texture | Cubemap texture for reflection.
Notice
Every bake lighting procedure makes changes to the asset selected in this field when the Grab by Bake Lighting mode is enabled. You can leave the field empty to avoid losing content. In this case a new generated lighting texture will be set for this parameter after the bake lighting procedure. Generated textures are stored in the data/bake_lighting folder. |
| Cutout By Shadow | Enables clipping of reflections occluded by obstacles (located in shadowed areas relative to the light source). This feature uses the depth texture grabbed for the environment probe to determine reflections that should be visible.
Notice
When enabled the three parameters listed below (Bias, Normal bias, and Depth Texture) are available.
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| Bias | Bias that is used to correct inexact shadowing of the scene objects for the Cutout By Shadow feature. It controls the depth offset added to the current depth value stored in the shadow map. Similar to Bias parameter for shadows. |
| Normal bias | Bias obtained for the Cutout By Shadow feature by shifting the surface on which the shadow falls. The surface is shifted along normals stored in the normal map. Similar to Normal Bias parameter for shadows. |
| Depth Texture | Depth texture used for clipping reflections occluded by obstacles. Notice
This texture is static and requires re-generation each time the position or size of the environment probe are changed. To grab the depth texture for clipping perform the following steps:
Notice
Every bake lighting procedure makes changes to the asset selected in this field when the Grab by Bake Lighting mode together with the Cutout By Shadow mode are enabled. You can leave the field empty to avoid losing content. In this case a new generated depth texture will be set for this parameter after the bake lighting procedure. Generated textures are stored in the data/bake_lighting folder. |
