# World¶

Éclairage avec une image HDR.

The world buttons let you set up the shading of your scene in general. It can provide ambient color, and special effects such as mist, but a very common use of a World is to shade a background color. These are accessible via the World tab. The world environment can emit light, ranging from a single solid color, physical sky model, to arbitrary textures.

World

## Surface¶

Référence

Panneau

World ‣ Surface

The surface shader defines the light emission from the environment into the scene. The world surface is rendered as if it is very distant from the scene, and as such there is no two-way interacting between objects in the scene and the environment, only light coming in. The only shader accepted is the Background node with a color input and strength factor for the intensity of the light.

### Image Based Lighting¶

For image based lighting, use the Environment Texture node rather than the Image Texture node for correct mapping. This supports Equirectangular (also known as Lat/Long) for environment maps, and Mirror Ball mapping for converting photos of mirror balls to environment maps.

## Volume¶

Référence

Panneau

Panneau : World ‣ Volume

A volume shader can be applied to the entirely world, filling the entire space.

Currently this is most useful for night time or other dark scenes, as the world surface shader or sun lamps will have no effect if a volume shader is used. This is because the world background is assumed to be infinitely far away, which is accurate enough for the sun for example. However, for modeling effects such as fog or atmospheric scattering, it is not a good assumption that the volume fills the entire space, as most of the distance between the sun and the earth is empty space. For such effects it is be better to create a volume object surrounding the scene. The size of this object will determine how much light is scattered or absorbed.

## Ambient Occlusion¶

Référence

Panneau

World ‣ Ambient Occlusion

Ambient occlusion is a lighting method based on how much a point on a surface is occluded by nearby surfaces. It simulates soft global illumination shadows by faking darkness perceived in corners and at mesh intersections, creases, and cracks, where ambient light is occluded, or blocked. This is a trick that is not physically accurate, but it is useful to emphasize the shapes of surfaces, or as a cheap way to get an effect that looks a bit like indirect lighting.

Factor

The strength of the ambient occlusion; value 1.0 is like a white world shader.

Distance

Distance from shading point to trace rays. A shorter distance emphasizes nearby features, while longer distances make it also take objects farther away into account.

Lighting from ambient occlusion is only applied to diffuse reflection BSDFs; glossy or transmission BSDFs are not affected. Transparency of surfaces will be taken into account, i.e. a half-transparent surface will only half occlude.

Une méthode alternative à l’occlusion ambiante sur une base est d’utiliser le shader Ambient Occlusion.

## Mist Pass¶

Référence

Panneau

Panneau : World ‣ Mist Pass

Mist example (blend-file).

Mist can greatly enhance the illusion of depth in your rendering. To create mist, Blender makes objects farther away more transparent (decreasing their Alpha value) so that they mix more of the background color with the object color. With Mist enabled the further the object is away from the camera the less its alpha value will be.

Affiché quand Mist pass est activé. Les valeurs de Mist se trouvent entre 0.0 et 1.0 et sont disponibles dans le node Render Layers.

Start

The distance from the camera at which the mist starts to fade in.

Depth

The distance from Start of the mist, that it fades in over. Objects further from the camera than Start + Depth are completely hidden by the mist.

Falloff

The curve function that controls the rate of change of the mist’s strength further and further into the distance.

Utilise le même calcul que l’atténuation de lumière ($$1\over{x^2}$$) et offre la transition la plus lisse de transparent (0.0) à opaque (1.0).

Linear

A un début plus accentué que quadratic ($$1\over{x}$$).

A le début le plus accentué ($$1\over{\sqrt{x}}$$) et s’approche de 1.0 plus rapidement que les deux autres fonctions.

Astuce

Une visualisation peut être activée dans le panneau Camera ‣ Display.

Astuce

Because Mist works by adjusting transparency, this can sometimes cause objects to be partially transparent when they should not be. One workaround is to set the Mist settings as desired, but turn Mist off. The Mist data is still available for compositing even though it is off. Use Compositing to feed the Mist pass to the Alpha Over node to blend the background color (or a render layer with just the sky) with the rendered image. This produces the mist effect but since Mist is off the object transparency (or lack of) is preserved.

## Settings¶

Référence

Panneau

World ‣ Settings

### Surface¶

Multiple Importance Sample

Enabling this will sample the background texture such that lighter parts are favored, creating an importance map. It will producing less noise in the render in trade of artifacts (fireflies). It is almost always a good idea to enable this when using an image texture to light the scene, otherwise noise can take a very long time to converge.

Ci dessous se trouve une comparaison entre Multiple Importance Sample off et on. Les deux images sont rendues pendant 25 secondes (Off: 1500 échantillons, On: 1000 échantillons).

 Multiple Importance Sample off.¶ Multiple Importance Sample on.¶
Map Resolution

Sets the resolution of the importance map. A higher resolution will better detect small features in the map and give more accurate sampling. but conversely will take up more memory and render slightly slower. Higher values also may produce less noise when using high-res images.

Max Bounces

Nombre maximal de bonds avec lequel la lumière d’arrière-fond va contribuer au rendu.

Voir aussi

Consultez Réduction de bruit pour plus d’informations sur la manière de réduire le bruit.

### Volume¶

Sampling Method
Distance

Si vous avez un volume plutôt dense qui est posé loin alors l’échantillonnage Distance est habituellement plus efficace.

Equiangular

Si vous avez une lumière à l’intérieur ou près du volume alors l’échantillonnage équiangular est meilleur.

Multiple Importance

Si vous avez une combinaison des deux, alors l’échantillonnage multiple importance sera meilleur.

Interpolation

Méthode d’interpolation à utiliser pour le volume.

Linear

Good smoothness and speed.

Cubic

Interpolation de haute qualité lissée, mais plus lente.

Homogeneous Volume

Assume volume has the same density everywhere (not using any textures), for faster rendering. For example absorption in a glass object would typically not have any textures, and by knowing this we can avoid taking small steps to sample the volume shader.

## Ray Visibility (visibilité du rayon)¶

Référence

Panneau

World ‣ Ray Visibility

Comme avec d’autres objets, Ray Visibility vous permet de contrôler les autres shaders qui peuvent « voir » l’environnement.

### Astuces¶

Parfois il peut être utile d’avoir un arrière-plan différent qui est directement visible versus celui qui éclaire indirectement les objets. Une simple solution à cela est d’ajouter un node Mix. avec le facteur Blend défini à Is Camera Ray. La première couleur d’entrée est alors le couleur indirecte, et la seconde la couleur directement visible. C’est utile quand on utilise une image de haute résolution pour l’arrière-plan et une image en basse résolution pour l’éclairage réelle.

De même, l’ajout de rayons Is Camera et Is Glossy signifiera que l’image à haute résolution sera aussi visible dans les réflexions.

Nodes pour l’astuce ci-dessus.