Sun light (Sun and Sky)

V-Ray simulates sun and sky light thanks to the VRaySun and VRaySky parameters, which are strictly connected.

For a deeper knowledge of VRaySun and VRaySky, you can connect to the official reference from V-Ray manufacturer: http://help.chaosgroup.com/vray/help/150SP1/vraysun_sky_param.htm

If you want to open the sun light mask, click on the Ribbon command Natural Light available in the Virtual Navigation group. You can find it both in the Layout window and in the Navigation window (Navigation group). Open this article to see how to set the background.

In the next image you can see this mask.

Sun light section

Activate: this flag allows you to enable/disable the sun light. If disabled, the rendered image will be illuminated by the sky only, which is an indirect illumination coming from the outside. We suggest you to disable the sun light only in case of an indoor room without any hole/window; in this situation, in fact, sun light will never enter the room and affect the image, but it will keep slowing down the rendering process as the engine will have to consider it too, even if useless. For this purpose, select the button Night time pre-set, that sets up the needed effects for you.
Indeed, we warmly encourage you using the sun light as it enhances tiles and objects materials and surfaces so that the final image will be better rather than if illuminated by artificial lights only. Sometimes, well … very often for medium and small rooms, it is also possible not to place any artificial light, as the sun light will be enough. Keep in mind that expert designers are used to create temporary hole(s) in some walls, which are not visible in the rendering, just in order to let the sun light entering the scene and make the illumination. Indeed, if the room already contains a window or an opened door, you do not have to create any additional hole as the sun light will enter the room and overcome the sky light.

Multiplier (0.1 - 10): this parameter gives you the idea of the light intensity. Default value is 1. You can change this parameter in case you want to reduce/increase the sun light power. Try to change it slightly, and launch a small render sample in order to understand if you have found the correct setup. (Do not change too many parameters at a time, otherwise it will be difficult to understand which one is changing your rendering).

Scale (0.1 - 10): it is the dimension, the diameter that will represent to sun circle. The default value is 1. If you increase the value, shadows will fade away more softly.

Invisible: if checked, sun is not visible in the scene as well as in reflections, even if its illumination effect remains.

Soft shadows quality (0 - 50): this parameter affects the quality of the shadow’s blur. Upper values mean a higher quality, even if rendering time will increase accordingly.

Turbidity: this parameter affects the atmospheric dust quantity. Turbidity affects the sky colour too, especially when sun light has been disabled so that the global illumination is lighter; e.g., if value is more than 10, shadows made by the sun nearly disappear. Low values will let you see a very clear and clean sky with a typical blue colour, and sun is sharped and well-defined like the one you see in the mountains. High values turn the sky colour on yellow/orange, which is typical of metropolitan environments, so rich of dust and pollution. Turbidity can vary in between 2,0 and 20,0.

Ozone: this parameter affects the colour of the light made by the VRaySun. If value is nearly 0, sun light is warmer and colour gets more yellow, while if you move around 1, light is ‘colder’ and colour gets more blue (sky-blue). This parameter does not affect the scene in a very evident way..

Elevation (0 - 90): this value is given in degrees, and tells you about the vertical height of the sun. In this image you can see the sun when at 45°: the project is always placed in the centre of the simulation.
If you move the sun down to 0° you have a less intense illumination, which is typical of dawn and sunset. 90° will give you strong light coming from the top (ceiling) of the room, which is typical of noon.

 You can move the sun in the simulation pane by clicking over it (the yellow circle) with the left mouse button; keep it pressed and move the sun where you need to get the illumination you’re searching for. Such a movement affects both Elevation as well as Azimuth (see next).

Azimuth (-180, 180): this value is specified in degrees, and reveals the sun’s position in the horizon. Again, use left mouse button as seen before, in order to change Elevation and Azimuth.

Environment
Environment section affects the indirect light coming from the sky.

Let’s see it in detail

Type: in this field you can choose whether to use sky colour rather than a custom colour for the environment illumination. A sky colour (as seen before) will create a blue light. A custom one will make the scene being illuminated from all directions by a light defined in the next 2 fields: colour and multiplier. The next images can give a clear idea of the result you’ll get by changing those parameters.

In the next images, you can see how in these circumstances the custom colour will be seen in the background too, unless you decide to use a background image (refer to the Navigation chapter in order to learn how to apply background flat and spherical images). In such a situation, custom colour affects the indirect light of the scene just in case Saturation is different than zero (in the next images it’s been set to 0,7). 

Day time and Night time pre-set buttons automatically setup parameters value in order to obtain a nice rendering in night time (without any natural light), and daylight (with active sun and sky).