Once you've created a spotlight, you can show the scene in a 3D view from the spotlight's point of view. If you have created more than one spotlight in your scene, you can display a different spotlight view in each 3D view. A spotlight view is useful to see what objects a spotlight is lighting and from what angle.
Every spotlight that has been created in your scene is available from any of the viewport Views menus. The point of view is set according to the direction of the light cone defined for the chosen spotlight.
A flat light distributes light intensity uniformly in all directions and from no specific location. Using flat lighting provides a rough approximation of the general brightness of an area and replaces the complexities of calculating all the inter-object reflections in a scene. All objects in a scene are illuminated equally by the flat light regardless of their location and orientation. The only exception is when a flat light is using a spot light type. In this case, the spot light's interest must be pointing in the direction of the objects it is illuminating. However, by default, the flat light preset uses a point light source.
In general, using a flat light is a more flexible solution than setting global scene ambience because the flat light allows you to define a per-object ambience term using the light's selective property or by adding it to a material's light list (see ). Although you can set a local ambience property on objects and pass partitions, the flat light has the advantage of providing additional light properties such as shadows and distance attenuation that you can tweak to further define the ambient lighting effect.
The light's selective property is set to be Exclusive, thereby not illuminating the objects in its Associated Models list. By default, the Associated Models list is empty, which allows you to pick the objects that you do not want to receive the flat lighting by adding them the list. See .
Area Light is enabled and the geometry type is set to User. In flat light mode, the soft light shader requires that User be set, otherwise, back faces whose normals are pointing away, are not lit properly.
IES stands for the Illuminating Engineering Society. The IES data format is used widely by many lighting manufacturers and is one of the industry standards for photometric data distribution. An IES profile provides the measurement of the distribution of light (its intensity) stored in ASCII format.
IES profiles are created by many of the major lighting manufacturers and can be downloaded for free from their sites. Some of these sites are listed on the Softimage Wiki for your reference.
You can reference an external IES profile from within the shader allowing you to create lights with shape and physically accurate intensities. In scenes with global illumination (using photons), the mia_photometric_light shader takes care of balancing the photon energy and the direct light correctly. When creating lights with IES profiles it is best to use spotlights: point lights and infinite lights do not provide adequate orientation for the IES profile to work from.
On the Photon tab, enable Global Illumination and set the color and Intensity of the photon energy. If your scene uses photons, you must set an energy value for the light source, it will be overriden by the energy value defined in the light shader, but without it mental ray will not emit any photons for the light at all.
In the Light Profile selector, browse for and select an IES profile stored anywhere on your system. The Light Profile selector also displays a 2D representation of the light intensity distribution with some textual information on the profile itself.
Any point or spotlight can be turned into an area light by specifying an area light geometry to determine the shape of the surface from which the light rays emanate. Area lights generate soft shadows because shadow-casting objects may partially obscure the light source, thereby creating a more natural blended shadow (see for details).
Rectangle, Disc, Sphere, and Cylinder primitives can be used with both point and spotlights. The orientation of a given primitive is independent of the light direction and any directional attenuation the light shader may apply, although both should generally be similar.
Geometric area lights (also known as Object lights) can only be created for point lights. Object lights behave exactly as do the pre-defined area light primitives (rectangle, disc, sphere, and cylinder) except that the light's shape is defined based on an object in your scene. All points on its surface emit light uniformly.
Set the Sampling options to control the size of the grid of sample points on the surface of the area light in the U and V directions. Values greater than 5 take longer to render. See and for detailed parameter descriptions.
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