Lighting is an essential part of rendering. By default, templates contain some standard basic lighting configurations (like environment or sun+sky lighting), but you can add some more lights to enhance your rendering.
The general method to add a light to your rendering project is the following:
- Create the light object
- Place the light in your scene (and orient it if applicable)
- Tweak the light power and color
- Add a view of the light in your project. This is a mandatory step to
have the light eventually rendered! Use
button, like for
objects...
The lights we support are very common ones in the rendering world. Therefore we will only give a brief description for each of them: you may find more detailed explanations in computer graphics literature or web contents, or in your renderer documentation.
The point light is an omni-directional infinitely small source of light, meaning that it emits light equally in all directions, similar to a lightbulb or a candle flame.
To create a point light, press the corresponding button in toolbar: 
Do not forget to add a view of your light to your rendering project.
In FreeCAD viewport, point light will be represented by a dashed "star":
The size of the star is controlled by the Radius parameter, which should be
useful to adapt the light representation to your scene dimensions. Please note
this parameter is just dedicated to viewport seeing, and has no effect on
rendering.
The representation in FreeCAD viewport casts light onto objects, but this is just for convenience and does not prejudge the final rendering.
Point light is the most basic light, its parameters are simply Placement, Power,
Color.
Pov-ray specifics: due to Pov-ray particular implementation, power parameter is
internally clamped to 100 when exporting to this renderer.
The area light is a rectangle emitting light on all its surface in the direction of its normals.
To create an area light, press the corresponding button in toolbar: 
Do not forget to add a view of your light to your rendering project.
In FreeCAD viewport, an area light will be represented by a luminous rectangle:
The representation in FreeCAD viewport casts light onto objects, but this is just for convenience and does not prejudge the final rendering.
The size of the rectangle is determined by Size U and Size V
parameters. Those parameters influence the rendering, as they are exported to
the renderer as the dimensions of the area light to render.
The Transparent parameter is a boolean to control the visual appearance of
the area. If False (default value), the area will appear as a luminous but
opaque rectangle; if True, the area will be invisible and will affect the
scene only by the light it casts.
Please note that the Power parameter refers to the power of the whole area,
and not to the power per unit area.
Renderers specifics :
- For renderers using a power per unit area (like Appleseed), a conversion is made when exporting.
- Pov-ray: due to Pov-ray particular implementation,
powerparameter is internally clamped to 100 when exporting to this renderer.
Orienting an area light in a scene may be quite painful. To alleviate such a
task, you will find a Point at... feature in the context menu of the light
(right-click on the light in the tree view). Trigger Point at..., select the
object your area should point at, and the workbench will orient automatically
the area to the object.
Sun & sky light simulates a solar and atmospheric lighting, as existing at Earth's surface. It will consist into 2 parts: the direct sunlight (a direct light altered by atmospheric scattering) and the skylight (an environment light resulting from indirect sunlight diffusion). Sun & sky is particularly useful in architectural rendering.
To create a sunsky light, press the corresponding button in toolbar: 
Do not forget to add a view of your light to your rendering project.
There is no representation of sun & sky light in FreeCAD viewport.
The Sun direction parameter controls the position of the sun in the simulated
sky. It is a vector representing the direction of the sun as seen from an
observer on Earth. A few things to keep in mind with this parameter:
Sun directionshould not be a null vector.- Negative z component (sun under horizon) may create issues with some renderers.
The turbidity parameter controls atmospheric turbidity. Values < 2 may create
issues with your renderer. Refer to your renderer documentation, or general
documentation on sky simulation, for more information.
The ground albedo parameter controls the ground albedo, ie the reflection
coefficient of the ground. It must be comprised between 0.0 and 1.0. Refer to
your renderer documentation, or general documentation on sky simulation, for
more information.
Sun & sky light is a complex feature to implement in a renderer. Nowadays, efficient renderers generally use Hošek-Wilkie model to render such a lighting: this is the case for Appleseed and LuxCore, for instance. In other renderers, the support may be partial (Cycles: only sky is correctly implemented) or inexistent (Povray); in which case, an approximate method will still be employed in the workbench to compensate the missing feature, but the result might be less realistic.
Image-based lighting is a lighting technique based on projecting an omnidirectional picture of an environment onto a dome surrounding the scene.
To create a image-based light, press the corresponding button in toolbar: 
Do not forget to add a view of your light to your rendering project.
There is no representation of image-based light in FreeCAD viewport.
Image File: the file containing the image to use (should be a HDR). Please
note the image file is embedded into the FreeCAD file.
- The final effect of a light in a rendering directly depends on the renderer's capabilities. The effect of a light may vary a lot from one renderer to another. The only way to get it right is to try and experiment...
- Just like other objects, the light will be exported to the renderer only if
its
Visibilityis set toTrue.