Lights and Cameras tab - Houdini online help

Introduction

The Lights and Cameras tab on the shelf is used to create and place lights and cameras in the scene view. Start by placing a key light to illuminate the objects, then fill lights to better define the shapes of the objects in the scene.

After you place a light in the scene view, you can switch it with a different type of light in the operation controls toolbar, as well as modify the light color. This can also be done on the Light tab in the parameter editor.

Types of lights

The following are brief descriptions of the different buttons on the Lights and Cameras tab. Each light tool puts down the same light node, but with different specifications. However, the Ambient Light puts down an Ambient Light node since its unique from the other five.

Point Light

Emits light from a point in all directions and is similar to a light bulb.

Spot Light

Radiates a cone shaped beam of light from a point in a certain direction.

Area Light

Automatically distributes a number of light sources over a specified area. There are five area light shapes to choose from.

Line/Tube	Lights are distributed along the length of a straight line.
Grid	Lights are distributed over the area of a plane. This is the default shape created by the area light.
Disk	Lights are distributed over the area of a disk.
Sphere	Lights are distributed along the outside surface of a sphere. You can put objects inside this shape for an overall soft shadow look that is similar to global illumination irradiance.

Distant Light

Emits parallel rays of light, which are similar to the rays of the sun.

Environment Light

Casts light into the scene as if from a surrounding hemisphere or sphere. The default environment light is a hemisphere; however, you can make it a full sphere by turning on the Use full sphere for environment checkbox on the Area Light Options sub-tab of the Light tab in the parameter editor. You can also change the sampling density in the Area Samples parameter on the Area Light Options sub-tab of the Light tab in the parameter editor.

The position of the light does not matter. You can rotate the light object to orient the light source. With no rotation, hemisphere lights are oriented to cover the region above the XZ plane.

An environment light may use a texture map to provide illumination from an environment map. With no rotation, the environment map is oriented so that the top face aligns with the positive Y axis.

See how to create an environment/reflection map.

Ambient Light

Emits light from all directions to illuminate the scene (source-less light). For specific parameter information, see the Ambient Light node help.

For specific parameter help see the light.

Switcher

Creates a switcher, and switcher node help.

Placing lights and cameras in the viewer

There are three ways you can place lights and cameras in the scene view. Objects can be moved once they are placed by either dragging them in the scene view or changing the values in the parameter editor.

To...	Do this
Place lights and cameras in a specific location in the scene view	Click the desired light or camera from the Lights and Cameras tab. Move the cursor into the scene view. You can hold Alt to detach the shape from the construction plane. Click to place the light or camera anywhere in the scene view.
Place lights and cameras at the origin	Click the desired light or camera from the Lights and Cameras tab. Move your cursor into the scene view and press Enter to place the shape at the origin.
Place a light or camera by looking through it	Ctrl click the desired light or camera from the Lights and Cameras tab. Use the handles or edit the values in the parameter editor to move the light or camera to the desired location in the scene view. When looking through the camera there are handles on the sides of the scene view which allows you to orient and crop.

To...

Do this

Place lights and cameras in a specific location in the scene view

Click the desired light or camera from the Lights and Cameras tab.
Move the cursor into the scene view.

You can hold Alt to detach the shape from the construction plane.
Click to place the light or camera anywhere in the scene view.

Place lights and cameras at the origin

Click the desired light or camera from the Lights and Cameras tab.
Move your cursor into the scene view and press Enter to place the shape at the origin.

Place a light or camera by looking through it

Ctrl click the desired light or camera from the Lights and Cameras tab.
Use the handles or edit the values in the parameter editor to move the light or camera to the desired location in the scene view.

When looking through the camera there are handles on the sides of the scene view which allows you to orient and crop.

Handles

Clicking on lights and cameras in the scene view gives you more camera and light manipulator handle options. The two that are unique to lighting are the cone handle and the frustum handle. The two that are unique to cameras are the focus handle and the frustum handle.

Cone handle	Allows you to control the delta and cone angle.
Frustum handle	Allows you to set the near and far clipping planes and the focal length.
Focus handle	Allows you to control the depth map focus.

Use the view keys to move a light or camera

Look through a light or camera as described above. You can also choose a light or camera to look through once it is created by choosing it in the camera menu.
Lock the light or camera to the view by clicking the Lock camera/light to the view button, which is located on the toolbar on the right side of the view. You can also lock the light or camera to view by by turning on Tie Camera (or Light) to View in the camera menu.
Use the tumble, track, and dolly keys to move the light or camera.
Unlock the light or camera to place it.

Make a light or camera look at an object

Create an object.
Create a light or camera.
Click Look At on the Modify shelf.
Select the object to look at and press Enter .

You can also make a light or camera look at an object by setting it on the Lookat Options tab on the Transform tab of the parameter editor.