HDR Light Studio takes an alternative approach to working with area lights. Instead of moving lights around in 3D space with X,Y,Z controls or gizmos, as with standard 3D software, HDR Light Studio area lights are controlled with the same LightPaint system used to position the lights on the HDRI map. By clicking on the model in VRED using the the LightPaint modes of Reflection, Illumination or Rim - the area light is automatically moved to a 3D location that provides the required lighting effect.
Unlike lights that are on the HDRI map, 3D Area Lights need to know how far away from the model to be positioned. The Smart Dolly slider in HDR Light Studio is the primary control for distance. It controls both the distance from the LightPaint position to the Area Light, and scales the Area Light at the same time. The further away the light gets, the larger it gets. This ensures the same amount of illumination is reaching the 3D model from the area light however far away it is. In the image above you can see the effect of changing the Smart Dolly values on an area light.
The Dolly Multiplier slider provides additional distance control. It will change the distance without changing the scale of the light. Its value is multiplied with the value from the Smart Dolly distance. Think of this slider as a fine adjustment for distance. Once you have the light in about the right position using Smart Dolly, this slider is good for refining the distance, but without changing the size of the light.
A Creative Approach
By clicking on the model to position the light and then using the smart dolly to change the distance (and scale), this is a really artist friendly approach to lighting. It allows the user to focus on the creative process of lighting the final shot, the user does not need to leave the shot being lit in order to move and adjust lights, its all done in context with real-time feedback. The user doesn't need to worry about the physical size of the lights, but rather on their effect on the shot. The width and height settings for the light are used to control the size of the light as seen by the model, rather than worry about making a light of a specific measurement.
Please Note: In the example below, units in VRED were set to mm.
The default Smart Dolly value for a newly created area light is 1,000. This positions the light 1m (1,000mm) away from the LightPaint position in VRED.
This is also the highest value on the slider (although larger values can be typed, and if you drag off the end of the slider, the value will keep increasing if you have the screen space).
For some scenes 1m is too far away. For other scenes 1m is too close. Therefore we provide an application setting in the Preferences panel to handle different scene scales.
The Smart Dolly Scalar value chosen in Preferences is multiplied with the Smart Dolly slider values for all area lights in HDR Light Studio. This multiplied value then determines the actual distance area lights are placed from the LightPaint position. Making this value smaller will result in area lights being closer (and the range of distances available on the slider smaller), making this value larger will result in area lights being further away (and the range of distances available on the slider larger).
Change the Smart Dolly Scalar value from the default 1 to 0.1 and instantly all HDR Light Studio area lights will be 10 times closer in VRED. (Smart Dolly of 1,000 = 100mm)
Change the Smart Dolly Scalar value from the default 1 to 10 and instantly all HDR Light Studio area lights will be 10 times further away in VRED. (Smart Dolly of 1,000 = 10,000mm or 10m).
A Smart Dolly Scalar value of 10 makes good sense for lighting a car. Lights will be created 10m away initially and the Smart Dolly slider will cover lighting from 0 to 10m. However in this case the area lights may be created outside of the environment geometry and will not be seen in reflections - see here how to fix this.
Please Note: Smart Dolly Scalar is an app preference, not project preference, i.e. the value of Smart Dolly Scalar is shared across all projects opened in HDR Light Studio. This setting can be changed at any time and all area lights in the open project will have their scale updated right away.