Enhancing a single light source
We are going to create some hot spots on an overhead Softbox without affecting other areas of the HDRI map.
(Thank you to www.pk3d.com for the Demo Scene)
A softbox light has been placed above the car.
Advanced Rotations has been enabled, and Rotation Mode is set to Fixed, so wherever the light is placed using LightPaint, the light is horizontal and aligned with the X axis.
We now want to enhance this light and give it more character by adding some Round Lights with Blend mode Amplify. We will position these lights using LightPaint, to get the effect where we want it.
We can now see the reflection of the Softbox is more dynamic and interesting.
One issue we have is that the new lights are overspilling onto the background HDRI map. We want them to affect only the softbox light, and leave the background alone.
To do this select the 3 lights (Softbox and 2 round lights) and Merge To Composite.
Change the Blend mode of the Composite Light to Over (so that it still appears solid on the canvas).
The round lights are now only amplifying the brightness of the Softbox and the background is not touched.
This diagram shows what we have just created, and how the lighting project is constructed.
We added a few more lights to complete the lighting design, and here you can see the final result, with the softbox provide a lot of character to the reflections with those boosted areas.