I've been using Isotropix Clarisse in production for a little while now. Recently the VFX Facility where I work announced the usage of Clarisse as primary Look-Dev and Lighting tool, so I decided to start talking about this powerful raytracer on my blog.
Today I'm writing about how to set-up Image Based Lighting.
- We can start by creating a new context called ibl. We will put all the elements needed for ibl inside this context.
- Now we need to create a sphere to use as "world" for the scene.
- This sphere will be the support for the equirectangular HDRI texture.
- I just increased the radius a lot. Keep in mind that this sphere will be covering all your assets inside of it.
- In the image view tab we can see the render in real time.
- Right now the sphere is lit by the default directional light.
- Delete that light.
- Create a new matte material. This material won't be affected by lighting.
- Assign it to the sphere.
- Once assigned the sphere will look black.
- Create an image to load the HDRI texture.
- Connect the texture to the color input of the matte shader.
- Select the desired HDRI map in the texture path.
- Change the projection type to "parametric".
- HDRI textures are usually 32bit linear images. So you need to indicate this in the texture properties.
- I created two spheres to check the lighting. Just press "f" to fit them in the viewport.
- I also created two standard materials, one for each sphere. I'm creating lighting checkers here.
- And a plane, just to check the shadows.
- If I go back to the image view, I can see that the HDRI is already affecting the spheres.
- Right now, only the secondary rays are being affected, like the reflection.
- In order to create proper lighting, we need to use a light called "gi_monte_carlo".
- Right now the noise in the scene is insane. This is because all the crazy detail in the HDRI map.
- First thing to reduce noise would be to change the interpolation of the texture to Mipmapping.
- To have a noise free image we will have to increase the sampling quality of the "gi_monte_carlo" light.
- Noise reduction can be also managed with the anti aliasing sampling of the raytracer.
- The most common approach is to combine raytracer sampling, lighting sampling and shading sampling.
- Around 8 raytracing samples and something around 12 lighting samples are common settings in production.
- There is another method to do IBL in Clarisse without the cost of GI.
- Delete the "gi_monte_carlo" light.
- Create an "ambient_occlusion" light.
- Connect the HDRI texture to the color input.
- In the render only the secondary rays are affected.
- Select the environment sphere and deactivate the "cast shadows" option.
- Now everything works fine.
- To clean the noise increase the sampling of the "ambient_occlusion" light.
- This is a cheaper IBL method.