World Mixer
World Mixer allows you to quickly add HDR images with simple controls to your World material.
If no Photographer World material is present, you will see a Add World HDRI button. This will create the material network to use a 360 HDRI image that is be present in your World HDRI library folder, which can be set in the add-on Preferences (World HDRI Library path)
Only HDR and EXR files will be recognized in that library.
Thumbnails will be automatically generated for HDR and EXR files that are smaller than 100MB.
PNG files with the same name as the HDR/EXR files can be used as thumbnails for large files or to speed up the menu opening.
You can generate the thumbnails directly from the World Mixer panel by clicking the Images icon at the top right of the HDRI image preview.
Input Color Space: Set the Color Space of your HDRI image, this is defined by how the HDRI was created. If you do not know, it is probably Linear Rec.709.
Rotation: Rotates the HDRI environment.
Horizon Level: Moves the HDRI horizon up or down.
Blur: blurs the HDRI environment (requires a high enough number of samples).
Temperature: Multiplies the HDRI using Color temperature in Kelvin (uses Blackbody node).
Tint: Multiplies the HDRI with green or magenta.
Hue / Saturation / Value: Adjusts color of your environment.
Diffuse: HDRI environment visibility for diffuse reflection rays.
Glossy: HDRI environment visibility for glossy reflection rays.
Camera: HDRI environment visibility for camera rays.
Lightgroup: Assign a lightgroup to your World to be able to control it in compositing.
BG Color (Background Color): Replace the Sky with a Solid Color, while keeping the Sky lighting contribution and reflections.
Note that changing the Camera or Scene Exposure will affect the perceived brightness of Background Solid Color that you selected. You can use the Exposure Compensation operator to fix it.
When using an HDRI image, you will get the possible to add an HDRI Ground Mesh.
There are 3 types of meshes: Plane, Cube and Dome.
Planes are limited in perspective as the height of the camera needs to be close to the one that was used during the HDRI capture. Scale the plane object to adjust the Lighting distance (how far it will receive lights and shadows.
Cube allows you to project to a mesh that can be modeled and adjusted to the captured environment. Just make sure to not scale the Object itself, but move the vertices inside the mesh.
You can add more faces and do not need to keep it as a single cube!
Projection Height and Lighting distance can be adjusted.Dome is better for exterior environments with far horizon lines.
Projection Height and Lighting distance can be adjusted.
Add HDRI Ground Meshes using the header icons
These are using a special technique suggested by vklidu, different from the regular shadow catcher, which supports lighting and reflections (to some extent). You can read more about this technique here and in this thread.
This technique has one caveat: after adding the plane, you may notice the ground brightness and color doesn't exactly match the HDRI sky.
This is because the ground receives diffuse lighting from the Sky itself, and we need to manually compensate for it in order to cancel this contribution.
You can manually compensate using the Tint and Intensity values, but it's much easier to use the Picker and pick the color from the ground.
Tip: Adjusting World properties with the Cycles Render view active can be extremely slow due to the Auto Sampling Method (Updating Lights will be written at the top left of the viewport).
Either use the Material Preview with Scene World enabled (recommended), or change the World Sampling Method from Auto to Manual.
Don't forget to set the Sampling Method back to Auto afterwards, for best render results.
If your HDRI includes the sun in its full dynamic range, make sure to pick the color of the plane in the sunlight, not in the shadows of your objects.
You can now easily integrate your objects into the HDRI, that will receive shadows, lights and caustics.
Reflections can also be added if needed, although their look and realism will really depend on the type of scene.
Note that the Reflection value is NOT the specular value of the Principled BSDF and represents the actual reflectance of the material.
For dielectric materials ( = glass or plastics, not metals), reflectance should be set to 0.04.
