UE4 – HDRI Environment & Lighting

Software:
Unreal Engine 4.25

Creating HDRI environment backgruond and lighting* in UE4:
Note:
Lighting using a panoramic HDRI background is also referred to as IBL – Image Based Lighting.

* The example HDRIs in this post are from www.hdrihaven.com

1. Import HDRI environment file.
   Note:
   The file must be saved as a *.hdr file and not *.exr because AFAIK that’s the only way UE4 will recognize it as an HDRI environment and encode it as a Texture Cube (cube map)
2. Enable the HDRIBackdrop plugin:
   Go to Edit > Plugins
   Type “HDRI” in the search field to locate HDRIBackdrop and enable it.
   * You’l have to restart the UE Editor before using the plugin
   
3. Drag a Lights > HDRI Backdrop object to your level:
   
4. In the HDRIBackdrop details, select the wanted Cubemap:
   
5. > Set the HDRIBackdrop‘s Intensity (self explanatory..).
   > Rotate the HDRIBackdrop around its Z axis to set the environment’s direction.
   > Set the HDRIBackdrop‘s Size.
   * Make it larger than your whole scene,
   And if Use Camera Projection is unchecked make it also large enough so that noticeable objects in the HDRI image will be distant enough as to not move incorrectly when you strife.
   * When Use Camera Projection is activated the Size property has no effect.
   > If Use Camera Projection is unchecked, set the Projection Center Z value to define the background image height below which it is projected as a flat ground.
   > Lighting Distance Factor defines ground projection area that will appear to receive shadows from your scene objects.
   * Set this attribute to 0 in-order to turn off the ground projection shadow.
   > Use Camera Projection:
   Activate this option to get a traditional infinitely far background with no flat ground surface projection.

Related:

1. Sun & Sky link
2. UE4 Architectural Glazing
3. 3ds max & V-Ray to UE4 Datasmith workflow
4. Preparing an FPS project for archviz
5. UE4 – Archviz Light calculaion tips