UE4 – HDRI Environment & Lighting

Software:
Unreal Engine 4.25

Annotation 2020-05-20 162811

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
    Annotation 2020-05-20 153925
  3. Drag a Lights > HDRI Backdrop object to your level:
    Annotation 2020-05-20 154657
  4. In the HDRIBackdrop details, select the wanted Cubemap:
    Annotation 2020-05-20 155212
  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.Annotation 2020-05-20 160338

 

Related:

  1. Sun & Sky link
  2. UE4 Architectural Glazing

Clamp Colors in Photoshop 32 bit float Color Depth

Software:
Photoshop CC 2018

Photoshop CC 32 bit float linear workflow is developing nicely but it still lack some needed basic components, and one of them is a Clamp Color Adjustment, equivalent to a node you will find in any 32 bit float HDR capable compositing software.

Clamping the colors means limiting the britest values to set values, usually 1.0 – white and 0.0 – black, so that no pixels will have higher than white or lower than black (negative) values that can create unwanted results in further operations.

* Brighter than white (super-whites) and negative colors are a feature, and part of linear 32 bit float color processing.

* If there is such an option that I didn’t find please let me know..

In order to clamp the layers colors we convert it to a Smart Object, and convert its color depth to 16Bit internally, so the individual layer gets clamped but the main document remains 32Bit float unclamped (HDR).

To clamp the colors of a layer:

  1. Convert the layer or layers to a Smart Object.
  2. Enter the Smart Object for editing.
  3. From the Image > Mode  menu, choose 16Bits/Channel,
    And in the Conversion dialog that opens choose ‘Don’t Merge’, or choose Merge and then in the HDR Toning dialog choose Exposure And Gamma mode to keep the image unchanged.
    The conversion to 16Bit color depth without Merging or Merging using default Exposure and Gamma mode will clamp the colors.
  4. Save the Smart Object.
  5. Return to the main document, the layers colors are now clamped.