Image-based lighting with HDR Backgrounds
Image-based lighting via HDRI skies/backgrounds is a new addition to the the SU Podium lighting workflow starting with SU Podium V2.6 — currently available here in beta.
When image based lighting is activated, it becomes both the background of the render and the primary light source, replacing the SketchUp style and Podium physical skies.
The following video is a comprehensive introduction to image based lighting in SU Podium, explaining the benefits of image based lighting and demonstrating how to use it in SU Podium.
Timestamps: Use the following links to jump to a specific topic
Note - Most of the content in the introduction video is also summarized below:
Activating HDRI lighting in Podium
Choose HDR from the Background drop-down in the environment tab to activate HDRI lighting.
After you have activated image-based lighting, click the HDR tab to select a background image and configure the rotation/exposure of the sky.
The HDR tab
There are three functions that can be performed from the HDRI Sky dialog — image selection, exposure, and camera offset/rotation.
Note - When HDRI is active, the SketchUp sun and shadow angles are superceded. All natural lighting is cast by the HDRI.
Texture dropdown - Included HDRIs
These are the five HDR backgrounds that install with SU Podium. Make your selection from the texure dropdown in the HDR tab.
Additional HDR backgrounds are available in Podium Browser
Podium users are entitled to almost 40 HDRI backgrounds, which will be distributed via Podium Browser due to file-size.
You can also use any HDR background from any external source. Please see here about adding your HDR images to the texture drop-down.
Preview window - Camera linking and rotation/offset
The HDRI preveiw window is set up so that what you see in the preview is the portion of the HDRI you will see in your render. You'll notice that if you move the SketchUp viewport, the HDRI preview moves in unison.
You can fine-tune the portion of the HDRI that will be visible in your render by changing the offset/rotation in the HDRI dialog. So the workflow would be this:
Note - Set your camera view first, save a SketchUp scene, and adjust rotation second, once the camera composition has been determined.
The exposure slider controls the intensity of the light being emitted from the HDRI; real-time feedback in the preview window provides a good approximation of the sky brightness at different exposure values.
The exposure set in the HDRI dialog is not the only factor in determining the brightness of your render, but it is the dominant brightness variable when HDRI lighting is active.
Preset selection and scene configuration (ie - interior vs exterior) still play a role in the overall brightness of the render.
In image-based lighting, the position of the sun is embedded within the HDRI. In other words, the sun you see in the background image is the sun that casts light into your scene. SketchUp date/time settings do not play any role when HDRI lighting turned on.
The only way to change shadow direction when using HDRI is to change the Rotation value in the HDRI dialog.
Please be aware of the following:
- You cannot move the sun relative to the rest of the background image; because of this you may be required to "compromise" between shadow direction and exactly the portion of the HDRI that is visible in the render.
- You cannot change the altitude of the sun—if the HDRI was photographed at 5 PM, the sun will always be in a position consistent with that time of day. The only way to change the sun's altitude in the sky is to choose a different background.
Recommended Presets for HDRI lighting
Because Podium treats HDRI lighting a lot like a large 360° light emitting material, renders may be noisier than usual with many of the standard presets.
We recommend using the Exterior and Interior Fine AA presets when rendering with HDRI.
Note - These are noticeably slower presets, so it is still recommended that you perform test renders with the interior and exterior "default" presets until you are ready to make a final image.
Adding additional HDRI options
1. From Podium Browser
We have a library of approximately 40 HDR backgrounds from HDRI Skies.com available to all users in Podium Browser.
To install an HDR background from Podium Browser, simply click the download icon beneath the thumbnail and it will be available next time you open the Podium HDR interface.
HDR backgrounds are typically 100-350 megabytes apiece and may take several minutes to download. These do not need to be downloaded multiple times — after you install a background from Podium Browser it will be permanently available in Podium unless you decide to remove it manually.
2. From third party sources
You can add any HDRI file as a background option simply by saving any .HDR image into the Podium backgrounds folder. The file path to the HDRI backgrounds folder is as follows:
MacIntosh HD\Library\Application Support\SketchUp 2018\SketchUp\Plugins\PodiumHDR
Any HDR image that you place in these folders will show up in the textures drop-down next time you open the HDR interface:
Third party HDRI Sources
There are vendors all over the world distributing and selling HDRI images for use in 3D rendering — some free, some paid. Here are some recommended sources for HDRI images:
Over 200 free, high resolution (16k), unclipped HDRI images. HDRI Haven is an ongoing community-supported project, funded on Patreon. All releases are completely free with a CC0 license (Public domain / No Rights Reserved). Best free source of HDRI images.