Visualizing a bathroom with SketchUp, Podium Browser, and ProWalker GPU / SU Podium

Materials and their settings - from Podium Browser unless noted

The majority of the materials in the scene are from Podium Brower, with one or two exceptions. All the major surfaces in the model are documented below:

Materials that were already applied to Podium Browser components are not pictured above, but some of them are covered in the tutorial video. A few of these include the white acrylic material applied to the bath and splash guard (94% diffuse, 6% reflection), the vanity countertop (85% diffuse, 15% reflection), and various light emitting materials (explained in the next section).

Background HDRI settings and artificial lighting

The main source of light in the scene is the window above the bathtub. ProWalker GPU gives us two options for natural lighting — a physical sky simulation that uses SketchUp's date/time system to determine the angle and intensity of the sunlight/shadows in your image. The other option is to use image-based lighting driven by an HDR background image.

For this image I used the "Afternoon 01" background setting, with the offset set to 77 degrees. ProWalker GPU provides five HDR background options, but additional backgrounds can be downloaded and installed from the ProWalker website, or from third party sources like HDRI haven.

The offset slider controls the rotation of the background, and determines the angle and distribution of light and shadow in the render. Our chosen offset of 77 degrees places the sun to the left and slightly behind the window, causing most of the sunlight to fall on the shower and bath alcove.

The reference has several artificial light sources — for the suspended chandeliers and recessed lights, I used components from Podium Browser. The wall mounted light fixture over the vanities was modeled by eye from the reference (included in starter model download). I deleted the omni lights from each of the two Podium Browser fixtures, and used light emitting materials instead.

A large light emitting material panel was placed in the room behind the camera to cast additional light into the scene — the main purpose was to hit the vanities with a small amount of reddish/pinkish light. I wanted the effect to be very subtle, and kept the LEM Power as low as possible.

ProWalker GPU does not have a "soft omni" option — Unlike SU Podium, ProWalker GPU does not have a soft omni option, so there isn't a way to soften the shadows cast by omni lights. Because there are no "hard shadows" in the reference image, I decided to delete the omni lights from the chosen light fixtures, and replace them with Light emitting materials. This is depicted in the video at 00:53:40.

Lighting / Tone-map and Termination Criteria

Lighting and tonemapping settings are explained in detail in the tutorial video at 1:21:58.

LEM Brightness — One difficulty when using ProWalker GPU is that light emitting materials are quite overpowered in ProWalker versus a comparable LEM in SU Podium. In other words, if you have a light emitting material with a light power of 7, that LEM will be significantly brighter in ProWalker than it is in SU Podium.

The solution for this is to use the global LEM slider, and drop the value far below the default value. Setting the LEM slider to ~0.1/0.2 tends to work well for LEM materials with a light power between 1-10. For this image, I set the LEM slider to 0.2.

Physical slider - The physical slider controls the brightness of "natural" light sources in ProWalker — this includes the physical sun/sky simulation, or the HDRI background image, depending which option is selected. I wanted the window to be the primary source of light in my render, so I moved the Physical slider to 5.2 to substantially increase the amount of light being cast into the room by the HDRI background.

Termination criteria

It's hard to make a broad suggestion with regard to termination criteria (samples), because every model is different, every user has different hardware and different tolerance levels for noise in an image.

Interior renders with artificial light typically require a lot of samples when using PR mode — for this type of image, more than one-thousand samples are usually needed both with and without the denoiser turned on. I personally don't mind a little bit of noise in a render, and prefer subtle noise over the "softness", or loss of clarity that the denoiser can introduce.

For my render I turned the denoiser off, set the termination criteria to 4000 samples, and let the render run overnight. In the close-up crop pictured right, it's clear there is still some noise in the image, however I do not think it detracts from the render. When zoomed further out, the noise is less noticeable, and I find the subtle texture appealing.

Exporting a still image from ProWalker

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Don't forget that the image seen in the ProWalker viewport is simply a preview render. After you have chosen your background, configured your lighting, and determined your termination criteria, you must use the "capture an image" button to render and export a still image. This is covered at 1:28:32 in the tutorial video, or simply watch the short timelapse below: