Shaderlight forums

I’m not at a computer with the most recent version of Shaderlight right now.

However, I believe there are two places for images in the setting dialogue.

1) Under “Lighting” once you select “Custom” there is a field to select your HDRi that will provide the light for the scene.
2) At the bottom of the settings dialogue, there is a section called “Background”
—to use the HDRi as your background, you select “Lighting Environment”.
—to use the background image, you select “Custom” and use the field below to select the alternate background image to be shown.

Cheers,

Andrew

Andrew is correct. To expand on this somewhat…

Typically, you would use the HDR image for a ‘Custom’ Lighting Type and a JPEG as a ‘Custom’ Background.

The Lighting section controls what light is received by your SketchUp geometry and the Background section controls what is seen in pixels that don’t hit any SketchUp geometry. The ‘Lighting Environment’ option in the Background Preset setting allows you to make the Lighting HDR do double-duty, so that the HDR image used to generate the lighting is also used as the background image.

This has the benefit that the view of the background will always exactly match the lighting, so you can’t get weird, inconsistent shadow directions, colour casts or lighting imbalances.

The disadvantage is that the HDR map is almost always going to be of inferior quality. First, because it covers the entire sphere, any given viewport is only looking at a small section of it, so that, unless it is absolutely huge, it will be expanded to fill the viewport, making it look blurry. (e.g. using SketchUp’s default 35˚ field of view and rendering at 1920 x 1080, the HDR would need to be over 10,000 x 5,000 pixels. Some of the sources that Andrew mentioned do have HDRs at that kind of resolution, so you may get excellent results using those as a background image, if you have enough memory to load it!) Secondly, HDRs are generally processed (or rather, unprocessed) to have physically accurate lighting rather than an appealing appearance, so they can look rather bland. A separately processed JPEG that has been tweaked to look good and saved at a suitable resolution for the final render will look better for less memory usage. Of course, then you are limited to the viewpoints that have been provided in the JPEGs.

At least, that is how I would expect HDR packs containing both an HDR image and a set of JPEGs are intended to be used – I could be mistaken. If you would like me to comment on a specific freely-available HDR pack, please do mention it here.

Shaderlight will allow you to use any image for both the Custom Lighting Type and the Custom Background, but in general, only HDR images in ‘lat-long’ format are really suitable for the Lighting Type. A lat-long format image is twice as wide as it is tall and represents all directions in a sphere (all 360 degrees around the longitude and 90 degrees each up and down in latitude). Other aspect ratios will be stretched by Shaderlight in order to fill the whole sphere, so will appear distorted and may have a discontinuity where the edges are joined together – if you try loading one of the JPEG backplate images into the Custom Lighting Type slot, use the ‘Lighting Environment’ Background Type and render an empty scene with auto-update enabled, you will be able to spin the camera around until you see a seam in the environment because the backplate doesn’t represent the whole 360 field of view.

Conversely, loading a lat-long HDR image into the Custom Background slot will produce weird results because it will crop the image to fit the render resolution and the cropped image probably won’t match the field of view of your render.

The attachments show reduced-size versions of Shaderlight’s built-in ‘Golf Course Evening’ HDR map and one of the backplates (available to download), which may help visualise what I’m getting at. Notice that the backplate shows quite a small subset of the HDR map (in this case spanning the join between the edges of the HDR map).

The ‘correct’ way to use this type of HDR pack is to first crop and resize the backplate image to match your output resolution, then line up your lighting environment to match the backplate image and then finally to render with the backplate in place:

1) Use an external image editor to crop and resize the backplate, if it doesn’t already match your desired output resolution.

2) Load the HDR image into the Lighting Type slot (in this case, Preset / Golf Course Evening, but use Custom and select the HDR file for a third-party HDR pack).

3) Set the Background Type to Lighting Environment.

4) Hide most / all of the SketchUp objects in your scene so that you can clearly see the background in the render.

5) Render in low resolution / quality with auto-update enabled and rotate the SketchUp viewport until the background matches the backplate image as closely as possible. (It minimally needs to point at the centre of the backplate image. You can also try to match the field of view of the backplate by adjusting the FOV of the SketchUp viewport so that the edges of the render also match the edges of the backplate. This won’t affect the lighting, but might make the perspective of your SketchUp objects match the backplate better.) Unfortunately trail-and-error is the only practical method here. This step will ensure that your lighting matches up with what’s visible in the background.

6) Set the Background Type to Custom and load in your resized backplate image. (The Shaderlight render should now look basically the same, but sharper due to the use of the high-res backplate.)

7) Re-show your hidden SketchUp objects and render at final resolution and quality.

This is quite long-winded and you can often get away with skipping some of these steps – especially for interior renders where not much of the background is visible and artificial lighting is predominant.

Finally, as you have discovered, there is no way to independently control the brightness of the illumination provided by the HDR environment. The reasons for this design choice are somewhat lost to the mists of time, but I suspect the feeling was that it was an unnecessary control since you can achieve the same thing either by adjusting the overall exposure (and correspondingly adjusting the intensity of the artificial lights) or by editing the HDR file itself in an external editor. Given that we now strongly recommend using physically accurate artificial lighting intensities, I feel that decision needs to be revisited, so we may well add that control in a future release.

Regards,
Shaderlight support

Excellent descriptions.  I understand much better now. I was stupid to not notice that Lighting and Background both had ability to load files.  The step-by-stem process for HDR and the background is very helpful.
Thank you both so much for your help!!!

Just wanted to post a couple of my final images and thank you both for your help in this process.

Great work! Thanks very much for sharing.

Regards,
Shaderlight support

kfoojones - Mar 17, 2020 04:12pm

Great work! Thanks very much for sharing.

Regards,
Shaderlight support

I’m starting to get a workflow.  Obviously making components of identical fixtures with the same IES or light source is key.  I have the light sources on a different layer too so if I’m showing someone an image in raw sketchup, i don’t have the little light symbols everywhere. As there isn’t a table or database of all fixtures where parameters can be controlled globally, I make my own “schedule” off to the side in sketchup.  Just line up the lighting components and add some text nearby to identify them.  (Ex”  Lite-Fixt_Cafeteria_Ceiling Pendant Feature_02)

Then I can edit several fixtures in one convenient location.

I am also grouping fixtures on different layers.  There’s no sense lighting a portion of the building that is not even seen in a new render. I have found that 84 fixtures located elsewhere REALLY slow down the render time for my scene!  So I just flip the layer off and Re-Save the sketchup tab for that scene.  One thought is that it could be conveniernt to make a lighting fixture with several “power” settings.  For example, the typical 2x2 lay-in fixture could have three spotlights at varying spreads and/or lumen levels…with each of the light points on a separate layer (Ex:  “Fixt 02_Litepoint_Low lumens-narrow Spread”...and…“Fixt 02_Litepoint_High lumens-wide spread”)

Then just flip those layers on and off for the desired effect in various scene/render tabs.

Those are some great tricks to help manage complex lighting setups.

Another one we have suggested in the past is to use SketchUp’s Outliner window and search field to find components named “Shaderlight”, which should filter out all of your light objects. But having the ‘schedule’ of lights off to the side sounds like it would make things really quick and easy to find.

Many thanks,
Shaderlight support