Blending with Backdrops: LightUp for SketchUp

By Adam Billyard

This tutorial will get you started on how to set up a model using LightUp for SketchUp, a SketchUp plugin that adds realistic, realtime lighting to your SketchUp models. This tutorial will cover:

• Using Image-based Lighting (IBL)
• Blend shadows from your model with a backdrop
• Position the backdrop relative to your model
• Adjust the field of view.

Ok, let us start with a SketchUp model of a Jeep (by Brian Carver, 3D Warehouse).

SketchUp Model

We are going to light this model at 4cm intervals. Choosing Resolution is about trading lighting time for fidelity and typically you’d start with a lower Resolution while rigging, but this model will only take a minute or so in total, so we’ll start with a higher Resolution.

We are using “Ambient Occlusion” with “IBL blend” selected. This means LightUp will use the backdrop as the source of light and ensure that the model blends naturally with the backdrop. Further down, you can also see “Show Skybox” is checked. I have chosen a HDR backdrop of a field.

Preferences

If you press the Tourtool button to start lighting, you should shortly get something like shown in the image below.

Image so Far

Let us assign some material properties by clicking on materials and editing the realtime material properties. We will edit the windscreen, wheel rims and bodywork materials.

Windscreen Material

Windscreen Material

Wheel Rim Material

Wheel Rim Material

Bodywork Material

Bodywork Material

While material assignment improves the look, the Jeep looks like it is “floating in space” and makes no effect on the background. To solve this we are going to add a groundplane on which the vehicle can sit. Exit LightUp Tourtool by choosing a SketchUp tool or pressing Escape.

In order that the ground plane shows only the shadows cast on it, we will mark it as a “Shadow Catcher”. LightUp treats materials marked as “Shadow Catcher” differently during Tourtool and blends only the shadows and not the direct lighting falling on the surface.

Mark Ground Plane as Shadow Catcher

Now when we start Tourtool again, we have a ground plane that captures the shadows of the Jeep and blends them with the backdrop. The Jeep no longer looks like it is floating in mid-air, but parked firmly on the ground.

Ground Plane Captures Shadows

Adjusting Backdrop and Field of View

The great thing about a realtime renderer is you can adjust things instantly without having to wait for another render to finish. The backdrop is fine, but I don’t want to see that brick building in the background. I want to Pan the backdrop around to a better view. I can do this easily in Lightup, by holding down Ctrl on the backdrop and dragging the mouse left and right.

Adjusting Backdrop

Better.. still I need to pan around a little more….that is perfect.

Adjusting Backdrop Further

Lastly, we are going to tighten the Field of View. Again we can do this all inside Tourtool by holding down Ctrl on the backdrop and dragging the mouse up and down. You’ll see the current Field of View in degrees showing in the lower right corner of the window.

Adjust Field of View

Thats it!…our final image is nicely blending with the backdrop, using image-based lighting.

Final Image

Thanks for reading this LightUp for SketchUp tutorial.

Adam Billyard