IRender Tutorials - Basic Concepts

This Ray Trace Concepts Tutorial discusses some of the differences between Photorealistic Ray Trace Rendering and OpenGL Rendering. (OpenGL is is used by SketchUp ).


Overview and expectations

This is a sample image saved from SketchUp demonstrating shading, transparency, materials, etc.

Ray Trace is a rendering technique in which each object in the model is traced along a ray until it reaches the eye.

If you simply take a SketchUp model and run it through a Ray Trace engine to get better renderings, you will not get a rendering better than what SketchUp does already. You need to enable some of the Ray Trace, photorealistic features in order to get a better looking rendering.

This Tutorial will show you how to implement some of these features into IRender.


SketchUp uses an OpenGL rendering engine. Through the use of textures, edge highlighting, smoothing, sun shadows, etc., SketchUp can achieve good renderings of your 3D model.

OpenGL's development is driven by the computer gaming industry to create realistic scenes for computer games and continues to improve at a rapid pace because of the interest in, and money being spent on computer gaming. The important things to this industry are speed of rendering and realistic scenes.

This is the same model run through the IRender renderer demonstrating lights, multiple shadows, reflection, Antialiasing, and soft shadows.


IRender utilizes interior light sources, multiple shadows, reflection, and other features to create higher quality renderings.

See the Wiki article on Photorealism for more information.

Example of Specular Reflection to make table top and brick wall appear shiny.

Materials: Mirrors and Reflection

IRender uses the materials defined in SketchUp, and also offers additional material and texture options.

A mirror , a reflective table top or floor, and Specular Reflection on shiny objects will make a better rendered image.

The Ray Trace image at the top of this article demonstrates Ray Trace mirrors on two walls.

Mirrors and Specular Reflection are set in IRender by adding a reflection property to a mirror definition. This can be done by right clicking on a face containing the material and clicking IRender: Edit Material.


Shadows from the sun. Rendered with SketchUp.
Multiple shadows from street lights.

Shadows and Lights

Shadows add to the Photorealism of a rendered model.

Shadows from the sun, and shadows from lights can greatly improve the quality of a rendering.

Shadows in SketchUp

SketchUp displays shadows from the sun, using the Shadow Settings dialog box to specify the day of the year, and the time of day. to create the shadows.

IRender reads these shadow settings and automatically uses them as part of the Ray Trace process.

Multiple Shadows

IRender also casts shadows from other light sources to create a more realistic effect for interiors or night scenes.

Living Room model downloaded from Google 3D Warehouse. 2 SketchUp light fixtures and one IRender spot light (in yellow) added with SketchUp.
Model rendered with IRender. Note the display of the spot light bulb is optional

IRender automatically casts light and shadows from the lighting components in the SketchUp Architecture and Landscape libraries. Select one of these lights and place it in your drawing.

Note: In the image on the right, the Spotlight is visible. This is an option in IRender, you can suppress the display of the light bulb itself.

More on Lights

Setting Up the Environment

In addition to setting up items in SketchUp there are settings you can make during the Ray Trace process.

Lighting Parameters

There is no "right" answer to how bright a room should look with a given set of lights. It often depends on other factors, like the brightness where the observer is standing. So Ray Trace programs often have settings which effect the overall brightness of the scene.

If a scene is too bright, use the Brightness Slider on the Render Window.


IRender provides a dialog to balance Ambient Light and light from lamps and light fixtures. If the scene is the right brightness, but the shadows are not visible enough, try lowering the Ambient light and raising the Lamp light factor with he slider bar on the Light Setup tab

Light Tab.jpg


Simple SketchUp model rendered with no Antialiasing. Each of these examples shows the image at normal size on the left and blown up 2 to 1 on the right to demonstrate how Antialiasing is performed.
Same model exported at 4X the desired resolution and then reduced in an image editing program.

Antialiasing makes edge lines look smoother by blending in the colors at the edges.

You can perform antialiasing from SketchUp by rendering your model to a higher resolution using " Export 2d Graphic ", and reducing the image in an image editing program such as Photoshop .

Many Ray Trace programs include settings for automatically performing antialiasing during the rendering process.


This Tutorial discussed Antialiasing, Lights, Shadows and Reflection. These few features will make much more stunning renderings of your Ray Trace models.

You will find that you need to experiment with amount of reflection, intensity of lights, position of lights, etc. to get the best image.

There are many other features such as Glow , Indirect Light , Solid Materials , and IRender nXt Plants which will make even better renderings.

Video Tutorials

We have created a number of Video Tutorials which will help you get started.
Rendering with SketchUp
How-to-render.jpg How to choose a renderer
Sample-renderings-thumbnail.jpg Sample Renderings
First Exterior Rendering.jpg First Exterior Rendering

Video2.jpg Simple Rendering of an Object

Getting Started
Getting started video.jpg Getting Started with IRender nXt
Getting Started with nXtRender.jpg Getting Started with nXtRender

Interior lighting button.jpg Interior Lighting Basics
Reflections video.jpg Highlights and Reflections
IRender nXt Videos
IRender nXt Video.jpg IRender nXt Features
Version3-video.jpg Advanced IRender nXt Features
Pback2.jpg Position your Background Image
Position HDRi.jpg Position HDRi Sky

Glass transparency.JPG Fine Tuning Transparency
Button for edge lines vid.jpg Rendering with Edge Lines
Lighting-channels-video.jpg Lighting Channels

Material-channels-video.jpg Material Channels

Realistic Water Effects.jpg Realistic Water Effects
Create 3D PDF.jpg IRender nXt 3D PDF

Other SketchUp products

NprTools Video
  • Add non-photorealistic effects to your SketchUp Model.
  • Soft Shadows
  • Sketchy Shadows
RpTreeMaker Video
  • Add custom, fractal trees to your SketchUp Model.
  • Create a simple tree and see how to change the parameters.
Treemaker button.jpg

AccuRender nXt for Revit

AccuRender nXt Simple Rendering
  • Load and use AccuRender nXt for Revit
  • Render a model with default settings
Revit button.jpg

See Also