Autocad 3D Lighting

The first step in creating models in Autocad 3D is the basic modeling and applying of realistic textures. Then a sense of realism is added to the scene by applying some lighting.

Autocad has three basic types of lighting. Point Lights are like light globes, casting light and shadows outwards in all directions. The Spot Light is the second type and, like its real world counterpart, spreads shadows outwards from the source. The third type of light is the Distant Light like Sunlight in that its shadows are parallel.

It's a good idea when adding lighting to a scene to split the Screen into four viewports via the View tab. Keep three of these orthogonal and in Wireframe mode with Parallel projection. The bottom right you could keep in an isometric view with the Realistic viewing mode. In this manner we can view the objects in the scene from various directions simultaneously. This is especially useful if you have a large screen or a dual screen setup.

Go to the Lights tab to create a Spotlight, and select Create Light, then Spot and Turn off Default Lighting. Establish a position for the light source, for example 500,500,500. Alternativel, click anywhere on the screen and move it into position. Name it Main Light and hit the Enter key twice to see the light "gizmo" appearing. You may now move the light if required. Ensure that the correct viewport is selected and click the Render button to render the scene.

At this point we may see that the shadows are too dark, in which case we can add a softer "fill light", as follows: Light > Point. In the traditional photographic studio this fill light is usually set at right angles to the main light source at about fifty percent intensity. We could name this Fill Light, and render the model again to compare the result.

If the resultant render is washed out or has two sets of shadows, we need to modify the lights. We can do so by clicking the small arrow button in the Lights tab to open the Lights in Model panel. Note that the properties also appear on the top of the right-hand side panels. Various values are shown for the light's Intensity Factor, Position, Colour, Attenuation (otherwise known as falloff) and Shadows. We may also change the light's Intensity here and turn the Shadows off. We could also change the lighting colour in this location. It's best to keep the Main light Intensity Factor at either 1 or 2. We would close the properties to render the scene again.

Note that the last few renders appear at the bottom of the Output File. We can toggle through the list to compare the effects before selecting the preferred image. Then either right-click or go to the File menu to Save the image as a JPEG or TIFF. JPEGs are small in file size, good for first drafts, or to send to a client or a website. Whereas TIFFs are better quality, and as such are good for brochure or magazine presentations. As a footnote, be aware that Distant Lights emulate Sunlight with parallel shadows, but it's best not to use them with Photometric (real-world) lighting. Also note that you don't get a gizmo for a Direction Light or Sunlight.

Tom Gillan has been training Autocad 3D to corporate clients in Sydney for seven years. If you like to know more about Autocad 3D, visit Design Workshop Sydney for more information.

This article was published on 06 Feb 2016 and has been viewed 476 times
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