Once built, we add lighting and materials to an Autocad 3D model in order to simulate real world appearance. The model is then rendered either as a still image or as an animated movie sequence.
It's best to add a ground plane to the model, whether for architecture, interior design or engineering. This is done by typing planesurf into the Command line and creating a large rectangle as a base for the model, which will then show the shadows when the lighting is applied.
The next step is to add the lighting. There are various types: generic spotlights, point lights and distant lights. Or Photometric lighting can be added which simulates the attributes of real-world lighting.
If the scene turns black it's due to the default Photometric lighting units. This can be changed by typing UN into the Command line, or clicking on the Lights drop-down arrow. We would change American lighting units or International lighting units, both for Photometric lighting, to Generic lighting units for standard lighting. Please note that some materials, for example Realistic Metals, only work in conjunction with Photometric lighting.
Now we render a still image of the scene by going to the Render panel and click the Render button. A scene usually takes only a few seconds to render, depending on the complexity of the scene and the render quality. Lighting may be adjusted at this stage, as well as the camera view. Then we re-render the scene. Also note that renders create only temporary files which are not be saved when we close the model. To save a render go to the File menu and choose Save, followed by Type: JPEG or TIFF, with the Best Quality setting.
To render a short animation, we would first create a camera path using the Ellipse or Spline tool, which we then elevate it above the model so that the camera is looking down on the scene. If the Animations panel is not visible on the Ribbon, we right-click on the Ribbon to select Panels, then select Show Panels and Animations. Then we can select the large Animation Motion Path button.
Note also the Camera section. Here we select the Path radio button, and the Select Path button. Then click on the Spline you previously created and name it Camera Path. Select the Point radio button on the Target section, and click the Pick Point button. Next click on the centre of scene and hit Enter. This will specify the target point around which the camera will point to as it rotates. We can also click Preview to view it.
Next we adjust the frame rate (30), the number of frames in the video, the visual style, format and resolution. Click the Preview button to see the result, and if you are happy hit OK to start the rendering. This may take up to a minute depending on the scene's complexity and frame settings. A WMV file is the result, which will play in Windows Media Player. It's best to make the initial test renders low quality and resolution, and gradually build up the textures to a final production level movie which can take a couple of hours to render.
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.