Rendering the Shadow Element

So far you have rendered only the objects themselves, but none of the shadows. Instead of rendering shadows on each object, it is more efficient to render the shadows all together in a single image that you can later composite in Photoshop. This way, you'll have global control over the shadows by being able to change the opacity of the shadow image layer.

In VIZ, you must first turn on shadow casting in at least one light source. You can then render the shadows in a separate pass by using the Render Elements feature. Let's see how this works:

1. Open the Select Objects dialog box (press H). In the List Types group, click the None button to deselect all categories. Then check Lights to display a listing of all the objects of this category. Double-click Direct Light to select this object and close the dialog box.

2. Click the Modify tab of the Command Panel. In the General Parameters rollout, check On in the Shadows group. Make sure Ray Traced Shadows is selected in the drop-down list box if it's not already.

TIP Ray traced shadows are the most accurate casting algorithm, and they show crisp edges.

3. Open the Render Scene dialog box (press F10). Click the Render Elements tab. Click the Add button and select Shadow from the list of elements (if not already present). Make sure Enable is checked.

4. Click the Browse button in the Selected Element Parameters group. In the Render Element Output File dialog box, navigate to the folder in which you stored your rendered images from the last section. The filename will automatically be Shadow.tga (see Figure 7.18); click OK.

5. Click the Render button at the bottom of the Render Scene dialog box. An RFW appears, and the building progressively appears in color as the scan lines are rendered. After the first rendering is complete, a second Shadow window appears. The shadow is completely black in RGB. You'll have to view the alpha channel to see the shadows against the black background. Click the Display Alpha Channel button in the RFW toolbar, as shown in Figure 7.19.

6. You don't have to save the shadow rendering manually because Render Elements did that automatically for you. Close both rendered frame windows. You are done with the 3D part of the tutorial because all the necessary images have been rendered. Exit VIZ without saving the scene.

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Responses

  • haiduc
    HOW TO SHADOW AN ELEMENT IN ACAD?
    8 years ago
  • giacinta
    How to show shadow on cad drawings?
    8 years ago

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