Reducing Rendering Time for Quick Studies

At times, you will be rushing to finish a rendering and won't want to wait for each trial rendering to become visible. Several AutoCAD tools can save you time by limiting the resolution or area being rendered. Suppose you want to render just the area where you've added a tree to make sure it is in the right location.

The following exercise will show you how this is done:

1. Choose View   Named Views and then restore the 3DFront view.

2. Open the Render dialog box and set the Destination option to Viewport.

3. Click the Crop Window check box to activate this option and then click the Render button.

4. The prompt Pick crop window to render: appears. Select the area shown in Figure 17.33, indicated by the rubber-banding square. After you select the window, AutoCAD renders only the area you selected.

   
   Figure 17.33: Selecting the crop window

The Crop Window option is a working tool and is not available when File or Render Window is selected as the destination.

You can also select specific objects to be included in the rendering by selecting the Query For Selections check box in the Render dialog box. This option asks you to select a set of objects before it proceeds to render. You can render to all three destination options with Query For Selections turned on.

If you want to check composition by using a quick rendering with a reduced resolution, you can use the Sub Sampling drop-down list. Try the following exercise to see how it works:

1. Open the Render dialog box and then open the Sub Sampling drop-down list.

2. Choose 3:1 from the list, make sure the Crop Window option is not selected, and then click the Render button. Your view will render faster but will look a bit crude (see Figure 17.34).

   
   Figure 17.34: A rendered view with the Sub Sampling option set to 3:1

The different ratios in the Sub Sampling option tell you how many pixels are being combined to reduce the resolution of the image. For example, 3:1 combines three pixels into one to reduce the resolution to a third of the original.