Page 291 - Enhancing CAD Drawings with Photoshop

4386.book Page 275 Monday, November 15, 2004 3:27 PM

INTEGRATING AND PAINTING IN PHOTOSHOP 275

Masking and Painting Surfaces
Now that all the renderings from VIZ have been integrated into a working Photoshop document, you
are ready to start masking and painting. This tutorial must follow a particular sequence of steps to be
useful. However, I encourage you to experiment and play as you illustrate; make up your own steps
once you get a feel for it. Don’t be afraid to throw layers away and try different combinations of
masks, colors, brushes, and brush strokes to get what you are looking for.

Masking with Channels
In the following steps, we’ll use the special channels pasted into the document in the previous section
to make selections. Often the ObjectID and Normal channels are both used to select a particular sur-
face that you’d like to protect with a mask. The selection is then converted to a masked layer, ready
to receive paint. You’ll mask a couple of layers manually before saving an action that automates some
of the prep work to save time.
1. If you have Farmhouse.psd open from the previous exercise, you can continue here; if not,
open it from your hard drive before continuing. This file is also provided on the companion CD
if you are jumping in here.
2. Click the Layers palette if it is not already selected. Toggle the Shadow and Tree layers off by
clicking their eye icons. Select the Farmhouse layer. Create a layer set by clicking the Create A
New Set button at the bottom of the Layers palette, and rename the new set to Walls.
Select one of the wall surfaces in the tower using the Normal channel.
3. Click the Channels palette. Select the Normal channel or press Ctrl+6. Press W to select the
Magic Wand tool. On the Options bar, click the New Selection Mode button, type 20 into the
Tolerance text box, and check Anti-aliased and Contiguous. Clear the Use All Layers option.

4. Click a point inside the tower wall, as shown in Figure 8.21. The marching ants appear on the
selected wall surface.
Notice that part of the window is selected. We can subtract these areas from the selection using
the information contained in the ObjectID channel.
5. Press Ctrl+5 to select the ObjectID channel. Click the Subtract From Selection button on the
Options bar.

6. Click inside the window and shutter area that is within the current selection. You’ll have to
click three times to remove each shutter and the glass from the selection (see Figure 8.22).