CHAPTER 17

Rendering and Materials

After developing a 3D model, you'll usually want to apply materials and render it to get a better feel for the substance of the project so that you can produce a clearer presentation for clients.

In this chapter, I'll give you a quick tour of some of these rendering steps as you set up a view of the cabin and render it. Developing a full rendering takes time and patience, but touching on a few of the many steps involved will give you a feel for the process. You've put in a lot of time working your way through this book, and you deserve to have a rendered 3D view of your cabin to complete the process. Be aware, however, that rendering is computationally intensive and can task your computer pretty heavily. It's a good rule to save your file prior to each rendering attempt.

In this chapter, you will learn to

• Use the Loft tool
• Create cameras to reproduce views
• Create a lighting scheme
• Enable and control shadow effects
• Choose the background
• Assign materials to surfaces
• Adjust mapping and tiling
• Save setup views and lights as restorable scenes
• Render and output to a file

Creating Cameras to Reproduce Views

Similar to saving named views in Chapter 10, “Generating Elevations,” using cameras is a method for returning to a saved viewpoint. The most significant advantage of cameras is the ability to select the camera object and change its position or orientation, rather than panning or zooming in the drawing area. Cameras can also be animated to show your model from a variety of locations. Before you place the cameras, however, you'll create some land on which your cabin will sit, so that it no longer appears to be floating in the air.

Using the Loft Tool

The Loft tool builds 3D geometry in one of three ways: by connecting a series of 2D shapes, called contour lines, with 3D surfaces; by extruding a cross section along a path; or by controlling the transition between two cross sections with 2D guide curves. You'll use the first method to create a loft object to serve as the land by drawing concentric 3D polylines, converting them to splines, changing their elevations, and then lofting them. Follow these steps:

1. With I16C-SPLAYO.dwg (M16C-SPLAYO.dwg) as the current drawing, change to the Wireframe visual style with the in-canvas viewport controls, and zoom in to the cabin.
2. Make a new layer named C-TOPO-3DOB, assign it color 94, and set it as the current layer.
3. Freeze all the other layers except A-DECK-STRS-3DOB and A-FNDN-3DOB.
4. Start the Rectangle (RECTANG) command, and draw a closed polyline around the perimeter of the base of the foundation, as shown in Figure 17.1.

   Because each contour you'll draw will have a constant elevation, you'll use a standard polyline instead of a 3D polyline. Standard polylines can have only a single elevation, whereas 3D polylines can have many elevations.

5. Use the Endpoint osnap to snap to opposite vertices at the bottom corners of the foundation.
6. Use the Polyline (PLINE) command to draw another closed polyline around the concrete support posts, snapping the outside corner of each, and the outside corners of the stringers (see Figure 17.1).

   You can pick an interim point between each of the long sides of the cabin to break up the perimeter. These are the first two contour lines.

7. Switch to the Insert tab, and then choose the Insert tool found on the Block panel to insert the I17-PropBndy.dwg (M17-PropBndy.dwg) file.

   

   FIGURE 17.1 Draw the first two 3D polylines around the cabin.

8. Insert the drawing by using the 0,0,0 insertion point, a uniform scale of 1, and a rotation of 0 degrees.
9. Finally, be sure that the Explode check box is selected in the lower-left corner of the Insert dialog box.

   If you haven't already, visit the companion website found at www.sybex.com/go/autocad2013ner or www.thecadgeek.com to access the Chapter 17 download, which includes the I17-PropBndy.dwg (M17-PropBndy.dwg) file.

10. Turn off Ortho mode or Object Tracking if they are on; then click the TOP face of the ViewCube to switch to a top view.
11. Continue using the PLINE command to draw two more oddly shaped, closed polylines between the cabin and the property line.
12. Change the layer of the inserted property line to the C-TOPO-3DOB layer (see Figure 17.2).
13. Click the Edit Polyline button from the extended Modify panel on the Home tab, or enter PEDIT. Enter M to choose the Multiple option.
14. Select the two polylines between the cabin and the property line.
15. Click the Spline option in the context menu, as shown in Figure 17.3, to change the polylines into curved splines and then click .

FIGURE 17.2 Draw two more polylines between the cabin and the property line.

FIGURE 17.3 Select Spline from the context menu.

The last three contour lines you drew are at the same level as the top of the foundation. You need to move them downward to define the slope of the property away from the cabin:

1. Switch to an isometric view by selecting a corner of the ViewCube.
2. Use the 3D Move (3DMOVE) tool found on the Home tab Modify panel, and then move the spline closest to the cabin foundation down 3′-6″ (1070 mm) in the negative Z direction.
3. Repeat the 3DMOVE command, moving the spline closest to the property line down 4′-4″ (1320 mm) and then moving the polyline that follows the property line down 5′-4″ (1625 mm).

   This should provide a gentle slope for the land.

4. Select the Front or Left face of the ViewCube to view your model from the side, and verify that each of the contours are lower than the previous (see Figure 17.4).

   

   FIGURE 17.4 The contour lines as viewed from the side

5. Switch back to an isometric view, freezing all layers except C-TOPO-3DOB.
6. Click the Loft button in the Modeling panel on the Home tab.

   It may be hidden under the Extrude button.

7. At the Select cross sections in lofting order or: prompt, enter MO to set the creation mode.
8. Choose Surface by entering SU.

   The creation mode is changed to Surface, and the command line once again reads Select cross sections in lofting order or:.

   It's important to pick the cross sections for a lofted surface in order; otherwise, the surface may not generate as expected.

9. Press after you've selected each of the cross sections to advance through the LOFT command.

   Select the outermost polyline and then each subsequent spline or polyline in order, from outside to inside.

   You can adjust how lofted surfaces are created by entering S with the LOFT command still running.

10. Verify that the Smooth Fit option is selected in the Loft Settings dialog box that opens, shown in Figure 17.5.

    Smooth Fit creates a soft transition from one contour to the next.

11. At the Enter an option: prompt, enter C for the Cross Sections Only option.
12. Click OK, and then change to the Conceptual visual style.

    Your cabin land parcel should look similar to Figure 17.6.

    

    FIGURE 17.5 The Loft Settings dialog box

    

    FIGURE 17.6 The completed cabin land

13. Thaw all layers with a 3DOB suffix.
14. Save your drawing as I17-01-LoftedSurface.dwg (M17-01-LoftedSurface.dwg).

Creating the Cameras

AutoCAD^® software uses a camera analogy to define reproducible views. The cameras and their respective targets are placed in model space and, using several available grips, are adjusted to capture the desired view.

1. Continue using I17-01-LoftedSurface.dwg (M17-01-LoftedSurface.dwg), or open it if it's not already open.
2. Click the Render tab; then, on the Camera panel, click the Create Camera (CAMERA) button and move the cursor into the drawing area.

   A camera icon appears at the cursor location.

   TIP If you don't see the Camera panel, right-click the title bar of any panel and choose Show Panels Camera from the context menu.

3. Click near the edge of the land at a point southeast of the cabin, using the ViewCube as a guide, and then move the cursor again.

   Now the camera stays in place, as shown in Figure 17.7, and the target is moved with the cursor. The location of the target determines the orientation of the camera, and the visible cone emitting from the camera shows the camera's field of view (FOV), or the angle visible through the camera's lens.

   

   FIGURE 17.7 Placing a camera into the drawing

4. Turn off any running osnaps, and then click the middle of the deck to place the target.

   The camera disappears temporarily while AutoCAD waits for input at the cursor and the command line.

5. Enter N, or click Name, to activate the Name option.
6. At the prompt, enter Cam Southeast.

   The camera reappears in the drawing area.

7. Create another camera that views the cabin from the northwest corner of the property.
8. Place the target at the middle of the cabin, and name this camera Cam Northwest.

   You should always give your cameras descriptive names to make it easier to find the correct view when multiple cameras exist in a drawing. You can change the camera name in the Properties palette.

9. Use the ViewCube to change the current view to a viewpoint from the southeast and slightly above the cabin (see Figure 17.8).

   

   FIGURE 17.8 Viewing the cabin and cameras from above and to the southeast

10. Select the Cam Southeast camera.

    The Field of View cone and grips are displayed, and the Camera Preview dialog box opens. This dialog box displays the view from the camera in one of the available visual styles (see Figure 17.9). The 3D Wireframe visual style is the default and the one you will use here.

    

    FIGURE 17.9 Selecting the camera displays its grips and the Camera Preview dialog box.

11. Place your cursor over the grip at the center of the camera, and you will see a tooltip that reads Camera Location.
12. While the camera is selected, a 3D gizmo displays at the camera's origin. Click the z-axis (blue axis line), and then move the camera 5′ (1524 mm) up in the Z direction to about eye level.

    You may need to click the grip again for the Camera Preview dialog box to refresh.

13. Select the Camera Target grip, and move it 7′ (2130 mm) in the Z direction.

    Raising the target brings the cabin more into the preview window.

14. Press Esc to deselect the camera, and then select the Cam Northwest camera.
15. Move it 30′ (9150 mm) in the Z direction to get a higher view of the structure.
16. Next, adjust its view however you like by moving the square Target Location or triangular Lens Length/FOV grips.
17. Click the View Controls menu from the in-canvas viewport controls, and then Custom Model Views.

    Notice that the two cameras now appear in the list, as shown in the left image of Figure 17.10.

    

    FIGURE 17.10 The View Manager dialog box showing the two new cameras listed

    Alternatively, the list of custom model views is accessible from the View Manager dialog box (see the right side of Figure 17.10). Open this dialog box from the View tab Views panel.

18. Select Cam Southeast from the list, click the Set Current button, and then click OK.

    Your drawing area changes to view the scene from the selected camera, as shown in Figure 17.11.

19. Save your drawing as I17-02-CreateCameras.dwg (M17-02-CreateCameras.dwg).

Creating a Lighting Scheme

Without a well thought-out lighting scheme, the scene can look flat and unappealing. In this section, you will add a light to represent the sun and then an additional light to add ambient illumination to the scene.

FIGURE 17.11 The cabin as viewed through the Cam Southeast camera

Creating a Light Source

AutoCAD has four kinds of lighting, each with a distinct method for distributing light rays into the scene. They are as follows:

Point Light All light rays are emitted from a single location and diverge as they get farther away. An incandescent lightbulb is a real-world example of a point light, even though the light does not travel in the direction of the light's fixture.

Spotlight With this type of light, rays are emitted from a single point, but they are restricted to a conical portion of the amount of light that a similar point light would emit. Flashlights and headlights are examples.

Distant Light With this type of light, all light rays are parallel. Although the sun is technically a point light, at the enormous distance the light rays travel to Earth, they are nearly parallel.

Weblight These are photometric lights with real-world distributions. These lights can be used in conjunction with light distributions derived by manufacturers of real-world lights. Using manufacturer data to establish lighting distributions helps ensure more accurate representation of rendered lights than possible when using point or spotlights.

Each light type has a unique set of parameters. The sun is a special distant light and has its own settings, including determining the light's position based on the geographic location of the scene, the date and time, and the ability to add ambient light to the drawing.

To add this type of light, you'll use tools in the Visualize tab of the Ribbon:

1. Continue using I17-02-CreateCameras.dwg (M17-02-CreateCameras.dwg), or open it if it's not already open.
2. Click the Ribbon's Render tab.
3. In the expanded Lights panel, make sure the Default Lighting option is turned off.

   When it is off, the button will not have a blue background as the cursor pauses over it and there will be no default illumination in the scene.

4. In the Sun & Location panel of the Render tab, check the status of the Sun Status button.

   Be sure that it's toggled on by verifying that the button has a blue background.

5. Click the Sun Properties button at the right end of the Sun & Location panel to open the Sun Properties palette, as shown in Figure 17.12.

   The palette may be docked on the side of the AutoCAD window.

   

   FIGURE 17.12 Set the date in the Sun Properties palette.

6. In the Sun Angle Calculator rollout, set Date to 9/21/2012 and Time to 3:00 PM (see Figure 17.12).

   The date is set by clicking the button at the right end of the date field and choosing from a calendar.

7. In the Sun & Location panel on the Render tab of the Ribbon, click the Set Location button.
8. When the Geographic Location – Define Geographic Location dialog box appears, select Enter The Location Values as the method to define the location of the cabin drawing (see Figure 17.13).

   

   FIGURE 17.13 The Geographic Location – Define Geographic Location dialog box

   NOTE If you have Google Earth installed, you could have chosen to import a KML or KMZ file (Google Earth placemark files) or to import the location directly from Google Earth.

   The dialog box closes, and the Geographic Location dialog box opens (see Figure 17.14).

   You can define nearly any location in the world as the location for the current drawing by entering the latitude and longitude in this dialog box. For your cabin, you'll select the city in which it's located from a map.

9. Click the Use Map button in the top-right corner of the dialog box to open the Location Picker dialog box, as shown in Figure 17.15.

   

   FIGURE 17.14 The Geographic Location dialog box

   

   FIGURE 17.15 The Location Picker dialog box

10. In the Region drop-down list below the map, select the region that you prefer.
11. Below that, in the Nearest City drop-down list, select a city within that region.

    The example here uses North America and Richmond, VA. A red cross appears over Richmond (or wherever you've chosen) in the map. The Time Zone drop-down list displays the accurate time zone based on the location you selected (see Figure 17.15).

12. Click OK to close this dialog box. If a dialog box appears asking whether the time zone should be updated, click the Accept Updated Time Zone option.
13. Click OK to close the Geographic Location dialog box.
14. Save your drawing as I17-03-SetLocation.dwg (M17-03-SetLocation.dwg).

    TIP If a particular city is not listed, you can uncheck the Nearest Big City option and then click directly on the map to set the location or enter the longitudinal and latitudinal coordinates in the left side of the Geographic Location dialog box.

Enabling Shadows

Shadows add depth and realism to a scene and tie the objects to the surfaces on or near where they rest. You have significant control over the types of shadows cast by the lights in the drawing and whether those shadows appear in the viewports. You adjust how the shadows appear in the viewport and how they render in the Render tab.

When shadows are turned on, AutoCAD will render them by using one of three methods: simple, sorted, or segment. The simple method is the default used by AutoCAD, and it calculates shadow shaders in random order. By contrast, the sorted and segment methods each calculate shadows in the order they are cast, and they produce higher-quality renderings at the cost of machine performance. Segment shadows will produce the highest-quality rendering, but they take the longest time to complete.

To ensure that you'll be able to work through this chapter's exercise in a timely manner, we'll stick to the simple method. Don't be fooled by its name; while it doesn't perform the advanced calculations done by the sorted and segment methods, it still produces a detailed rendering without sacrificing system performance.

1. Continue using I17-03-SetLocation.dwg (M17-03-SetLocation.dwg), or open it if it's not already open.
2. In the Lights panel, click the down-arrow under the No Shadows icon and choose Full Shadows from the fly-out menu, as shown in Figure 17.16.

   

   FIGURE 17.16 Choosing the Full Shadows option

   This displays an approximation of the shadows in the viewport.

   WARNING The Full Shadows option requires that your video card utilize hardware acceleration. See the Display Backgrounds and Shadows page of the AutoCAD 2013 help file to determine whether your system is equipped with hardware acceleration.

3. Click the Advanced Render Settings button on the right end of the Render panel's title bar.
4. In the Advanced Render Settings palette that appears, scroll down to the Shadows drop-down list and make sure that Mode is set to Simple and Shadow Map is set to On (see Figure 17.17).
5. Close the Advanced Render Settings palette.

Creating the First Render

A rendering is the visual result of the program calculating the effects of the lights and materials on the surfaces in the drawing. Let's make a preliminary render now. Later, you'll add materials and a background and then render the drawing again.

1. Click the Render button on the Render panel.

   The Render window opens and, after a few moments, the rendering fills in the graphic area (see Figure 17.18). As you can see, the right side of the cabin is unlit and in total darkness.

   

   FIGURE 17.17 The Shadows settings in the Advanced Render Settings palette

2. Click the Point button in the Lights panel (it may be hidden under another light button), and then click to place the light on the ground about 20′ (6100 mm) northeast of the front deck.
3. Click the Name option in the context menu that appears at the cursor and give the light the name Northeast Ambient.

   As with cameras, you should give your lights descriptive names.

4. Double-click the light to open its Properties palette, and make the following changes:

   Position Z: 30′ (9150)

   Shadows: Off

   Intensity Factor: 60.000

   Lamp Intensity: 15,000 Cd

   

   FIGURE 17.18 The first cabin rendering in the Render window

5. Click the down-arrow in the Filter Color field, and then choose Select Color.
6. In the Select Color dialog box that appears, change the Color Model to RGB, and enter 252, 250, 212 in the Color field, as shown in Figure 17.19.

   This gives the light a pale yellow hue.

7. Click OK to close the Select Color dialog box, and close the Properties palette.
8. Switch back to the Cam Southeast view if necessary, and render the scene again.

   As you can see in Figure 17.20, this time the shadows on the right side of the cabin are not as stark as they were previously; but the overall appearance is still pretty dark. You need to add some ambient light.

   

   FIGURE 17.19 The properties for the point light

   

   FIGURE 17.20 The cabin rendering after adding the second light

9. Open the Advanced Render Settings palette again, and then click the lightbulb icon next to Global Illumination in the Indirect Illumination drop-down list (see Figure 17.21).

   

   FIGURE 17.21 Turning on Global Illumination

   This will add a measure of ambient light to your scene without washing it out.

   This rendering looks a bit better than the last. The Render window maintains a history of the recent renderings, and you can compare them by clicking any of the renderings listed in the pane at the bottom of the Render window. To delete a rendering, follow these steps:

   1. Select it.
   2. Right-click it.
   3. Choose Remove From The List.

   You can continue to tweak the lighting as you want. For indoor projects that require rendering, a good rule of thumb is to expect to dedicate 15 to 25 percent of the total project time to creating an excellent lighting scheme. For outdoor scenes, dedicating 5 to 10 percent should be sufficient.

10. Save your drawing as I17-04-FirstRender.dwg (M17-04-FirstRender.dwg).

The building looks fine, but it would be nice to have something in the background other than the blank screen, and the lights need to be tweaked.

Controlling the Background of the Rendering

Some of the options you can set when choosing a background for the rendering are as follows:

The AutoCAD Background This is what you used for the preliminary rendering.

Another Solid Color Use the slider bars to choose another solid color.

Gradient You can use varying colors (usually light to dark) blended together.

Image You can supply or choose a bitmap image.

Sun & Sky Background You can use a computer-generated sky. This background has the option of introducing additional ambient illumination into the scene.

You'll use the Sun & Sky Background option with the Illumination option here:

1. Continue using I17-04-FirstRender.dwg (M17-04-FirstRender.dwg), or open it if it's not already open.
2. Click the View tab, and then click the Named Views button in the View panel to open the View Manager dialog box.
3. Expand the Model Views entry, and then select Cam Southeast.
4. Expand the drop-down list for the Background Override entry in the General rollout, and then choose Sun & Sky, as shown in Figure 17.22.

   

   FIGURE 17.22 The Cam Southeast camera selected in the View Manager dialog box

   Doing so opens the Adjust Sun & Sky Background dialog box, as shown in Figure 17.23.

   

   FIGURE 17.23 The Adjust Sun & Sky Background dialog box

   NOTE The sky background options are available only when the lighting units are not set to generic. This is controlled by the LIGHTINGUNITS system variable. Enter LIGHTINGUNITS 2 to set the lighting units to International. A setting of 1 sets the lighting units to American, and 0 sets them to generic units.

5. In the Sky Properties rollout, change the Intensity Factor value to 3.
6. Expand the Status drop-down list, and choose Sky Background and Illumination (see Figure 17.23).
7. Click OK to close the Adjust Sun & Sky Background dialog box.
8. Click Set Current in the View Manager dialog box, and then click OK to close it.
9. Open the Advanced Render Settings palette from the Render tab's Render panel.
10. Scroll down to the Final Gather rollout, and make sure the Mode is set to Auto or On.

    Background Illumination will not work if Final Gather Mode is set to Off.

11. Save your drawing as I17-05-RenderBackground.dwg (M17-05-RenderBackground.dwg).
12. Render the scene.

It will take a little longer to process this image, and you'll notice that the image in the Render window is replaced twice—the first time with a very rough-looking representation of the cabin and then again with a sharper result. When it is done, the display in your Render dialog box should look similar to Figure 17.24. The background image not only appears behind the cabin and ground, but it also contributes light to the scene.

FIGURE 17.24 The cabin rendered with the Sun & Sky background and additional illumination

Adding Materials

Adding the proper materials to a scene can greatly increase the realism of the drawing and convey a better sense of size and texture to the person viewing the image. This chapter assumes that you installed the material library that ships with AutoCAD 2013, along with the rest of the package.

You can assign materials to your drawing objects from several premade libraries, you can create materials from scratch, or you can edit materials that originate from the libraries. In the next exercise, you will apply materials from the AutoCAD libraries:

1. Continue using I17-05-RenderBackground.dwg (M17-05-RenderBackground.dwg), or open it if it's not already open.
2. Click the Render tab, and then click the Materials Browser button in the Materials panel to open the Materials Browser palette, shown in Figure 17.25.

   The Materials Browser palette is divided into two primary areas:

   Document Materials The upper region of the Materials Browser palette displays the materials that have been loaded into your current drawing. Above the name for each material, a small thumbnail preview of the material displays.

   Libraries AutoCAD materials are filed away into a series of libraries. A list of available libraries along with the material categories within each library display along the left side of the palette. Selecting any library or category on the left will display the materials belonging to that library or category as a series of thumbnails along the right side of the palette. The default installation creates two libraries: the Autodesk Library and the My Materials Library.

   Materials may be added to the current drawing from any of the libraries listed in the lower portion of the Materials Browser.

   

   FIGURE 17.25 The Materials Browser palette

   DISPLAY MATERIAL THUMBNAILS

   Because materials are inherently visual, many users find the Thumbnail View type to be more useful than the default List View type. You can change this by using the panel display button and selecting Thumbnail View beneath the View Type heading.

   

3. If it's not open already, expand Autodesk Library in the Libraries portion of the Materials Browser.

   A list of categories containing an assortment of materials displays.

4. Browsing the Flooring category, locate and then select the Red Oak - Wild Berries material on the right side of the Materials Browser palette.

   The Red Oak - Wild Berries material is added to the Document Materials list at the top of the Materials Browser palette.

5. Repeat steps 3 and 4 to load the materials listed here:

   Category	Material Name
   Wood	Hardwood
   	Yellow Pine - Natural No Gloss
   Brick	12in Running - Burgundy
   Glass	Blue Reflective
   Metal Aluminum	Satin - Brushed
   Sitework	Grass - Dark Bermuda
   Siding	Shakes - Weathered
   Roofing	Shingles - Asphalt 3-Tab Black
   Wall Paint	Flat - Antique White

All of the materials you'll need for your cabin are now loaded into the current drawing. However, before those materials are used for rendering, they must be assigned to objects in your drawing. Materials can be applied to individual objects, faces, or layers. Whenever possible, it's best to assign materials to an entire layer as opposed to individual objects or faces. Subscribing to this practice will help ensure the manageability of your model.

To assign materials to the layers in your drawing:

1. If you haven't already, switch to the Render tab and then expand the Materials panel to select the Attach By Layer tool.

   The Material Attachment Options dialog box opens to display a list of materials and layers in the current drawing.

   The Material Attachment Options dialog box, shown in Figure 17.26, is split into two parts:

   

   FIGURE 17.26 The Material Attachment Options dialog box

   • The left side displays a list of materials loaded into the current drawing.
   • The right side displays a list of layers in the current drawing.

   By default, the Global material is assigned to each layer.

2. Locate the Red Oak - Wild Berries material on the left side of the dialog box and the A-DOOR-3DOB layer on the right.
3. Drag the Red Oak - Wild Berries material from the left side of the dialog box onto the A-DOOR-3DOB layer on the right.
4. Verify that the material was applied by checking the Material column in the Layer list on the right side of the dialog box.
5. Repeat this procedure by assigning materials to each of your 3DOB layers, as shown on the next page.

   Layer	Material
   A-DECK-3DOB	Yellow Pine - Natural No Gloss
   A-DECK-STRS-3DOB	Yellow Pine - Natural No Gloss
   A-DOOR-THRE-3DOB	Satin - Brushed
   A-FLOR-3DOB	Hardwood
   A-FNDN-3DOB	12in Running - Burgundy
   A-GLAZ-3DOB	Blue Reflective
   A-GLAZ-SILL-3DOB	Yellow Pine - Natural No Gloss
   A-ROOF-3DOB	Shingles - Asphalt 3-Tab Black
   A-ROOF-DECK-3DOB	Flat - Antique White
   A-WALL-EXTR-3DOB	Shakes - Weathered
   A-WALL-INTR-3DOB	Flat - Antique White
   C-TOPO-3DOB	Grass - Dark Bermuda
   Created in earlier exercises:
   A-DOOR-3DOB	Red Oak - Wild Berries

6. Save your drawing as I17-06-RenderMaterials.dwg (M17-06-RenderMaterials.dwg).
7. Render your drawing one more time.

It should look like Figure 17.27. Notice how the roof is reflected in the living room window.

FIGURE 17.27 The cabin rendered with materials applied to the remaining 3D objects

Adjusting the Material Mapping

Image maps are the components of a material that consist of image files, such as a JPEG or TIFF. When a material uses an image map, its purpose can be to change the color of an object (diffuse maps), to give the illusion of texture (bump maps), or to define the transparency of a surface (opacity maps).

Adjusting the Map Size

The individual properties of all materials are controlled in the Materials Browser palette. Here you'll find the controls for setting the parameters for the size of the map, which map to use, and several other features for the selected material.

1. Continue using I17-06-RenderMaterials.dwg (M17-06-RenderMaterials.dwg), or open it if it's not already open.
2. In the Render tab, click the Materials Browser button in the Materials panel.
3. In the Document Materials portion of the Materials Browser palette, hover over the Shakes - Weathered material and click the Edit (pencil) icon.

   The Materials Editor palette opens to display details about the Shakes - Weathered material (see Figure 17.28).

   

   FIGURE 17.28 The Materials Editor palette with the Shakes Weathered material selected

4. From the Materials Editor, click the photographic image found under the Generic group (see Figure 17.28).

   Selecting the image in the Materials Editor palette will open the Texture Editor palette, shown in Figure 17.29.

5. Expand the Transforms group and then the Scale group to locate the Sample Size setting.
6. Enter 2′-4″ (710 mm) into the Height text box.

   Note how the dimensions shown in the preview at the top of the Texture Editor palette update to reflect this change.

7. Close the Texture Editor, Materials Editor, and Materials Browser palettes, and then change your visual style to Realistic.

   The Realistic style displays the materials and maps, and the changes that you make to them, all at the expense of system performance (see Figure 17.30). You should use this visual style only when necessary.

8. Save your drawing as I17-07-AdjustMaterial.dwg (M17-07-AdjustMaterial.dwg).

FIGURE 17.29 Modifying the material scale from the Texture Editor palette

FIGURE 17.30 View of the cabin using the Realistic visual style

Adding Texture

The exterior walls of the cabin consist of flat surfaces, and there are no features that would cause shadows to be cast. The Bump Map option adds apparent texture by adding shadows where they would appear if the surfaces had texture. In the Maps rollout, you can see that only the Diffuse Map option is checked, meaning that no map is used to define the opacity and bump features of the material. Opacity maps and bump maps don't use any of the color information from an image map, but this doesn't mean that color maps can't be used—only that the grayscale equivalent of the colors will be interpreted by AutoCAD.

1. Continue using I17-07-AdjustMaterial.dwg (M17-07-AdjustMaterial.dwg), or open it if it's not already open.
2. Open the Materials Editor palette once again by locating the Shakes Weathered material in the Materials Browser palette.
3. Select the check box next to the Bump group heading in the Materials Browser.
4. In the Bump area, click the Select Image button to open the Select Image File dialog box. It should open to the following directory:

   Windows 32-Bit C:Program FilesCommon FilesAutodesk SharedMaterialsTextures3Mats

   Windows 64-Bit C:Program Files (x86)Common FilesAutodesk SharedMaterialsTextures3Mats

   Navigate to one of these directories if the Image File dialog box does not automatically open there.

5. Select the Thermal - Moisture.Shakes.Weathered.jpg file, the same file used as the diffuse map, and then click Open.

   The Thermal - Moisture.Shakes.Weathered.jpg image is also included in the Chapter 17 download.

6. Move the Bump Amount slider to 10 (see Figure 17.31).

   Figure 17.32 shows the cabin rendered with the new material parameters.

7. Adjust the mapping and materials for the remaining objects, and then save your file as I17-08-MaterialTexture.dwg (M17-08-MaterialTexture.dwg).

There are enough tools and features relating to AutoCAD materials to fill several chapters, and this was just an introduction. Some of the features not covered are copying mapping between objects, applying different maps to different surfaces of the same object, and using opacity maps. I strongly encourage you to investigate the full capabilities of the AutoCAD materials.

FIGURE 17.31 Changing the amount of bump applied to a material

FIGURE 17.32 The cabin with the new material parameters

Rendering to a File

By default, the Render feature creates a rendering in the Render dialog box only. The picture is not saved unless you explicitly tell AutoCAD to save it. You can also instruct the program as to the quality level of the rendering and the size, in pixels, of the image created. Follow these steps:

1. Continue using I17-08-MaterialTexture.dwg (M17-08-MaterialTexture.dwg), or open it if it's not already open.
2. Switch back to the Conceptual visual style and the Cam Southeast view.
3. From the Render tab's Render panel, click the Render Output File button and then the Browse For File button to open the Render Output File dialog box.
4. Navigate to the folder where you want to place the new image file, and then select a supported image file type in the Files Of Type drop-down list. For this exercise, do the following:
   1. Choose TIF as the file type.
   2. Name the file Cabin Rendering Small.tif (see Figure 17.33).

   

   FIGURE 17.33 Saving the final cabin rendering

5. Click the Save button.

   Depending on the file type you choose in the future, an Options dialog box, similar to the one shown in Figure 17.34, will appear.

   

   FIGURE 17.34 The TIFF Image Options dialog box

6. In the TIFF Image Options dialog box, select 24 Bits (16.7 Million Colors), make sure the Compressed option is checked, and then click OK.

   The next time you render the drawing, the rendering will be saved as an image file on your hard drive, and the filename will appear in the Output File Name column of the Render window, with a folder and check mark next to it (see Figure 17.35). The files with clocks and teapots won't be saved, but you can open them in the Render window by clicking the appropriate filename.

   

   FIGURE 17.35 The saved file shown at the bottom of the Render window

7. In the AutoCAD window, expand the Render Presets drop-down list and select Presentation, as shown in Figure 17.36.
8. Expand the Render panel, expand the Render Output Size drop-down list, and then choose Specify Image Size (see Figure 17.37) to open the Output Size dialog box.
9. In the Output Size dialog box (see Figure 17.38), set Width to 2000 and Height to 1600, and then click OK.

   

   FIGURE 17.36 Choose the Presentation rendering preset.

   

   FIGURE 17.37 Set the output size.

   

   FIGURE 17.38 The Output Size dialog box

   This is the resolution required to print a 10″×8″ image at 200 dots per inch (dpi).

10. Click the Browse For File button to open the Render Output File dialog box.
11. Name this file Cabin Rendering Large.tif, and make it a 24-bit TIF file at 200 dpi. Click OK.
12. Save your drawing and then click the Render button again and wait a while as the new image renders.

    With the higher quality and larger image size, this may take considerably longer to process.

13. When the rendering is completed, look at the file size in Windows Explorer and then compare the two images in your image-viewing software. The larger file is much crisper than the smaller image at the expense of increased rendering time.

This has been a brief introduction to the world of 3D and rendering in AutoCAD, but you should now be oriented to the general way of doing things and have enough tools to experiment further. For a more in-depth discussion of the process, including rendering, see Mastering AutoCAD 2013 and AutoCAD LT 2013 by George Omura (Wiley, 2012), or visit the companion site for this book at www.sybex.com/go/autocadner2013 and www.thecadgeek.com.

If You Would Like More Practice…

Renderings can be an invaluable way both to explore and validate design alternatives. For more practice working with materials as a way of design validation, you can try the following:

• Experiment with different materials for the exterior of your cabin.
• Create an additional camera to explore your cabin from another vantage point.
• Render your cabin with new materials applied to the scene.

Are You Experienced?

Now you can…

• Create a loft object by using contour lines
• Create and manipulate cameras
• Add sunlight to a scene
• Place a point light
• Specify a scene's real-world location
• Assign materials to the objects in a drawing
• Adjust mapping and tiling
• Render a drawing, and save the result as an image file