Rendering in AutoCAD? Yes! David Cohn

Transcription

1 December 2-5, 2003 MGM Grand Hotel Las Vegas Rendering in AutoCAD? Yes! David Cohn Code VI21-1 Learn how to convert 3D drawings into finished, professional-looking renderings using the tools already built into AutoCAD software. This session covers all AutoCAD lighting, materials, landscaping, and other rendering commands. We'll take a typical architectural model and create finished photorealistic images of the building in both daylight and night settings. About the Speaker: David has more than 20 years of hands-on experience with AutoCAD as a user, developer, author, and consultant. He is the publisher and editor-in-chief of Engineering Automation Report, the former senior editor of CADalyst magazine, and the author of more than a dozen books about AutoCAD. A licensed architect, David has also developed numerous AutoCAD add-on programs and is a well-known speaker and industry consultant. david@dscohn.com

2 Rendering in AutoCAD? Yes! Rendering in AutoCAD? Yes! AutoCAD s rendering tools enable you to create photo-realistic images of your AutoCAD 3D models. Beginning with AutoCAD 2002, you can display models with realistic materials and lighting using AutoCAD s 3DORBIT command (you must first enable the Render options in the 3D Graphics Display properties by selecting Tools>Options>System>Properties). But this won t provide the level of detail possible using AutoCAD s RENDER command, because the following are not shown: Shadows 3D textures Bump maps Reflection Refraction To create truly realistic images, you must render them. With AutoCAD s rendering tools, you can add multiple light sources, assign materials to the objects in your drawing, and add people and landscaping to make your images look even more realistic. Rendering is often the most time-consuming aspect of a project. Because of the subtleties involved, you can spend a lot of time adjusting the lighting and materials. You may spend considerably more time creating a rendering than you spend actually building the 3-D model. In addition, when you work with multiple light sources, each of which casts shadows, the computer calculations alone require a considerable amount of computer horsepower. For that reason, AutoCAD s rendering tools let you render just a portion of the image, to test your changes prior to creating a final, full-screen rendering. The process of creating a computerized rendering involves four steps: Create the actual model Place lights Attach materials to objects in the drawing Render the image Other than creating the model, these procedures are conceptual rather than discrete sequential steps, and often are performed in an iterative process. For example, you may place some lights and create a test rendering. Then, after viewing the results of your test, you may change some of the lights and render the image again. Note: Renderings can be displayed in True Color by selecting the True Color Raster Images and Rendering check box on the Display tab of the Options dialog box. When selected, AutoCAD displays raster images and renderings at their optimum quality, as determined by the operating system. The Display Properties Settings in Windows must also be configured to True Color in order for AutoCAD to display True Color images and renderings. Note that increasing the number of system display colors can decrease display performance, while clearing the True Color setting in AutoCAD or reducing the color palette in the system display setting optimizes performance. Controlling Rendering You control the actual rendering process by using the Render dialog box. 2

3 Insert Class Title as per Title Page The Render dialog box contains numerous controls that enable you to determine the rendering type, options, procedures, destination, and so on. Selecting the Rendering Type AutoCAD actually produces one of three different types of renderings. In addition, independent developers can create other rendering processes that may be added to those provided by AutoCAD. You select the rendering type by choosing it from the Rendering Type drop-down list: Render Fastest. Produces a flat, shaded image quickly (the basic AutoCAD rendering option). Surfaces are shaded based on their AutoCAD color. Photo Real Produces photorealistic scanline images. This process is more time-consuming but can include 3D textures, opacity maps, and can simulate shadows cast by the various light sources. Photo Raytrace Produces the most realistic images. Ray tracing calculates theoretical rays of light that extend from the current viewpoint into the model. AutoCAD s most time-consuming rendering process, ray tracing can generate realistic reflection, refraction, and more precise shadows. Choosing the Scene The Scene to Render list contains the names of any previously saved scenes. When you create a rendering, you can save the viewpoint and a list of lights as a scene, which enables you to use a single drawing file to produce many different renderings. To render a specific scene, you simply select it from the list. You create scenes by using the SCENE command. You ll learn more about creating scenes later. Selecting Rendering Options The Rendering Options list contains numerous settings that let you fine-tune the rendering process: Smooth Shade Smoothes out the rough edges of multifaceted surfaces. AutoCAD then blends colors across two or more adjacent faces. You will almost always want to select this option. Apply Materials Applies materials attached to objects when producing the rendering. When this check box is not selected, all objects are assigned the color and material values defined for the *GLOBAL* material. This check box must be selected to see the materials that you attach to objects. Shadows Causes AutoCAD to generate shadows when using the Photo Real or Photo Raytrace rendering types. Calculating shadows is probably the most time-consuming part of generating a rendering. When you re just trying out different lights and materials, you can speed things along by turning off this option. Render Cache Causes AutoCAD to save rendering information to a cache file on the hard disk. As long as the drawing geometry or view remains unchanged, the cache file will be used 3

4 Rendering in AutoCAD? Yes! for subsequent renderings, eliminating the need for AutoCAD to recalculate the tessellation lines. Selecting this option can be quite a time-saver, particularly when rendering solid objects. Controlling Faces When you click the More Options button, AutoCAD displays a Render Options dialog box that is specific to the rendering type currently selected. The controls in this dialog box can be used to finetune the actions of the selected rendering type. Although you generally don t need to adjust these settings, depending on how your 3-D model was created, the Face Controls settings can save a considerable amount of time when you create renderings. A large portion of AutoCAD s calculation involves removing surfaces hidden behind others. AutoCAD removes these surfaces before rendering, because rendering the hidden surfaces would be a waste of time. In addition, surfaces have both a front and back side, and AutoCAD normally determines which is the front side of a surface, based on the direction in which its vertices are drawn. Depending on how you construct your model, you may not need AutoCAD to consider the back sides of surfaces at all. When you select the Discard Back Faces check box, AutoCAD ignores the back faces of all 3-D solid objects when it calculates a rendering, thus speeding up the entire rendering process. You should select this option only if you know for sure that none of the back faces need to be included in the rendering. The Back Face Normal Is Negative check box is usually selected. This tells AutoCAD that the side of the face whose vertices are drawn counterclockwise is to be considered the front face. If you clear this check box, AutoCAD reverses the side of the face considered to be the front face. Because AutoCAD, and most add-on programs, create objects such that their vertices are drawn counterclockwise, you should normally leave this check box alone. Caution: You should always make sure to draw faces in a consistent manner. Mixing faces drawn counterclockwise and clockwise in the same model can produce displeasing renderings. Selecting Rendering Procedures The check boxes in the Rendering Procedures area of the Render dialog box enable you to control what happens when AutoCAD begins the actual rendering process: Query for Selections If selected, when you start the actual rendering procedure, AutoCAD prompts you to select the objects to render. This lets you produce quick test renderings to see how a material looks on a particular object. Crop Window If selected, when you start the actual rendering procedure, AutoCAD prompts you to specify the corners of an area of the screen to be rendered. This lets you produce quick test renderings on a small portion of the drawing. Skip Render Dialog If selected, the next time that you start the RENDER command, AutoCAD immediately renders the current view without first displaying the Render dialog box. Tip: The preceding option seems to prevent you from ever turning off the option again, because you no longer see the Render dialog box when you use the RENDER command. However, the Render Preferences dialog box contains all the same controls as the Render dialog box. When the Skip Render Dialog check box is selected, you can use the Render Preferences dialog box to turn off this option, so that the Render dialog box again is displayed when using the RENDER command. Selecting the Rendering Destination This drop-down list enables you to control the destination of the rendering. It offers three options: Viewport Renders the image to the current AutoCAD viewport. Render Window Renders the image to a separate window called the Render Window. 4

5 Insert Class Title as per Title Page File Saves the rendering to a file. When you select this option, you can then click the More Options button to control the type of file, its resolution and color depth, and other settings. Tip: To create high-resolution images, save your rendering to a file. In previous versions of AutoCAD, if you wanted to include an image of the rendering on a composite paper space drawing sheet, you first needed to save the rendering to a file and then attach that image file to the drawing. In AutoCAD 2004, you can have AutoCAD render a layout viewport during plotting or publishing (DWF file creation), similar to removing hidden lines. But this adds time during plot creation. It s faster to render to a file and then insert the resulting raster image into your layout (<2 seconds vs. 17 seconds on a typical test drawings). Controlling Sub Sampling The Sub Sampling drop-down list enables you to reduce rendering time at the expense of image quality, while retaining effects such as shadows. Sub Sampling renders only a fraction of all the pixels. A sub sampling ratio of 1:1 renders all the pixels in the image, thus yielding the highestquality results. A ratio of 8:1 yields the fastest rendering speed by rendering only 1 out of every 8 pixels. Controlling Other Rendering Options The Render dialog box contains several other controls, some of which you can usually ignore, and two of which you ll learn more about later. The Background and Fog/Depth Cue buttons display the Background and Fog/Depth Cue dialog boxes, respectively. These dialog boxes can also be displayed by using the BACKGROUND and FOG commands. The Light Icon Scale setting simply determines the scale factor used to display the special light blocks that are inserted into the drawing when you add a light source. Although these blocks are visible in the drawing, they do not appear in renderings, and changing this value has no effect on the rendering at all. The Smoothing Angle sets the angle at which AutoCAD interprets an edge. If two surfaces meet at an angle less than this value, AutoCAD smoothes the transition between those surfaces. If the surfaces meet at an angle greater than this value, AutoCAD considers the transition to be an edge. The default value is 45 degrees. Depending on the 3-D model being rendered, you may need to adjust this value. Tip: If you want to cancel a rendering in progress for any reason, press the ESC key. Working with Lights Placing lights in your model begins to add a level of realism. The combination of carefully placed lighting and realistic materials quickly turns a flat, shaded image into a close approximation of reality. Controlling lights and materials is an iterative process, and you are likely to jump back and forth between the two, first adjusting the lighting, and then changing the way certain materials are attached. Lighting is discussed first. You add and configure lights by using the Lights dialog box. This dialog box is divided into two sections. The left side of the dialog 5

6 Rendering in AutoCAD? Yes! box lets you control individual lights. The right side of the dialog box controls the ambient light, which is the light that provides a constant illumination to every surface in the model. Ambient light does not come from any particular source and has no direction. Note: The first time that you add a light to the model, AutoCAD adds a new layer called ASHADE. AutoCAD stores all the lights on this layer as block objects. Controlling Ambient Light The controls on the right side of the dialog box determine the level of intensity and the color of the background light that provides constant illumination to all surfaces of the model. Ambient light alone can t produce a realistic image. Since all surfaces receive equal lighting, individual surfaces become indistinguishable from one another. You can use ambient light, however, to add just enough fill lighting to distinguish surfaces that are not directly illuminated by any of the individual light sources that you add to your model. You can adjust the intensity of ambient light either by moving the slider or by typing a value in the adjacent Intensity edit box. Ambient light intensity ranges from 0 (no ambient light) to 1 (full brightness). The sliders and adjacent edit boxes in the Color area let you adjust the red, green, and blue components of the ambient light. Click either the Select Color or Select Indexed button to display a Select Colors dialog box, in which you can select a color based on its AutoCAD Color Index (on the Index Color tab), adjust the color by using the hue, luminance, saturation (HLS) or red, green, blue (RGB) components (on the True Color tab), or select a color from one of the available color books (on the Color Books tab). Tip: Keep ambient light levels as low as practical. Too high an intensity tends to give renderings a washed-out appearance. Controlling Individual Lights The Lights area of the dialog box contains a list of lights that are already placed within the drawing, along with controls for modifying existing lights and creating new ones. Initially, the list is empty, because the model contains no lights. AutoCAD supports three different types of lights in addition to ambient light: Point Light Radiates light in all directions, and the intensity of the light diminishes over distance. A point light simulates the light from a light bulb. Distant Light Emits light that travels in parallel rays in a single direction and does not diminish over distance. A distant light is used to simulate sunlight, and AutoCAD includes a built-in solar light calculator (which you will learn about shortly) that lets you position a solar distant light source based on your latitude and longitude, time of day, and day of the year. Spotlight Emits a directional cone of light that diminishes over distance. Spotlights also mimic actual spotlights in that the light in the central portion of the cone is brighter than the light around the edges of the cone. You can adjust the angle that defines the central portion, or hotspot, and the rate at which the light diminishes, called the falloff. To add a new light source, select the type of light from the drop-down list and then click the New button. The dialog box displayed varies, depending on the type of light that you select. Note: When you modify an existing distant light, AutoCAD displays a Modify Distant Light dialog box, which is identical to the New Distant Light dialog box, but already contains the settings for the selected light. You can control both the placement of the distant solar light source, based on a particular date and time, and the location, based on latitude and longitude. These settings automatically control the Azimuth and Altitude settings. 6

7 Insert Class Title as per Title Page If you don t know the latitude and longitude, you can select the location of your model from a map or a list of major cities. The dialog box initially shows a map of North America, but you can display a different map by choosing the geographic area from the drop-down list located above the map. You can choose from North America, Canada, Europe, South America, Asia, Australia, the Asian subcontinent, or Africa. After you select the geographic area, you can specify the exact location by clicking on the map or by selecting a major city from the City list. If the Nearest Big City check box is selected when you click on the map, the location automatically jumps to the nearest city in the adjacent list. The Latitude and Longitude values are automatically filled in for the location that you select. Tip: You can add cities or locations by editing the SITENAME.TXT file in the Support folder. If you do not know the latitude and longitude for the location you are adding, you can use the Geographic Location dialog box to establish a rough estimate, by clicking the location of the city or the location that you need. The Latitude and Longitude fields are immediately updated. Make a note of these values and then use them when editing SITENAME.TXT. Adding Shadows Remember that one of the controls in the New Distant Light dialog box lets you turn shadows on and off. Computing shadows adds a considerable amount of time to the rendering calculations. For that reason, you must explicitly turn on shadows for each individual light that you add to the drawing. In addition, when you generate the rendering, you can still turn shadows on and off. When enabled, AutoCAD calculates shadows only for those lights that also have their shadow selection enabled. Note: AutoCAD calculates shadows only when using the Photo Real or Photo Raytrace rendering options. In addition to enabling shadows, you can control the type of calculation that is used to compute those shadows on a light-by-light basis. AutoCAD supports three different types of shadows. You can control the type of calculation on a light-by-light basis by clicking the Shadow Options button in the New or Modify Light dialog box for the selected light, which displays the Shadow Options dialog box. When the Shadow Volumes/Ray Traced Shadows check box is selected, AutoCAD generates volumetric shadows or raytraced shadows, depending on whether you render using the Photo Real or Photo Raytrace renderer, respectively. When this check box is not selected, AutoCAD uses shadow maps to create shadows for both renderers. When creating volumetric shadows (Photo Real renderer), AutoCAD computes the volume of space cast by the shadow of an object and generates a shadow based on this volume. Volumetric 7

8 Rendering in AutoCAD? Yes! shadows are hard edged, but their outlines are approximate. Volumetric shadows cast by transparent or translucent objects are affected by the color of the object. When creating raytraced shadows (Photo Raytrace renderer), shadows are generated by tracing the path of the beams of light from their light source. Raytraced shadows have hard edges and accurate outlines, and transmit color from transparent and translucent objects. When the Shadow Volumes/Ray Traced Shadows check box is not selected, AutoCAD uses shadow maps for both Photo Real and Photo Raytrace rendering. Shadow maps provide the only method of creating soft-edged shadows, but they don t show the color that is cast by transparent or translucent objects. You can control the size of the shadow map generated for each individual light by selecting the size of the shadow map from the drop-down list. The larger the value, the greater the accuracy of the shadow map. You can also control the softness of the shadow s edge by adjusting the number of pixels along the edge that are blended into the underlying image. Values of 1 to 10 are possible, but the best results are usually obtained with a setting between 2 and 4. With spotlights, the relationship between the shadow map size and falloff area determines the final resolution of the shadow. Note: Shadows greatly increase rendering time. Volumetric shadows tend to be faster than raytraced shadows in simple models. In more complex models, however, raytraced shadows are quicker to calculate. Although faster, shadow maps are also quite time-consuming to calculate, and AutoCAD must calculate each shadow map individually. You can improve rendering time when using shadow maps, however, by hand-selecting just those objects that you want to cast shadows. To do this, click the Shadow Bounding Objects button in the Shadow Options dialog box, and then select just those objects in the drawing. Working with Materials Attaching realistic materials to the objects in your model truly brings those objects to life. By attaching materials and adjusting the way that they appear on those objects, you make the flat surfaces appear to be made out of real brick and mortar. As with applying lights, attaching materials is an iterative process. You not only attach the materials, but you often must also adjust their scale and mapping. After each change, you will probably want to render the image. As the rendering times become longer, you ll see why AutoCAD lets you selectively render individual objects or small areas of the drawing prior to rendering the entire image. You attach and manage materials by using the Materials dialog box. The Materials list contains the materials already available in the current drawing. The default material for objects with no other material attached is *GLOBAL*. Before you can attach materials to objects in the drawing, you must either load predefined materials or create your own. AutoCAD comes with a materials library (RENDER.MLI), which is located in the Support directory. By default, the program uses this library file. You can also create and save your own materials library files and add custom materials to these files. To load predefined materials, click the Materials Library button to display the Materials Library dialog box. The Materials Library dialog box is split into two sections. The Current Drawing list on the left side contains the materials already loaded in the current drawing. The Current Library list on the right side contains the names of all the materials in the current library. To add one or more materials 8

9 Insert Class Title as per Title Page from the library to the current drawing, select them in the Current Library list and then click the Import button. Other controls in this dialog box let you save, remove, or delete materials from the various lists, save materials library files, or open different libraries. Note: You can also display the Materials Library dialog box using the MATLIB command. When the Materials Library dialog box is started in this way, you can add materials to the list of those available in the current drawing, but you can t attach those materials to objects in the drawing. You can attach materials only by using the Materials dialog box. The Preview area is particularly handy. Until you become more familiar with the many predefined materials, the only way you have of knowing what a particular material looks like is to preview it. This same Preview area occurs in all the other dialog boxes that deal with materials. To see what a material looks like, select it in either list and then click the Preview button. The material is mapped onto either a sphere or a cube, whichever you selected from the drop-down list. AutoCAD provides three different methods for attaching materials to objects in your drawing: By selecting the objects By attaching materials to objects based on their AutoCAD Color Index (ACI) number By attaching materials to objects based on the layer on which they are drawn The method that you choose depends primarily on how you created your drawing. Obviously, in more complex drawings, attaching materials based on ACI number or layer is easier than selecting objects individually. Tip: You can select more than one material at a time by pressing the CTRL key as you select the materials. Then, click Import to add the selected materials. You can also add consecutive groups of materials by holding down the SHIFT key while selecting the first and last material in the group. More About Attaching Materials If you attach materials on a per-object basis, you need to be aware of the type of object to which you attach the material. If the object is a block and that block is subsequently exploded, the material that was attached will no longer be attached to the individual objects. Materials that were attached to objects before being combined into a block, however, retain their respective materials within the block, and also retain them if the block is subsequently exploded. When you copy an object that has a material attached, the material is copied as well. Unfortunately, materials are not applied when objects are attached as external references. You must bind the xref to regain its material properties. In addition, if you insert a block that has 9

10 Rendering in AutoCAD? Yes! attached materials, you also need to import any custom materials from that drawing into the current drawing. Tip: You can use the SHOWMAT command to display the type of material attached to any object in an open drawing except objects in attached xrefs. The command also displays the method used to attach the material to that object. To start the command, type SHOWMAT and then press ENTER. AutoCAD prompts you to select an object. As soon as you select the object, AutoCAD displays the material name and attachment method. Adjusting Bitmaps AutoCAD s materials fall into two distinct categories: bitmaps and procedural materials. Materials such as SAND TEXTURE are based on bitmaps, scanned raster images of actual materials. In this case, AutoCAD uses a file called SAND.TGA. The size at which those materials appear in your drawing is determined by the size of the bitmap image. Procedural materials, such as granite, marble, and wood, are generated mathematically. You can adjust the bitmap, so that it is scaled more appropriately for your drawing, by selecting the material in the Materials dialog box and then clicking the Modify button. AutoCAD displays the Modify Standard Material dialog box for the selected materials. This dialog box provides controls that enable you to change the appearance of the material in many ways. The radio buttons in the Attributes area determine which aspect of the material is being changed. You can then adjust the values for the selected attribute by using the controls in the other areas of the dialog box. In the case of standard materials (those based on bitmaps), these attributes are as follows: Color/Pattern Determines the color, bitmap blend, bitmap name, and bitmap scaling Ambient Determines the shadow color of the material Reflection Adjusts the reflective color of the material and lets you specify a reflection bitmap Roughness Adjusts the roughness or shininess of the material 10

11 Insert Class Title as per Title Page Transparency Adjusts the transparency of the material and lets you specify an opacity bitmap and a reflection map Refraction Adjusts how refractive the material will be when rendering using the Photo Raytrace renderer Bump Map Lets you specify the name of a bitmap file to be used as a bumpmap; bumpmaps make a material appear to have more three-dimensional depth Note: When you modify the material, you change the parameters that affect the appearance of the material wherever it is attached in the drawing. You can also adjust bitmaps on an objectby-object basis. To revert back to the original material properties, you can reimport it by using the Materials Library dialog box. Mapping Materials onto Objects Sometimes, when you attach a material to an object, the material doesn t look right instead of simply being the wrong scale, it appears as a horizontal or vertical streak of color. Such strange appearances are generally caused by the material not being properly aligned or projected onto the object to which it is attached. The SETUV command lets you specify how materials are mapped onto objects. When you start the command, AutoCAD prompts you to select objects. As soon as you select the object whose material mapping you want to adjust, AutoCAD displays the Mapping dialog box. The buttons in the Projection area let you specify the type of projection used to map the material onto the object. After selecting the projection, you can click the Adjust Coordinates button to display the Adjust Coordinates dialog box for the particular type of projection you selected, and adjust the way the material is mapped onto the object. You can also acquire material mapping from any existing object or apply the mapping you establish within the dialog box to any other objects in the drawing. Planar Maps the material onto the object as though it were projected from a slide projector onto a flat plane. The material bitmap is scaled to fit the object, but it isn't distorted. You can select the reference plane, adjust the X and Y offset and rotation angle of the material, and adjust the bitmap placement. Cylindrical Maps the material onto a cylindrical object so that the bitmap's horizontal edges are wrapped around the object. The height of the material bitmap is scaled along the cylinder's axis. You can select the parallel axis around which the material is wrapped, adjust the X and Y offset and rotation angle of the material, and adjust the bitmap placement. Spherical Maps the material both horizontally and vertically. The left and right edges of the material bitmap are wrapped around the sphere. The top and bottom edges of the bitmap are compressed to points at the north and south poles of the sphere. You can select the parallel 11

12 Rendering in AutoCAD? Yes! axis around which the material is wrapped, adjust the X and Y offset and rotation angle of the material, and adjust the bitmap placement. Solid Applies materials based on three mapping coordinates U, V, and W enabling you to apply materials from any angle. You don't need to specify mapping coordinates for these materials. By changing the mapping coordinates for solids, however, you can skew the material pattern along any dimension of the solid. Tip: To delete mapping coordinates assigned to an object, use the AutoLISP version of the SETUV command, as follows: Command: (c:setuv "D" (ssget)) Select objects: (select the objects whose mapping you want to delete) Select objects: ENTER Adding Your Own Materials In addition to using the materials that come with AutoCAD, you can create your own materials. While creating your own standard materials requires that you obtain bitmap images of materials (either by photographing or scanning your own images or by obtaining images from a commercial library or some other source), creating your own procedural materials is relatively easy. Adding More Materials Selecting the appropriate materials is a bit of a trial-and-error process. For example, when you add glass materials to windows, AutoCAD provides several standard glass materials. Here is where adjustments to the Reflection and Refraction settings can really make a difference. Adding a Background Adding a realistic background is a wonderful and easy way to dress up a rendering. When you add a background, AutoCAD renders the model against the background. You add a background by using the Background dialog box. Note: You can also display the Background dialog box by clicking the Background button in the Render dialog box. You can add any one of four types of backgrounds. The four radio buttons across the top of the dialog box let you determine which of the background types to use: 12

13 Insert Class Title as per Title Page Solid Uses a single background color, specified in the Colors area of the dialog box. This is the default option, and, by default, AutoCAD uses its graphic window background color as the background color for the rendering. Gradient Uses a two- or three-color gradient. The controls in the Colors area enable you to define these gradient colors. Image Uses a bitmap file as the background. You specify the bitmap file in the Image area. You can also specify a second bitmap as an environment map. This map is used to create reflections when you use the Photo Raytrace renderer. Merge Uses the current AutoCAD image as the background. Adding Landscaping and People The real world is a pretty cluttered place. It s filled with trees and bushes, and if you ve ever tried to take a photograph of a building, you know that it s next to impossible not to include some people in the image. Rather than making the image look cluttered, however, landscaping makes it look more realistic, and including people in your rendering gives it a better sense of scale. You add landscaping and people by using the Landscape New dialog box. The left side of the dialog box contains a list of landscape objects contained in the current landscape library file. To add one of these objects to the drawing, select the object from this list and then click the Position button. When you click this button, the dialog box temporarily disappears and AutoCAD prompts you to choose the location of the base of the landscape object. You can specify the location of the object by pointing in the drawing (perhaps with the aid of an object snap) or by typing coordinates. Remember that the point you specify represents the base of the object. When you insert a landscape object, you need to pay particular attention to the settings in the Height and Geometry areas. In the Height area, use either the edit box or the slider bar to adjust the height of the object, measured in drawing units. The controls in the Geometry area determine the geometry and alignment of the landscape object: Single Face Maps the landscape object onto a single face. Single-face landscape objects render quickly, but may not look as realistic as those mapped onto crossing faces. Crossing Faces Maps the landscape object onto two faces, which cross at a 90-degree angle. Crossing-face landscape objects often look more realistic, but take longer to render. View Aligned Adjusts the faces onto which the landscape object is mapped so that one face is always aligned directly toward the camera. Landscape objects are created as ARX objects. They appear in the AutoCAD drawing as triangles and are treated like any other AutoCAD object. When you use the RENDER command, however, the objects appear as realistic-looking trees, bushes, and people. Since AutoCAD treats these special objects as it does any other drawing object, however, you can insert a single instance of a bush and then copy or array that bush to quickly add foliage. AutoCAD treats people the same as other landscape objects. 13

14 Rendering in AutoCAD? Yes! Note: AutoCAD limits the height value to 100. Since you need to create a tree taller than 8 feet, you need to scale this object after it s inserted. This limitation didn t exist prior to AutoCAD In Release 14, you could have specified the height as 300. Adding Landscape Objects AutoCAD comes with a landscape library (RENDER.LLI), which is located in the Support directory. By default, the program uses this library file. You can also create and save your own landscape libraries by using the Landscape Library dialog box. You can use the controls in this dialog box to modify existing landscape objects, create new ones, or delete objects from the landscape library file. You can also save and load custom landscape libraries. Landscape objects are created and modified by using the Landscape Library Edit dialog box. This dialog box enables you to define the object s default geometry. The other parameters define the name of the object and specify two files that are used to control the appearance of the object. The Image and Opacity Map files are both bitmap image files. The Image file contains a picture of the landscape object. The Opacity Map file is a similar file, but rather than being an actual image of the landscape object, this file is a black-and-white image called a mask. The mask defines the areas of the image that you can see through. The black portion of the image represents the transparent areas, and the white portion represents the opaque areas. Note: Don t despair if you make a mistake when you add a landscape object. You can always use the LSEDIT command to edit landscape objects that are already in the drawing. When you start this command, AutoCAD prompts you to select the landscape object that you want to edit. As soon as you select the object, AutoCAD displays the Landscape Edit dialog box, which is identical to the Landscape New dialog box. You can use the controls in the dialog box to modify the height, geometry, and position of the landscape object. 14

15 Insert Class Title as per Title Page Using Scenes Just as a single drawing can contain many named views, you can also define different scenes. In addition to saving the viewpoint, scenes also store a list of associated lights. This feature enables you to add additional lights to a drawing and use specific lights to render different scenes. The Render dialog box contains a list of scenes, and you can select the scene that you want to render. If you don t use scenes, you simply render the current view. If you save additional scenes, when you use the RENDER command to render the drawing, you can select the scene that you want to render. You create scenes by using the Scenes dialog box. This dialog box contains a list of all the scenes defined in the current drawing. The buttons in this dialog box enable you to define new scenes, modify existing ones, and delete any scenes that you no longer need. To create a new scene, click the New button to display the New Scene dialog box. This dialog box contains three controls. The Scene Name edit box is where you specify the name of the scene. The Views list on the left side of the dialog box contains a list of all the named views defined in the current drawing. The Lights list on the right side contains a list of all the lights already created in the current drawing. 15

16 Rendering in AutoCAD? Yes! The previous rendering used only the sun light source. If the drawing contained additional lights point lights inside the building to illuminate the interior at each floor, a point light to illuminate the area under the portico, spotlights used as down-lights to illuminate the side entrance, and two relatively bright spotlights to illuminate the front of the portico you could use the SCENE command to create scenes for the daytime and nighttime views. You can also create scenes that produce renderings from different viewpoints. Rendering to Other Destinations In addition to rendering directly to the current AutoCAD viewport, you can render to either of two other destinations: the Render Window or a file. The Render Window is actually a window created by AutoCAD s Render application, which, as you ve already learned, is a separate application that is loaded into memory whenever you use any of AutoCAD s rendering commands. Rendering to a file enables you to save the rendering to a file rather than simply display it on the screen. When you render to the Render Window, you can also subsequently save the image to a BMP file or print it to any configured Windows system printer. Rendering to the Render Window also has the advantage of enabling you to render an image to its own window, which in turn enables you to render several different views and see them all onscreen simultaneously, so that you can visually compare the differences. You can also copy the image to the Windows Clipboard and paste it into another program. When you render to a file, you can click the More Options button to display the File Output Configuration dialog box. You can then choose from any of five file types: BMP, PCX, PostScript, TGA, and TIFF. You can also specify the color depth (selecting anything from a monochrome image all the way up to 32-bit color) and resolution. This enables you to create renderings using much higher resolutions and greater color depth than that supported by your graphics card and monitor. Tip: If you plan to create photographic-quality prints of your renderings, you probably need to render to a file using a relatively high resolution, such as 2048x1566. To render to one of these destinations, select the destination from the drop-down list in the Render dialog box. Choose the other rendering options as you normally would. Then, click the Render button. If you selected the Render Window, AutoCAD automatically switches to the Render application window and, after completing its calculations, displays the rendering. If you render to a file, when you click the Render button, AutoCAD displays a File dialog box so that you can specify the name of the resulting file. 16

17 Insert Class Title as per Title Page Tip: You can use the SAVEIMG command to save a rendering from the current AutoCAD viewport to a BMP, TGA, or TIFF file, and use the REPLAY command to display any image saved in these formats in the current viewport. In addition to typing these commands on the command line, you can start them from the menu by choosing Tools>Display Image. 17