Read Microsoft Word - MV-4 Architectural Visualization with Revit Course Handout text version

Autodesk Revit Architecture 2011

Architectural Visualization with Revit 2011

Tod Stephens MV-4

Course Summary:

This course will show how to create architectural visualizations with Revit Architecture. It will show how to optimize the mental ray rendering engine and work with exposure control settings, material library parameters, and photometric lighting settings. The procedure for setting up solar study, sun path and walkthrough animations will also be discussed, as well as the options for exporting Revit geometry to 3ds max Design.

Instructor:

Tod Stephens has been working in the CAD and Visualization field for over fifteen years. He is currently a BIM Consultant with his own company, NexGenViz in Tampa, FL and an Adjunct Instructor with the BIM and Interior Design departments of the International Academy of Design in Tampa. Tod teaches and implements several Autodesk applications including AutoCAD, AutoCAD Architecture, Revit Architecture and 3ds Max. Tod is an Autodesk Certified Professional in AutoCAD, AutoCAD Architecture, Revit Architecture and 3ds Max Design. He is President of the Tampa Autodesk Animation (3ds max/Maya) User Group and the Architectural Coordinator for the Tampa Bay AutoCAD User Group. Tod obtained his Bachelor's degree in Electrical Engineering from Cleveland State University and a Master of Science degree in Education and Technology from Walden University. He has an interest in Green Building and Sustainable Design, is a LEED-GA, a member of the South Florida Chapter of the US Green Building Council and an Allied Member of the Tampa chapter of the American Institute of Architects.

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Introduction

The Revit model must be a complete building model to render properly. Light sources will only render properly if the building model is a closed space that has floors, walls, windows, doors and roofs. Ceilings are required if ceiling-mounted light fixtures are part of the interior lighting design of the building. Materials and textures should be applied to all objects (for example, paint on the walls, glass in the windows and doors, and flooring materials). You can render 3D views of the building model. The rendered view could be a camera view or the default {3D} view in the Project Browser.

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Materials and Textures

After creating a 3D view to render, you will need to specify render appearances and textures for materials, and apply materials to the model elements.

Materials define the following: 1. 2. 3. 4. 5. 6. The color that displays in a shaded (non-rendered) project view. The color and pattern that display on the surface of an element. The color and fill pattern that display when the element is cut. The render appearance that displays in a rendered image, and Realistic view. Information about the material's description, manufacturer, cost, and keynotes. Structural information about the material (for structural analysis).

A texture is the characteristic physical structure of a material or an object. It is distinguished by the size, shape, arrangement, and proportions of its parts. Sand has a grainy texture, while plastic has a smooth texture.

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A bump map is a gray scale image. The lighter areas are rendered as raised portions of the surface and darker areas are rendered as depressions. The bump, or displacement, cause by the map is sensitive to the direction of light sources. You can specify a texture or bump map for a material by using a photo, image or procedure map. Revit uses the image to define the surface to give it texture. If you want to make your own texture that can be repeated like a tile (a tileable texture), use tiles and define a map image. Adobe PhotoShop can be very useful for creating and modifying bump and texture maps.

Color Map

Bump Map

Use the Texture Editor tool to align the texture of the render appearance to the surface pattern of the material. When you render a 3D view, the rendered image displays the texture, positioned as specified using the Texture Editor tool.

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The properties of render appearances vary depending on the mental ray shaders used to render them. A shader is an algorithm that tells Revit how to calculate surface rendering. Each shader requires different information to render the material accurately. Revit shaders include properties for Ceramic, Concrete, Generic Material, Glass, Glazing, Masonry/CMU, Metal, Metallic Paint, Mirror, Paint, Plastic/Vinyl, Stone, Water and Wood.

Color maps (bitmap images) are composed of a fixed number of columns and rows of pixels, each with a specific color value. A procedural map is generated by a mathematical algorithm. The types of controls you find for a procedural map vary depending on the capabilities of the procedure.

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Procedural maps included in the Revit Material Library: 1. 2. 3. 4. 5. 6. 7. 8. Checker - Applies a two-color checkerboard pattern to the material. Gradient - Creates gradients using colors, and blends. Marble - Applies a stone and vein color pattern. Noise - Creates random displacement of a surface based on the interaction of two colors, texture maps or a combination. Speckle - Generates a speckled surface pattern. Tiles - Applies a brick or stacked tiling of colors or material mappings. Waves - Simulates water or wave effects. Wood - Creates the color and grain pattern of wood.

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Setting up Lighting

After applying materials and textures, you need to define lighting for the building model. If the rendered image will use artificial lights in a building interior space, add lighting fixtures to the building model. If the rendered image will use natural sun light, define sun and shadow settings.

Artificial Lights A lighting fixture is a Component that emits light from one or more light sources. A lighting fixture is defined by a Revit lighting fixture family. Revit provides several lighting fixture families for wall lights, ceiling lights, table lamps, floor lamps, exterior lighting, and other types of lighting fixtures. You can use the Family Editor to design your own lighting fixtures. You can also download additional lighting fixture families from the Autodesk Seek Content Library and Revit user community websites such as Revit City (www.revitcity.com). When you want to load a ceiling mounted lighting fixture family into a project, make sure you are in a Ceiling Plan view of the project and your model contains a Revit Ceiling. If you do not have a Ceiling or are in a Plan View of the project, the light fixture will not insert into your model (it needs a ceiling to anchor to). Floor and wall mounted lighting fixture families do not have this limitation.

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The Revit Imperial library contains many types of lighting fixtures. They can be loaded into a project view by clicking on Home > Build > Component > Place a Component, then Load Family and navigating to the Lighting Fixtures folder in the Revit Imperial library. Loadable lighting fixture families include: 1. Ceiling Light: Flat Round, Linear Box 2. Downlight: Recessed Can, Spot, Strip, Under Cabinet, Wall Washer 3. Emergency Wall Light 4. Floor Lamp: Arm Extension, Hemispheric, Standup, Torchiere 5. Pendant Light: Disk, Hemispheric, Linear ­ 1 Lamp, Linear ­ 2 Lamp 6. Sconce Light: Flat Round, Sphere, Uplight 7. Spotlight: Exterior 8. Studio Light 9. Table Lamp: Arm Extension, Hemispheric, Standard 10. Troffer Light: 2 x 2 Parabolic, 2 x 4 Parabolic 11. Uplight: Strip 12. Wall Lamp: Bracket 13. Exterior: Bollard, Street Light, Wall Pack

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There are several standard lamps (light bulbs) available for selection in Revit: 1. Halogen 2. Incandescent 3. Xenon 4. Quartz 5. Fluorescent: Warm White, Cool White, White, Daylight, Light White 6. Metal Halide 7. High and Low Pressure Sodium 8. High Pressure Mercury 9. Phosphor Mercury In Revit, photometrics are parameters for creating realistic lighting fixture families. Photometrics help to define the visible light that displays in a rendered image of a building model. The photometrics that are available for a particular lighting fixture depend on its light source definition. They include parameters such as Light Loss Factor, Initial Intensity, and Initial Color Control. When you specify that the light distribution of a light source is Photometric Web, you can specify an IES file. An IES file is a text file provided by a lighting manufacturer. It describes the intensity of a light source at points on a spherical grid. It also describes the geometry of how the light comes out of the lighting fixture (the photometric web). Revit uses the IES file to make a photometric web to represent the light source. In general, IES files result in more accurate lighting results in rendered images. For information about the IES file format, go to the Illuminating Engineering Society of North America website (www.iesna.org). IES files can be downloaded from manufacturer websites such as www.gelighting.com and www.erco.com.

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Entourage

Plants, people, and cars can be added to the building model by loading components from the Entourage folder in the Imperial Library. RPC Plants and RPC people are ArchVision's RPC (Rich Photorealistic Content) files and can be used for more realistic renderings. RPC content is pictures of actual people and objects from multiple angles that display using a technique called image-based rendering. You can purchase and download additional RPC content from the ArchVision website, http://www.archvision.com. If you purchase additional RPC content, you must use the ArchVision Content Manager (ACM), downloaded from the ArchVision website, to manage it. You use the ACM only to manage additional RPC content that you purchase from ArchVision (you do not need to use the ACM for the RPC content that is provided with Revit).

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Mental ray settings

Once you have added materials and lighting to your building model, you are ready to render the image. You can define mental ray render settings such as Quality Level, Exposure settings and setting the background to Sky or Image in the Rendering dialog.

Rendering an image can be a time-consuming step if the quality level is set to High or there are glossy or transparent materials on objects. When you are working on a rendering in Revit, you need to start at a lower level of quality then the final image will require. When you first start testing your rendering settings, start at a Draft quality setting so the image will render quickly. Then, gradually increase the level of quality of the image as your design progresses. Revit rendering quality settings: 1. 2. 3. 4. 5. Draft Low High Best Custom

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Advanced Render Settings There are many settings in the Rendering dialog that allow you to fine-tune the quality of the final rendered image. These settings include controls for image precision, reflection and transparency options, and indirect lighting and sky illumination settings. Using these advanced settings typically increases the quality of the rendered image, but also takes longer to calculate. Increasing the quality level of each advanced setting adds to render time, and can substantially increase render time when several of the settings are increased simultaneously. Some settings may only increase the rendering time by several minutes, others may add several hours (or even days) to the rendering time.

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Daylight Portals When you render an interior scene, Revit automatically calculates daylighting, which is the amount of natural light from the sun that shines through windows and glass and enters into the indoor space of a building. Revit automatically calculates the amount of sunlight that will enter an interior space based on the position of the sun in the Revit Project. Sometimes the amount of light entering an interior space does not result in a high quality ("pretty picture") render. You can enable Daylight Portals when you render your image in Revit to help improve the quality of this light entering the interior view. Daylight Portals direct the sunlight through the windows, door and curtain walls that contain glass and improve the amount and effect of the sunlight.

The only time you need to use daylight Portals is when your 3D view is inside the building and the Rendering dialog Lighting Scheme includes the Sun. The two interior view Lighting Schemes that include the sun are Interior: Sun only and Interior: Sun and Artificial. The default setting in the Rendering dialog is to have daylight portals turned off. Daylight Portals are very useful when your interior rendering shows sunlight reflecting off surfaces in an unnatural way, or the sunlight appears speckled or splotchy. As with all additional rendering quality settings, daylight portals require a large amount of computer calculations and it will take longer to render the image, particularly at high quality settings. You can activate the Daylight Portals through the Render Quality Settings dialog.

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Print and Image Size You can control print and image size of the rendered image by rendering only part of the 3D view (using a render region, a crop region, or a section box), zooming in or out of the view, changing the output print resolution (in DPI), or changing the view scale. You can add several different backgrounds to a rendered image in Revit. You can but a solid color behind the building, or a sky full of clouds, or a custom image. The custom image could be a digital photograph or digital artwork created in Adobe PhotoShop. For a rendering of the exterior of a building, the background is inserted behind the building during the rendering process. For a rendering of an interior view of a building, you will see the background image through any window and glass openings. When using daylighting, the natural light calculated to enter the building is affected by the background that is selected. If sky and clouds are used for the background, the amount of clouds will have a direct impact on the quality of the sunlight entering the building. Having clouds in the sky will typically result in more natural lighting from the sun in interior views that are rendered.

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Exposure Settings After rendering an image, you can adjust exposure settings to improve the image. Exposure control (or tone mapping) is just as important as the lighting and materials used. Exposure control helps to convert real-world luminance values (the intensity of light per unit area) into a realistic image. It mimics the response of the human eye to the intensity of light with regard to color, saturation, contrast, and glare. If you know the desired exposure settings, you can set them before rendering the image. When you select a lighting scheme (such as Interior: Sun Only), the software uses default exposure settings, calculated for the type of light in the view.

Use the following settings to adjust the exposure of a rendered image: 1. Exposure Value: Overall brightness of the rendered image. 2. Highlights: Light level for the brightest areas of the image. 3. Mid Tones: Light level for areas of the image whose brightness lies between the highlights and the shadows. 4. Shadows: Light levels for the darkest areas of the image. 5. White Point: Color temperature of the light sources that should display as white in the rendered image. This setting is similar to the White Balance setting on digital cameras. If the rendered image looks too orange, reduce the White Point value. If the rendered image looks too blue, increase the White Point value. The Sun has a White Point value of 6500. Incandescent lights typically have a White Point value of 2800. 6. Saturation: Intensity of colors in the rendered image.

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Saving the Rendered Image After you have fine-tuned the render settings and rendered a final image, you can save the rendered image as a Project View or can be exported to a file (BMP, JPG,TIF or PNG).

If the images are for the Web or online, use JPEG or BMP file types. These file types have a small file size, but the quality of the image is reduced. JPEG and BMP files may not be suitable for images with large blocks of color or simple shapes, because crisp lines will blur and colors can shift. For higher resolution and quality, use TIFF or PNG file types. TIFF format typically produces large file sizes, but there is no loss in quality. PNG offers the highest quality, and PNG files are typically smaller than TIFF files. TIFF and PNG files preserve layers, alpha transparency, and other special features when saved and opened in Photoshop. These file types provide support for an embedded alpha channel which represents various levels of transparency. Images with an embedded alpha channel retain their transparency information when opened in PhotoShop. Like a mask, the darkest areas of an alpha channel are most transparent, white areas are opaque, and shades of gray represent varying levels of transparency. This masking ability can be used to create transparent areas in an image. If you export a rendered image from Revit as a PNG file and open the file in Adobe Photoshop, the background sky and clouds may not display (the background becomes transparent) due to the alpha channel transparency. Adobe PhotoShop can be used to enhance rendered image files in the following ways: 1. Adjusting image brightness and contrast. 2. Adjusting image color and tone. 3. Matching, replacing and mixing colors. 4. Desaturating colors. 5. Adjusting image sharpness and blur. 6. Correcting image distortion and noise. 7. Adding and blending layers containing text or additional images.

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Rendering Considerations

To create a rendering of the exterior of a building in Revit, you would typically set up a Sun system for exterior lighting (unless the scene is a night scene with only artificial lighting). Sun settings specify the position of the sun for a sun path, solar study, or walkthrough animation, and for rendered images. You use the Sun Settings dialog to define the sun's position by date, time, and geographic location, or enter azimuth and altitude values to see shadows cast from a sun position that is independent of time and place. To create a rendering of an interior space of a building in Revit, you would typically set up artificial lighting for the room (such as recessed can fixtures or pendent fluorescent fixtures). You have to decide if you want the Sun settings to be active, or turn the Sun settings off. If the interior space does not have any windows or other wall openings to the outside, no Sun is required. Turning off the Sun can reduce rendering times. Effective ways to reduce the amount of time required to render an image: 1. Reduce the number of model elements that the rendering engine must consider. For example, if a rendered image will not show furniture that exists on the far side of an interior wall, hide the furniture in the view before rendering. By doing so, you reduce the number of elements that the rendering engine must consider during the rendering process. 2. Change the view's detail level to coarse or medium. By reducing the amount of detail in the 3D view, you reduce the number of polygon faces to render, and thus reduce render time. 3. Render only the part of the 3D view that you need to show in the image and omit areas that are not required. You can do this using a section box, a crop region, the camera clipping plane, or a render region. Render performance is significantly affected by lighting calculations. Render time is directly proportional to the number of lights in the scene. In general, mental ray requires more time to render more lights. Consider turning off lights that are not required for the rendered image. In general, an interior view takes longer to render than an exterior view. An exterior view with no natural light (that is, at nighttime) that shows many interior lights turned on takes a long time to render.

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More accurate lights require more render time. The Emit from Shape setting for a light source can impact render time. For example, point lights render faster than the other shapes. Line lights are slower. Rectangle and circle lights are slowest to render. Revit uses area light sources to produce more realistic images, but they result in area shadows that are expensive to compute. If you increase the quality of soft shadows, render time increases. These settings are found under the Soft Shadow options in the Render Quality Settings dialog. Indirect illumination simulates the interaction of light with the environment by bouncing light off surfaces, including surfaces that are not directly exposed to a light source. If you increase the precision of indirect illumination and the number of bounces, you can improve the smaller, subtle effects of lighting, and the amount of light in a scene. However, increasing the amount of indirect illumination also increases the time required to render the image. These settings are found under the Indirect Illumination options in the Render Quality Settings dialog. When you use section boxes to limit the geometry being rendered, you can significantly reduce the amount of time required to render an image. You can also use light groups to turn off lighting fixtures, thus reducing the number of lights that will impact the rendered image. Lights that are not within the view can still have a significant impact on the quality of the rendered image. Section boxes exclude lights that are clipped. The combined use of section boxes and light groups can greatly reduce the amount of time required to render an image. The image size or resolution of a rendered image has a predictable effect on render time. The Image Precision (Antialiasing) setting affects render time in a similar way. Higher values for image size, resolution, or precision require more time to generate the rendered image. If you double the image resolution (for example, from 75 dpi to 150 dpi) without changing other settings, render time can increase by 2 to 4 times. Depending on the complexity of the image being rendered, the increase in render time can vary from 1.9 to 3.9 times, with an average of 2.7 times the render time of the original 75-dpi image. If you double the resolution again (from the original 75 dpi to 150 dpi, then to 300 dpi), each jump in resolution increases render time by 2.7 times. Therefore, if you increase the resolution from 75 dpi to 300 dpi, the render time is typically increased 2.7 x 2.7 times, or about 7.3 times the original 75-dpi render time. If you increase the resolution from 75 dpi to 600 dpi, the render time is typically increased 2.7 x 2.7 x 2.7 times, or about 19.7 times the original 75-dpi render time.

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Animation

Revit supports the following types of animation: 1. Single Day Solar Study: A photorealistic image of a building model used to evaluate the impact of natural light and shadows on the buildings and site over the course of one day. 2. Multi-day Solar Study: A photorealistic image of a building model used to evaluate the impact of natural light and shadows on the buildings and site over the course of several days. 3. Walkthrough: An animation that simulates a person walking through a building model along a defined path. Solar studies help you visualize the impact of natural light and shadows on both the exterior and interior spaces of a building model. You create solar studies to see how shadows from terrain and surrounding buildings affect a site, or where natural light penetrates a building at specific times of the day and year. Using the Sun Path and Sun Settings dialog, either individually or together, you can create solar studies of your building model. When you display both the sun path and shadows, you can view the sun position as well as the resulting shadows.

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The following solar study animation modes are available: 1. Single Day: Produces an animation that shows the movement of shadows at the project location for a specified date, time range, and time interval. For example, you can track shadows at hourly intervals for a project in Tampa, FL, on May 22 from 8:00 AM to 5:00 PM, or from sunrise to sunset. 2. Multi-Day: Produces an animation that shows the movement of shadows at the project location for a specified date range, time (or time range), and time interval. For example, you can view shadow patterns at 1:00 PM every day from November 1 through November 30 for a project in Cleveland, Ohio. You can also produce a study for this project that shows shadow patterns at hourly intervals from 9:00 AM to 5:00 PM over the same range of days.

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Use the following workflow to create solar studies: 1. 2. 3. 4. 5. 6. 7. Specify the geographic location of the project. Create a 2D or 3D view that supports the display of shadows. Turn on the sun path and shadows. Create a Single Day or Multi-Day solar study. If you created a Single Day or Multi-Day solar study, view the resulting animation. Save the solar study results. Export the solar study results.

You can export solar studies to several different file formats. The export file types include AVI, JPEG, TIFF, BMP, and PNG. AVI files are standalone video files. All other export file types have a single-frame format, allowing you to save specified frames of an animation as separate image files. When you want to export to a single-frame format, first create a folder in which to save the files (especially if you are exporting several frames). The export process saves each of the specified frames as a separate image file. The individual frames can then be imported into video production software such as Adobe After Effects to render a video with sound, titles and movie special effects.

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Walkthrough Animation A walkthrough is a camera that follows a path that you define. The path comprises frames and key frames. A key frame is a modifiable frame where you can change the direction and position of the camera. The path shows red dots to indicate key frames. You can create a walkthrough in a plan view, 3D views, and elevation and section views. If you are in a plan view, you can vary the height of the camera by offsetting it from a selected level. Enter a height in the Offset text box and select a level from the From menu. This can give you the effect that the camera is going up a flight of stairs. To draw the walkthrough path, you place the cursor in a view, and click to place the first key frame. Move the cursor in the desired direction to draw the path. Click again to place another key frame. You can place key frames anywhere, but you cannot change their position during creation of the path. You can edit the key frames after you finish the path.

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To edit walkthrough frames, open the walkthrough view, click Modify > Cameras tab > Walkthrough panel > (Edit Walkthrough). On the Options Bar, click the Walkthrough frame edit button (300). The Walkthrough Frames dialog has 5 columns that show the frame properties: 1. The Key Frame column displays the total number of key frames in the walkthrough path. Click a key frame number to display where that key frame appears on the walkthrough path. A camera icon displays at the selected key frame. 2. The Frame column displays the frame at which the key frame displays. 3. The Accelerator column displays numerical controls for changing the speed of the walkthrough playback at a specific key frame. 4. The Speed column displays the speed at which the camera travels along the path at each key frame. 5. Elapsed Time displays the amount of time that has elapsed since the first key frame.

By default, there is a uniform speed at which the camera travels along the entire walkthrough path. You can change the speed by increasing or decreasing the total number of frames or by increasing or decreasing the number of frames per second. To change the accelerator value for key frames, clear the Uniform Speed check box, and enter a value for the desired key frame in the Accelerator column. Valid values for the Accelerator are between 0.1 and 10.

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Once you have finalized your corrections to the walkthrough path, you are ready to export the animation to a video file. To export a walkthrough go to "R" > Export > Images and Animations > Walkthrough. To export a solar study go to "R" > Export > Images and Animations > Solar Study.

The only video file format available for export is the AVI (Audio-Video Interleaved) file format (the Windows standard for movie files). When exporting an animation and saving as an AVI video file, it is best practice to use a Video Codec to compress the video into a reasonable file size. Codec is short for compressor/decompressor and a video codec is an algorithm for compressing and decompressing digital video data. One of the codecs used by Revit is Cinepak, which is a good choice if you need videos to play on a wide variety of computers (even older, slower machines) and need videos that will run smoothly in Windows Media Player. Revit produces its highest-quality output by rendering single-frame TIFF or PNG files, but you can still get good results rendering AVI files.

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