You have just spent a significant amount of time learning about Revit Structure, creating models, and documenting them. But once you have your regular work done, you should take some time to show it off. However simple you find modeling your buildings, it may be difficult to gain a high level of familiarity with the rendering process because you may so infrequently render your projects. But keep in mind that you can gain much by exploring and implementing the rendering features contained in Revit Structure.
The rendering engine in Revit Structure enables you to create visual imagery of your models. You can then leverage these images in everyday as well as specialized uses.
In this chapter, you will learn to:
Determine what and when to model
Assign materials to your model
Define the quality and style of your renderings
Export your models for other uses
When you begin to plan your models, undoubtedly you make sure you are covering all the basics. You will have grids, columns, floors, beams, walls, and so forth. You will then begin your documentation process, adding details and schedules as needed. Some will be generated live by the model, whereas others will be just lines and text placed alongside your model objects. This will continue during the entire sequence of construction drawing development. Soon you will have a nice—and probably bloated—model, ripe for using beyond normal drawings.
But will you be able to use the model for these extra purposes? If you modeled every piece of steel in a composite steel structure, not only would your model be huge and probably slow, but the level of detail in it might very well be beyond extended use. If you make a highly detailed model and it takes an hour to render it once, that probably will not be suitable for your rendering needs.
In the next section we will cover developing limits on what to model, along with methods to understand and control model bloating.
The normal process of modeling should be measured against several tiers. The first tier is your plan drawings. If you see something on plan and not in any other view, the need to model in 3D, to start with, is subjective. Sure, do it, if the object in question is easy to make and a primary component of Revit Structure. Then there are the items you see on plan and in sections or elevations. These too should probably be modeled if for no other reason than you don't want to create them twice (plan and detail). It also will help that the model is dynamic (all views will be automatically updated).
So what do you not model? For example, on a steel joist roof system, bracing angles are often required for the structure design. These items could be modeled and then shown on plan—but it is doubtful that you would have to model them since these small items would not normally be shown in a building section.
But let's imagine for a moment that your project has a healthy fee and you have the time to model every little thing. Not only will it be fun to create that virtual building, but you will get the added benefit of doing material takeoffs quickly. You can also use these components for the next project, where you may not have the luxury of time. You have no reason to not model every little thing. But you know there has to be repercussions for that!
"Speed kills" is an old adage that many relate to driving an automobile. Go too fast and you lose control. Well, excessive modeling is sort of the opposite; you will have no usability or speed and simply want to kill yourself waiting for the model to respond! Certainly this is a joke, but many times it has proven true. If you model too much, your model will become so slow that you can't work at any reasonable speed—and that is if you are lucky! Overly large models also can become unstable and crash with little warning.
Now what does this have to do with rendering? It's simple: the model you make will "make or break" your modeling efforts. If a primary goal of modeling in Revit Structure is to create a nice rendering view, you should keep that in mind while creating your model. However, if your project is small and simple, you probably cannot overmodel beyond the rendering capabilities. If your model is a convention center with tens of thousands of steel sticks, that may pose a problem.
As you have learned already, Revit Structure is a database-driven system. Every single thing in the model impacts its size. In Figure 14.1, we have a steel beam next to a concrete beam. Do you think these two are the same in the BIM world? In a way, yes, both are beams, but in every other way, no. The concrete beam has properties to help it be a concrete beam. Likewise, the steel beam has properties to help it be a steel beam. But due to the nature of this object type, there is a lot more information for a steel beam. Not only does it have connection symbols, but a steel beam has additional invisible data in this view: the stick line representation as well as the fine detail-level information, which would show the curved interior edges of the wide flange.
When you activate the rendering process, the surface of the shapes is what takes Revit Structure time to process. A concrete beam with six faces (four sides and two ends) will take less time to render than a wide-flange beam. A typical wide-flange beam has 12 faces, but depending on the meshing/rendering process, it can have 18 faces. To figure it out for yourself, cover your shape with "rectangles" and then count them. So it would be logical to think that a steel beam can have three times the face count of a concrete beam and then perhaps take three times as long to render. A project with 5,000 steel beams could have a face count of 90,000—just for the beams. It is not unrealistic to have a project with over a million faces!
The key thing to keep in mind is to render what you need and not just what you have. If you can use a simplified shape, do so; it will cut down on the face count. Perform a regular basic rendering of your model, and track the model file size to compare with how long it takes to render. There is nothing worse than trying to get a high-quality render made but not have the time to create it.
Model creep isn't a term to describe a mean or scary model. It simply explains a tendency to model beyond your needs, resulting in a bloated model. Imagine you have a team of people working on a project and everyone is actively contributing to the model. You should approach your virtual model just as the general contractor would. There would be regular meetings to discuss what is getting built today, what not to build at all, and what is still to be built. Your virtual construction should be no different, if for no other reason than to keep track of what goes into your model. You might be a frugal modeler, putting in only what needs to be put in. But your coworkers might not be so studious and go overboard. They're off modeling turndowns on slab-on-grades. They're modeling plates for steel beam-to-column connections, as shown in Figure 14.2. They're placing cold-formed steel stud members at 16″ on the center in interior walls. If these are things you need to model, then all is good. But if not, you and your team need to talk. Any valid additional items would have to be managed and/or filtered so that you can later turn them off for your renders if needed.
The crux of creep is that you need to watch and be aware of what goes into your models so that you can better prepare for when you need to create renders. Once you know what to look for, you can begin to do some work!
Materials are the make-or-break component of a successful rendering. The world is your oyster, in a sense. You can make your rendering look like a cartoon, make it look realistic, or make it anywhere in between. The funny thing is that materials are often a source of so much aggravation, not because of the difficulty in using them but rather because everyone has an opinion, and just like art, beauty is in the eye of the beholder. Whereas lighting controls what you see and how flat or realistic the rendering is, materials convey object type regardless of the lighting.
As you begin to create renderings on a regular basis, you should define whatever styles you will offer to your clients, and then allow your clients to pick from your portfolio of options and the style of rendering they want you to develop. You might have a single-color material (gray) that you use for all objects. This would convey, without question, that the rendering is a computer model. This technique is best in early stages when form and volume are most important.
Another method is to have materials of a single color representing the components on the structure—for example, a white/gray for concrete objects and a deep red for steel objects, representing primer paint. You can use a photograph of a concrete wall surface with form holes as well as stains. This would be well suited for close-up images where the detail of the surface is an added bonus for faking realism.
Materials in Revit Structure can be thought of in two distinct fashions: those that are faked and those that are made of something real. In the following section, we will cover synthetic and realistic materials.
The first form of material we'll refer to as synthetic. It does not exist in the real world and generally is just a color with various reflective properties, like paint. A synthetic material is usually the best option for large-scale renderings. One caveat: since a synthetic material itself has no patterning, you will have to rely on lighting and shadows to help define limits of objects. What you will often see is a loss of definition between a foreground object and a background object of the same color. As shown in Figure 14.3, graphically the difference between the concrete column in the foreground and the concrete wall in the background is hard to discern.
So when using synthetic materials—that is, materials with no patterns—it is important to use variation in the colors to aid in the visual differences. As shown in Figure 14.4, all your concrete object types should have slightly different colors so that they contrast against one another.
Most people would prefer to see some sort of pattern on the rendered objects. It could be a concrete with aggregate showing, a masonry wall with grout lines, or steel with some weathering. Anything you can apply to an object that mimics its real-world properties will add a level of realism to your renderings. Take a look at Figure 14.5; this is a real photograph of a concrete surface.
Figure 14.5. When applied to objects, a real-world material (image) will make those objects look realistic.
Exercise: It's All Material
Applying materials to your various objects is fairly easy. In this exercise, you will experience firsthand the steps required. As shown here, this model has a steel material applied but lacks style. This exercise will determine what material is applied to the steel objects and then change it accordingly.
Access
MATERIAL.RVTat the book's companion web page (www.sybex.com/go/masteringrevitstructure2010under Resources & Downloads, Part 5 Tutorial files. This is a small model with a few beams and a column.On the Ribbon choose the Manage tab, and then click the Materials button on the Project Settings panel to open the Materials dialog box.
Scroll down in the Materials dialog box and select Metal – Steel – ASTM A992. This is the material assigned to steel beam and column families in this model.
Once the material is active, select the Render Appearance tab at the top of the Materials dialog box. A quick scan of the panel will show that the style of the material is based on Aluminum Anodized Dark Bronze. This is the default in Revit Structure 2010 and probably the first thing you should change in your templates.
At the top of the panel, click the Replace button; then, using the Render Appearance Library, type steel in the Search box at the top. This will reduce the available materials to those with "steel" in their name.
Now locate and pick Stainless Steel Brushed, and then click OK to close. The Materials dialog box now shows Stainless Steel Brushed as the appearance. Next you need to change the shininess of the material.
Within the Metal Properties area is the Finish drop-down list. Change the setting from Brushed to Satin. Then click OK to close. Now this revised steel material has a more realistic render appearance, as shown here:
Once you have materials properly applied to your model objects, as shown in the final illustration of the preceding exercise, you will be ready at a moment's notice to create renderings. Material configuration and assignment to objects is one of the primary purposes of a template file. You can spend time doing this once and then leverage that time over and over for later projects. The key is to know how your future renderings should be set up. A great example is steel. It can come in many surface styles, from weathering steel (orange rust) to gray primer, and in many paint colors as well. A good protocol is to create a series of material recipes to recall when needed.
You may think that just duplicating Metal – Steel – ASTM A992 over and over for each style would be a good method, but there isn't a good way to change all steel objects from one steel material to another. The quick method is to change the primary material, Metal – Steel – ASTM A992, to whatever style you want for most of your objects. Then, if needed, you can create additional materials for atypical steel objects.
Once your objects are properly materialized, you can begin to create renderings. The following section explores the ease in which you can obtain great imagery from your Revit Structure models.
A first step in understanding how to render is to know what you can render. Not every view in Revit Structure can be used for this purpose. Only isometric and camera views can be rendered. But that doesn't mean you can't render "flat" views—there are methods to follow for those as well.
To find out if you have a rendering option on a given view, look at the View Control bar for the view. Along with the scale, detail level, and other controls is a tool to open the Rendering dialog box. As shown in Figure 14.6, the icon is a teapot. This is in deference to the original teapot model used by many to develop their skills in this artistic arena.
Before you begin to render, prepare your system for the best possible performance. The mental ray engine can use up to four computer processors for rendering computations, so whatever you can do to reduce other active applications will help. Shut down your mail client and anything else not required during the time you will be rendering.
In addition, in your model you should hide unnecessary objects in the view you will be rendering. These might be objects that are on the far side of the model but that appear in the wireframe view. If you can see objects in the wireframe view, they will be rendered and, if applicable, covered by object faces in front of them. So why bother to render them—just turn them off.
You can also gain some performance by adjusting your detail level from fine to medium or coarse. For example, steel beams have filleted corners at the web/flange interfaces. If your point of view is outside the building, this curve will be small and not visible. But the mental ray engine will see it and develop a rendered solution for it. Again, you can increase performance by reducing the detail level. Finally, you can just adjust the area to render by using a crop region or a section box or by assigning a render region. (We'll discuss render regions a little later in this chapter.)
Now that you have properly prepared your to-be-rendered view, you can click the Show Rendering Dialog button.
The Rendering dialog box might appear a bit foreign to you. It contains controls that are unlike anything else in Revit Structure. As shown in Figure 14.7, the dialog box has several panels of controls to enable you to create renderings to meet your needs.
At the very top of the dialog box is the Render button. Perhaps this should have been placed at the bottom, since you click this button only after you've made all your setting changes. Just to the right is a Region check box. Check it, and Revit Structure includes a rectangular region within your active display, with grips on all edges and corners, as shown in Figure 14.8. These grips allow you to adjust the area of the view that is to be rendered. You can alter the region even when the Render dialog box is open.
Once you have made your adjustments to the region, you return to the Rendering dialog box. If you turn off the Region check box and turn it on again, the region will reset to the view default.
Depending on your rendering needs, the quality of the output you require can vary easily using the Quality controls. The following section demonstrates the types of quality and how to achieve them.
By default, Revit Structure provides five levels of quality: Draft, Low, Medium, High, and Best. Most users will settle for using only two or three levels, depending on the quality and time to complete they can accept. For purposes of this discussion, we ran a series of renderings on three settings. A rendering at Draft (see Figure 14.9) level took 1 minute, 3 seconds, to complete. A Medium-level (see Figure 14.10) rendering took 7 minutes, 49 seconds, to complete. Then, a rendering made at the Best level (see Figure 14.11) took over 2 hours!
In all three of these, the resolution was no different (1026 × 664) and each had a 16 million color palette. The difference was the level of quality of the computations for the rendering itself. The better the quality, the fewer mistakes, known as artifacts, that were left in the image. As shown in Figures 14.9, 14.10, and 14.11, each subsequent shot improved pixilation and thereby had smoother color blends. The full images are available for your review on the book's accompanying web page; look in the Part 5 Tutorial folder.
In most cases you should use Draft to define your basic lighting and area of the image. That way, once you're ready, rendering at Medium will produce reasonable results for most digital uses such as a Microsoft PowerPoint slide. When you need to print an image, then (and only then) you would commit the time for a Best rendering level. Remember that the resolution isn't the issue—it is the quality of the output and how "clean" it looks.
If you review the color images, you will notice that at Draft level the grass is very spotty. But at Medium and Best you can detect little to no difference in the grass. This is because the grass is actually an image, or grass tiled onto the topography object. Also notice the jagged edges on the Draft image that don't exist on the other two.
If none of the default quality settings work for you, or you just want to delve deeper into controlling the quality, all you need to do is click the Edit option in the Setting drop-down list to open the Render Quality Settings dialog box shown in Figure 14.12.
The Render Quality Settings dialog box has several sections available for adjustment. Preset quality levels are included that provide you with a way to tell what is set for each type. For example, you can tell that at Draft level the Image Precision setting is at 1 (jagged edges), but if Medium is selected the Image Precision setting is at 4. So if you just need the speed of Draft but want fewer jagged edges, choose the Custom setting and then set Image Precision to 4. Then click OK to assign those settings and return to the Rendering dialog box.
Here are the various settings for Render Quality:
- Image Precision
Adjust this value to lower the number of jagged edges in the rendered view. Values range from 1 (very jagged) to 10 (least jagged).
- Maximum Number of Reflections
Increase this value if objects are not shown within reflections of a rendered view. The range is from 0 (none) to 100 (absolute most available).
- Maximum Number of Refractions
Adjust this value when objects don't appear through multiple planes of glass. Values range between 0 (opaque) to 100 (transparent).
- Blurred Refractions Precision
Adjust this value when object edges or surfaces in blurred reflections are spotty. Values range from 1 (spotty) to 11 (smoothest).
- Enable Soft Shadows
Choose this option to permit shadows to be soft using the Soft Shadow Precision control.
- Soft Shadow Precision
If available, this option allows shadows to be set from 0 (spotty) to 10 (smoothest).
- Compute Indirect and Sky Illumination
Choose this option to permit light from the sky and object-bounced light into your scene.
- Indirect Illumination Smoothness
Adjust this to provide more detail on objects that are in shadow and lit by indirect lights. Values range from 1 (least detail) to 10 (most detail).
- Indirect Illumination Bounces
Adjust this value to permit objects in shadow to be lit by indirect lights. It controls how many times a light ray can bounce from object to object. This can lighten objects totally in shadow so that they can be seen. Values range from 1 (single bounce for lights) to 100 (highest number of bounces), but in general more than three bounces is not perceptible.
- Daylight Portals for Windows, Doors, and Curtain Walls
These controls apply only for daylight within an interior view and provide a means to get light in through the opening.
There are many components to render quality—luckily you can bypass most of them on your way to getting output. In the next section we'll examine output, settings, lighting, and backgrounds.
Once you have specified your quality level, you then determine the output required. The Rendering dialog box offers two options: Screen and Printer.
Screen will assign a resolution based on the visible model view. If you have a maximized viewport, the resolution will be as high as it can be. If you cascade or tile your views, the resolution will change. The resolution is directly related to the visible portion of the screen. For this reason, it can be difficult to hit specific resolution aspect ratios.
The only other option, which frankly isn't much better, is Printer. It allows you to render to a specific dpi (dots per inch). Available options include 75, 150, 300, and 600 dpi. If you need a specific resolution, you will have to render larger than you need and crop with an image-editing application such as Adobe Photoshop. Using an image-editing application to resize the image will lower the quality since the image will be pixilated.
For very high image resolutions, you will need to render in another application altogether, such as Autodesk's 3ds Max. Programs like 3ds Max permit finite control on image resolution and also have better material and lighting controls than Revit Structure.
Lighting with Revit Structure is probably the one area where you will not need to adjust much. Structural projects are generally designed using columns rather than solid perimeter walls, so exterior lighting (the sun) typically can be used to generate the light needed for the rendering. In addition, most structural firms are quite busy with the normal building work and don't have time to delve into light placement. (An exception to this is a parking garage designer who is also responsible for garage light placement.)
As shown in Figure 14.13, Revit Structure provides a number of lighting schemes you can choose from. For a typical exterior daytime rendering, you choose Exterior: Sun Only. Selecting a Sun Only option disables the Artificial Lights control. Likewise, if you choose any of the Artificial Only options, the Sun control list will be disabled.
Interior schemes with sun have the added option of permitting sunlight to enter the scene via windows, doors, and curtain walls. This scheme just allows it; you would still need to use the Render Quality Settings dialog box to include the portal sunlight.
If you choose a sunlit scheme, you then have the ability to tune the sun location to whatever your needs are. As shown in Figure 14.14, you not only can point the sun at the model from a specific direction, but you can also choose to use a yearly position, such as a solstice or equinox. If none of the default Sun locations meet your needs, click the Edit/New option to display the Sun and Shadows Settings dialog box. As shown in Figure 14.15, this dialog box has Name and Settings areas. Depending on what you selected prior to clicking Edit/New, the Still, Single-Day, or Multi-Day tab will be active. If you just need a Still (single) position for the sun but want it coming from the lower left of your model, you can duplicate the Sunlight from Top Left option and modify it.
Once you've duplicated the option, rename it Sunlight from Lower Left; then adjust the Azimuth value to 225 (degrees) and deselect the Relative to View check box. Deselecting the Relative to View option will "pin" the location of the sun regardless of the point of view.
The background you choose in your Revit Structure images is an important issue: you must decide whether your goal is realism or clarity, print or digital presentation, or another personal preference. As shown in Figure 14.16, Revit Structure offers up to six styles to choose from: No Clouds, Very Few Clouds, Few Clouds, Cloudy, Very Cloudy, and Color.
The No Clouds style is simply a fading gradient from a horizon gray to a sky light blue. This is generally a great choice and allows a modest level of realism but without the distraction of visible clouds.
The other cloud styles all include increasing cloud volume overlaid on the gradient sky. The last option is Color. When you choose Color, the Haze slider control changes to a color swatch with access to a Define Color dialog box. In the Define Color dialog box you can set a simple solid color or define one using Red/Green/Blue or Pantone catalogs.
Your choice should reflect your intended use for the image. Here are some good guidelines:
- Print (on paper)
Use a solid white background so that the model pops off the page. Color printers are notoriously bad when it comes to fill quality. If you must have a background image, then try to use a gradient with few clouds rather than a solid color.
- Digital (on screen)
You set this depending on whether the display will be seen in a darkened room or a bright expo hall. For dark conditions, use a solid black background so that the whiteness isn't overbearing to the viewer. In well-lit rooms, choose a white background so that you have good contrast visually.
Obviously, when creating a render the end use could be just about anything. You would be wise to run renders with solid black, white, and gradients. And then for good measure, export the black background image as a PNG so that you save a version with a transparency layer. Later, using an image-editing program, you can place your building in a site photograph by using a masking and transparency layer, or you can even place it into a photograph with you in it (see Figure 14.17). The next section discusses the PNG image format.
As you can see, you can take your render to a whole other level of interest.
The last control for backgrounds is a foreground element. The Haze slider control permits you to put a level of fuzziness or fog into your render. This feature is most useful if you are designing a roadway structure, such as a large span bridge, or a major metropolitan high-rise structure.
Once you have a rendering made, you then must decide what to do with the fruit of your labor. This section exposes a few options that come into play once you have successfully rendered and are mostly satisfied with the results.
As you begin to render models, take some time to go into the real world and look around. Develop an eye for what lighting looks like, and see how the sun and its contrast affects what you see. Contrast gives your renderings depth. Sure, you can render a model and include every little detail. But that isn't how the real world works. In the real world, some things are clearly visible, while others are hidden in darkened areas. This is where Adjust Exposure comes into play.
As shown in Figure 14.18, there is a multitude of things you can tweak to improve your renderings. In general, you will want to darken a given setting rather than lighten it.
Using exposure doesn't require repeated renderings—just one. You simply open the Exposure Control dialog box before rendering, reset the default values, and then click OK to close. You then render your scene at the quality level you want. Once again, you open the Exposure Control dialog box and then modify the settings and click Apply. Your rendered image will update accordingly. Once you have the look you want, you can close the dialog box by clicking OK and then save/export as desired.
If you intend to use your renderings in your project sheets, you can click the Save to Project button to place the image in a project view, and then you can drag it onto a sheet view.
This is a great feature—you can update the image simply by saving changes to the project and using the same name again. Doing so will overwrite the image, and once you return to the sheet, the revised image will be there.
Once you have your rendering, you probably will want to save it to a file you can use later. Revit Structure provides a number of image file types for you use, but they are not all created equal. Some are best suited for viewing, others for print media, and some for use within other applications.
The choice comes when you click the Export button in the Rendering dialog box. A standard Windows file-access dialog box appears that lets you save the image. As you can see in Figure 14.19, the default filename matches the view name being exported. The Save Image dialog box also contains a Files of Type drop-down list. The following are the file format choices:
- Bitmap (*.bmp)
This is an industry-standard format developed by Microsoft. The format is well known, and nearly every image-processing application can use BMPs. The format does not have a patent, which ensures its widespread use. However, the format tends to be uncompressed and therefore the images will often be very large and usable only for post-processing applications.
- GIF (*.gif)
CompuServe developed this image standard for use within its network. Originally very popular because of their ability to contain animation, GIFs are now somewhat antiquated because of their color depth limitation of 256. GIF does still have its uses, since GIF files can contain transparent layers that can be used in post-processing to aid in masking between photographic and render image overlays.
- JPEG (*.jpg, *.jpeg)
JPEG is today's standard for creation of user-ready images. The format has multiple compression levels and color depth controls, and it is generally well suited for Internet web presentation and standard-sized print uses. Due to its aliasing (pixel stepping), the JPEG is not suited for animation compiling. However, JPEG images can often be reduced in size while retaining a quality appearance.
- Portable Network Graphics (*.png)
Developed as the replacement for GIF, this format offers increased color depth but no animation options. It also does not have a patent and so has been refined over the years into a great option. The color protocol is only RGB, but since it contains a transparency layer, the PNG can be used for masking easily.
- TIFF (*.tif)
TIFF format is the workhorse of the professional media, including computer book publishing! The file format tends to be very large and the images can be lossless if desired. These image types are not well suited for Internet use; since they are formatted in CMYK color, they are heavily used where color-offset printing is done. A TIFF is often the best choice for post-compiling animations based on sequential images.
So, which do you use? If you are creating a single image for the Web or small 4″ × 6″ prints, use a JPEG. If you are creating an animation and intend to compile it post-render, use TIFFs for the images. If you are creating a tiny icon, use a BMP. If you desire an image you can print at 24″ × 36″, again use a TIFF for the best quality, or if size is an issue, use a JPEG. Finally, if you need to use the image layered with something else in post-render, then choose PNG.
The final option to examine in the Rendering dialog box is the simplest. The Display portion contains a single button control. Prior to rendering an image, this button is disabled. Once you have successfully rendered the view, this button reads Show the Model. And it does just that. When you click it, Revit Structure will clear the rendering from the Display area and replace it with the previous view of the model. Want to see the rendering again? Simple—click the Show the Rendering button and it comes back. We recommend that you save the model before switching back and forth between showing the model and showing the rendering.
You can close the Rendering dialog box, switch to other views, and as long as the rendered view stays open, you can recall the last rendered view any time. Once the model or view is closed, the rendered view will be discarded. Use Save to Project or Export if you will need the rendered view later.
As you now know, there is a lot of variation and control over the final product of your renderings. Next up is an exercise where you will get the chance to experience the process firsthand.
Exercise: Rendering Your Model
Now that you have a complete picture of the rendering process, it is finally time to render! The model you will render is sized for speed and ease of use; yours will be much more interesting! There isn't a whole lot to successful renderings; just remember that beauty is in the eye of the beholder (see the following illustration).
Open
RENDER.RVTfrom the book's companion web page atwww.sybex.com/go/masteringrevitstructure2010".Using the Project Browser, open the 3D View ISOMETRIC.
At the bottom of the ISOMETRIC view, click the Show Rendering Dialog button (the teapot).
In the Rendering dialog box, change the Quality setting to Medium.
Click the Render button at the top to create the rendering.
Depending on the speed of your computer system, after a minute or so the ISOMETRIC view window will render. Odds are it won't look all that great. It will be washed out since no settings have been changed—yet.
With the Rendering dialog box still open, click Adjust Exposure.
Click the Reset to Default button at the top of the dialog box.
Change the Shadows value to 3 and then click Apply.
Click OK to close.
Instantly the image will darken, gain contrast in the shadows, and become more acceptable. Next we will adjust the materials.
Use the Manage tab on the Ribbon and click the Materials button.
In the Materials list panel, locate and select Concrete – Cast-in-Place Concrete.
Select the Render Appearance tab and then click the Replace button.
Using the browser window, find and select Concrete. Then click OK to apply and close.
Scroll the Materials list panel to find and click the Metal – Steel – ASTM 992 material. Click the Replace button.
In the Search box, type Paint Dark Red Matte and then click OK to accept and close. The preview will change to a wall corner.
Click OK to close the Materials dialog box.
You now have changed the material for concrete to a less-dense pattern. And now steel is a red primer color. It's time to adjust the sun and render again!
The Rendering dialog box should still be open; if not, click the teapot again.
In the Lighting area, click on the Sun list and choose Edit/New.
In the Sun and Shadows Settings dialog box, click Duplicate with the Sunlight from Top Right option selected.
Name the sun location Sunlight from Lower Left and click OK.
With Sunlight from Lower Left selected, change the Azimuth value to 225 and uncheck the Relative to View check box.
Click OK to apply and close.
In the Rendering dialog box, click the Background Style list and choose Color. You then get a color button; click it and assign a black color. Click OK to close. Consider saving your model now for real work conditions.
Change the Quality setting to High and then click Render. Now get some coffee or check out
www.augi.com. The rendering will take a few minutes.
You have a good-looking rendering with a nice level of contrast and obvious steel elements, and it's ready for a video presentation, as shown here (the book graphic has an intentional white background).
Revit Structure offers two view types to render by. One is the 3D view you just witnessed. The other is by using a camera. Next, you will use a camera and then render from the ground point of view and add some clouds.
Using the Project Browser, open the Level 1 plan view.
Using the View tab on the Ribbon, expand the 3D View button and choose Camera.
Note that the Options bar now contains controls for camera setting and placement. The default values are fine; start with a point on the plan view to the lower right of the building.
After you select a camera point, move the mouse and pick a target point in the middle of the building plan.
Once you set a target point, a new camera view will be generated and displayed for you, as shown here. Then you can use the grip controls to fine-tune your view. Adjust it so that the entire building, including footings, is shown within the crop box.
The Modify Camera tab becomes active, so you will need to click the View tab. Then locate and click the Visibility/Graphics button on the Graphics panel. In the Visibility/Graphic Overrides dialog box, select the Show Categories from All Disciplines check box. Then scroll down the Model Categories list for Topography and check it. Click OK to apply and close.
Change the Background Style setting to Sky: Very Cloudy.
Open the Adjust Exposure control, reset the values, and change the Shadows value to 3. Click OK to apply and close.
Change the Quality setting to High. When ready (and when you have the time) click the Render button and once again take a break while it generates. The following graphic shows the final rendering.
Now that you have finally rendered a view, you can sit back and enjoy the fruits of your labor, right? If you are lucky, maybe! Most likely you will have more modeling to do along with rendering new images. A great technique is to create some cameras within in your model and use them repeatedly to always have the latest version fully rendered, ready for review.
But single-frame renderings are not the only thing you can do with this technology. As the following sections show, there are some nontraditional uses for rendering your models.
Also included in Revit Structure is a means of creating single- and multiple-day Sun studies. In the Sun and Shadows Settings dialog box is a tab area for Single-Day and another for Multi-Day. In general, these configuration options are not a concern for the structural designer; their inclusion in the software is because Sun studies are a part of the core Revit program.
The steps to create a study are simple:
Activate the 3D perspective view.
Using the View Control bar, open the Model Graphics Style pop-up list and assign Shading or Shading with Edges.
Activate the View tab and within the Graphics panel, click the dialog box launch icon, the small arrow to the right of the panel name. This will open the Graphic Display Options dialog box. From this dialog box click the builder button to the right of the Sun Position drop-down list. This opens the Sun and Shadows Settings dialog box.
In the Sun and Shadows Settings dialog box, choose either the Single-Day or Multi-Day tab. Click the Duplicate button and name the new location the same as your model location.
With the new location highlighted, click the builder button for Place in the Settings area.
Using the Manage Place and Locations dialog box that appears, locate your city or assign specific Latitude/Longitude values. If required, turn on the Adjust Daylight Savings check box. Click OK to close.
Click OK to close the Sun and Shadows Settings dialog box.
Click OK to close the Graphic Display Options dialog box.
Using the View Control bar, click the Shadows On/Off control (to the right of Model Graphics Style), and turn Shadows On. Note that you can also access the Graphic Display options here with this View Control bar. After you turn on shadows, you'll find that if you click on this control again you'll be able to do a preview of your solar study. You start the preview using the tools on the Options bar.
To formally present your study, choose the Revit Structure Application menu (the big R icon) and choose Export
Using the Length/Format dialog box, adjust for desired frame length as well as image visual style and size. Click OK when ready. Keep in mind that while Rendered is an option, the final result will take as long as one rendering does multiplied by however many frames are defined.
Then on the Export Animated Solar Study dialog box, assign a name and location for the exported file(s). If you choose the AVI format, the Video Compression dialog box will allow you to assign compression and codec format.
That's it—you've created a Sun study. Frankly, we suspect that not many of you will use this feature of Revit Structure, but it is good to know anyway. Next we will move into how to create walkthroughs of your models.
Video File Exports
Revit Structure AVI files typically are very large. To combat this you can use either the Cinepak Codec by Radius or Microsoft Video 1 compression (see the following graphic). Most animation professionals compile videos after rendering the animation to a series of sequential images. Exporting your frames to individual TIFs or another uncompressed image file type and then compiling into an animation via something like Adobe Premier will not only give you better quality and access to many more video file types but also permit effects and other after-render changes such as resizing, watermarks, and soundtrack mixing.
An underused feature of Revit Structure is the Walkthrough command. Use this command to create a path that a camera will follow; the command then exports single frames or an animation of what the camera sees as it moves along the path. The technique is not hard to apply; the key is to remember that the tool is there to be used.
Open a plan view and then activate the View tab on the Ribbon. Locate the Create panel, and from within it expand the 3D View button and choose Walkthrough.
The Options bar then displays Walkthrough settings. In general, a default of 5′-6″ as a head height is appropriate. You can also change the level you want to use as the basis for the walkthrough.
Click points on the plan; each successive point will move the camera and begin to define a spline-like pathway for the camera, as you can see in Figure 14.20. Imagine yourself the director of a movie deciding where each key frame or camera location should be for your scene. Revit will interpret what to show between each camera location along the path.
When you complete the path, click Finish Walkthrough on the Walkthrough tab.
Once the path is created, it will appear on the plan in a semi-selected state. Now click in empty space, and it will vanish from the plan view. Just as with a camera, you must select a walkthrough for it to be visible on the plan. And just like any other view, it will be stored in the Project Browser. Select any 3D view or walkthrough view in the Project Browser, and right-click to access the Show Camera option.
Using the Project Browser, find and double-click on the walkthrough view. Then click the View Properties button on the Ribbon to change the settings.
In the Instance Properties dialog box, change Model Graphics Style to Shading w/Edges.
Turn off the Far Clip Active option, thus allowing for full-depth views, as shown in Figure 14.21.
Scroll farther down and click the Walkthrough Frames button.
In the Walkthrough Frames dialog box, shown in Figure 14.22, change the Total Frames count to 200. Click OK, and then click OK again to close the Instance Properties dialog box.
Next we'll create the walkthrough animation:
Using the Project Browser, locate your walkthrough and activate it. Depending on your view, you might not see anything at first.
Use the Revit Structure Application menu and choose Export
The Length/Format dialog box will appear, which allows secondary changes to your animation timing and style. Just click OK to accept the defaults.
The Export Walkthrough dialog box appears, where you can specify if you want to create sequential images for later compiling or accept the default AVI format. For most walkthroughs, a Revit Structure–generated AVI will be fine.
Another method to review a walkthrough is the in-model playback feature. Once you have a walkthrough in the active view, click on the crop window, and click the Edit Walkthrough button. The Ribbon will change to the Modify Cameras tab. As shown in Figure 14.23, you now have controls for playback such as Play and Next Frame as well as Option bar adjustments for specific key frame locations.
Playback performance will be largely based on your model and the graphics style assigned, such as wireframe or shaded with edges. The purpose of a walkthrough is to study the model for coordination needs; it typically isn't for high-quality presentation, as shown in Figure 14.24.
Figure 14.24. A single frame of the model shows the reduced level of quality along with index text to indicate where along the walkthrough you are.
As you now know, you can put just about any view of your model out into some sort of rendered view. You can create images from basic quality level and style all the way up to high resolution and full shadows. Once you have the tools on your computer belt, you should apply them every chance you get.
For example, try taking advantage of how you break up your models. If you are doing an addition to an existing building, create another set of materials and object types for the existing structure in a flat gray, along with the new structure in a different color. Then when you render, you can present a clear difference between the old and new structures.
Revit Structure comes with mental ray, which is a third-party rendering application that several Autodesk products use and is by far the best rendering solution provided within the software to date. However, as you get better at developing rendering scenes, you might want a bit more control over the finished product. Revit Structure is natively a modeler, a BIM solution, and a great documentation tool; it isn't a superior program for rendering images.
A number of awesome solutions are available for rendering images of your models, and many of those programs are created by Autodesk. Most notable is 3ds Max, a longtime program of professionals worldwide. With the introduction of the 2009 class of programs, a new version also became available: 3ds Max Design. This Revit Structure version shares the same core platform as 3ds Max. As time progresses it will be further tweaked for the Revit user and solve more and more deficiencies.
At this time the best methods for getting model data into an outside rendering application are via DWG and the newest format, FBX. Each provides the basic goal of exporting model geometry into the rendering program, but each delivers different benefits, as you'll see in a moment.
The AutoCAD drawing file format DWG is probably the most-used format. It carries with it all the 3D geometry and, depending on the rendering application, can read camera and light elements. When exporting, you have a few options, such as specifying the type of objects you want in the newly created DWG file. You can access the Export CAD Formats dialog box, shown in Figure 14.25, by clicking the Application menu button and choosing Export CAD Formats
If you choose Export as Polymesh from the Solids (3D Views Only) drop-down list, most of the model objects will be saved as blocks in the DWG. Each block (for example, W-Wide Flange-Column – W10X49_1-196959-3D View 1) is named rather intelligently, with the family name, type, unique ID, and the name of the view tacked on the end for good measure. Note that one of the odd things about this format is the block. Not all elements are bundled into blocks. Regardless, all model objects below the block level are polymesh. If you then explode the polymesh objects, you will be left with elements. This format will also provide centerline geometry for all structural objects. This can be helpful if you need to model something natively within the rendering application since you will have the wireframe to build upon. Export as Polymesh is best suited for going right into the rendering application. If you will not be editing the DWG, try Export as Polymesh first.
If you choose Export as ACIS Solids, all model objects except topography will be exported as a mix of blocks and ACIS solids. If you explode the blocks, the resulting object will be a solid. As with the polymesh option, you will also get a centerline for all structural objects. This ACIS object type is well suited for editing within AutoCAD since you can use many solid editing tools to further refine your model. If you need to work on the model prior to rendering, or if you're just going into AutoCAD, then use Export as ACIS Solids.
If you choose Export as AutoCAD Architecture and AutoCAD MEP Objects, you can further instruct Revit Structure try to make all model objects intelligent-type objects. They will contain object types that AutoCAD Architecture can understand and manipulate. Most of these objects can be exploded further. It may take a few explode executions to turn the AutoCAD Architecture objects into 3D face objects. So if the exported model is intended to be used with ADT/AutoCAD Architecture, then use Export as AutoCAD Architecture and AutoCAD MEP Objects. Also, you will need to keep an eye on any radial geometry; the function still has difficulties manipulating this data.
Why go to all this effort? Because choosing the proper method will help you when you begin your rendering work. Let's assume you will be going from Revit Structure straight into 3ds Max Design. The best choice is polymesh. It will be smallest file type and is already a mesh.
When you import your file into 3ds Max Design, you will be asked how to derive the imported model. By Layer is the best method only if you spent a lot of time organizing your model objects in the DWG file. However, if you are trying to be as time efficient as possible, then use the Entity, Blocks as Node Hierarchy method. The reason By Layer isn't a wise choice normally is that many objects within Revit Structure belong to the same class and therefore the same layer. For example, steel beams and concrete beams are both structural framing and would be on the same layer. But if you derive by entity instead, then you will end up with type name access once you're inside 3ds Max Design. The type name will be easy to locate and select, and you can then apply required materials.
FBX is another player in the import world. This somewhat new format by Autodesk is a first stab at linking the rendering efforts in Revit Structure and AutoCAD into 3ds Max. Not only will it bring in the model objects, but it will also import cameras, lights, and materials. As you may know, you can choose one of two default rendering engines in 3ds Max. One is mental ray (the same as in Revit Structure); the other is V-Ray. You must set the default rendering engine in Max to mental ray, or the imported FBX file will not import correctly.
As shown in Figure 14.26, you can find this export option within the Application menu under Export
The only case where using FBX may be worth the trouble is if you are trying to match the point of view of renders done in Revit Structure. The materials, lighting, and even cameras are generally better off made in 3ds Max, so the ability to bring them in along with the model can be of little benefit.
Most professional rendering work is done not in Revit Structure but in some other application. The following section discusses what is involved in rendering beyond Revit Structure.
As mentioned earlier, rendering in Revit Structure is a great final touch for your modeling effort. You get a lot of bang for little effort. But you might want a little more from your renderings than Revit Structure can provide.
For example, you can also render clouds but are limited to the cloud generation in the software. With outside rendering engines, you gain control on material placement, tiling, transparency, and many other settings that you don't have in Revit Structure. You can also render with radiosity in Revit Structure but only with mental ray; there are many high-quality renderers out there and some are very fast. Object and subobject animation are not possible with Revit Structure; objects themselves cannot move in an animation. So if you wanted to do a construction-sequence animation, you would have to use an outside rendering solution, period.
Covering in detail the methods and applications for these is beyond the scope of this book, but here are few comparisons to consider. In Figure 14.27 is a project rendered to a high level with Revit Structure using mental ray, whereas Figure 14.28 is rendered in Autodesk 3ds Max Design.
Most would agree that there is a noticeable improvement in visual quality in Figure 14.28. For some it would be hard to quantify. But the combination of greater contrasts, smoother materials, more realistic lighting, and translucent ground surfaces provide an additional touch that may warrant investment in non–Revit Structure applications.
- Determine what and when to model.
Once you get going in Revit Structure, the ease of creating models is both a blessing and a curse. If you model too little, you don't achieve the desired result. If you model too much, then you will have so much more than you need, your renderings will take an excessive amount of time.
- Master It
Before modeling, develop a scope of what and when to model. Conduct team meetings with all project modelers so that everyone involved has rendering in mind as they do their work. Limit the complexity of your renderings by using appropriate detail levels.
- Assign materials to your model.
Actually rendering in Revit Structure isn't hard—having something render worthy is the hard part. Materials make or break your renderings. You can make your model look real or like a real model.
- Master It
As you develop your families, assign materials so that you can render on demand later. Using the Materials dialog box, create materials for steel and concrete for when they are viewed at a distance. Adjust materials for rendering even if you won't be rendering now. This will reduce the time needed to prepare for when you are asked to produce images. For real photographic needs, use materials that have few repeating patterns so that no matter the point of view, the materials you use will maintain a level of smoothness.
- Define the quality and style of your renderings.
When you begin to render your model, you can be overwhelmed with all the settings at your disposal. You can define where the sun is, what time of day it is, what resolution to create, and how detailed your images should be.
- Master It
Take a look around in the real world. Get a sense of what structures look like when they are under construction. Things are often dark; you don't always have to light everything up. When you create renderings, save time and create high quality only at the very end. Use the Rendering system with Autodesk mental ray to define a sun, adjust exposure, control shadows, and create renderings. Then save your rendering to any number of image types.
- Export your models for other uses.
Exporting your model for outside use is a typical activity of the true professional. You don't use one kind of writing implement, so you should not use only one rendering application.
- Master It
Once you have a 3D view active, you can export it to a DWG or FBX file to use in an outside application. Use the FBX format if you have Revit Structure cameras you want to export as well. Use the DWG format with polymesh for direct import into 3ds Max Design. But if you have very large models, you might want to use ACIS solids since that allows 3ds Max to control the meshing directly.