Materials, Lighting, and Rendering

BIM for Architecture, Engineering, and Construction Curriculum


Assigning Materials to Model Elements

If you cannot find material settings in an element\u2019s type or instance properties, how can you assign materials to the object?

Changing an element's type or instance properties are high-level ways to edit materials assigned to the object. If these options are not available, the object style for the category that the element belongs to can be changed. For example, if a door is displayed as gray and material options are not available in its type or instance properties, you can change the object styles for the Door category in order to set a default material for all door components.

What are the advantages and disadvantages of assigning materials as type properties versus instance properties?

Instance properties allow for an easier way to create variability between multiple instances of the same component. If we have multiple objects that we would like to be different materials, instance properties allow us to change each one individually. However, if we want to change the material of many instances at the same time (like a large set of chairs), assigning materials as a type property is much easier.

If you want to define a new material for some elements in you model, is it better to change an existing material or to duplicate one and change the settings of the new material?

It is typically better to duplicate a similar material when creating a new one. This prevents you from deleting a useful material or accidentally changing a material that is being used elsewhere in the project.

Changing Material Display and Render Appearance

If you want to change the render appearance of some of the elements in your model, is it better to modify an existing material\u2019s settings or to create a new material and assign it to those elements?

If you are sure that you want to change the render appearance of every element using a specific material, then it is generally okay to modify the render appearance of that existing material. Otherwise, create a new material for each element that needs to be altered.

When creating new render appearances from photographs or scanned images of materials, what types of images work best?

Pictures and images with repeated patterns and limited distortions caused by a poor camera angle work best for creating new render appearances.

 Creating Exterior Rendered Views

How is the time required to render an image affected by the quality setting and output resolution?

Changing to a higher-quality rendering setting or raising the output resolution increases the time required to render a view.

How are the shadows cast affected by the location specified? By the date and time?

Any variable that affects the sun\u2019s location will have an effect on the shadows that are being displayed. If the sun is high in the sky, due to geographical location or an afternoon time setting, the shadows will be short and close to the structure. If the sun is low in the sky, the shadows will be very long.

If a completed rendering appears dark, is it better to rerun the rendering with different lighting settings or adjust the exposure of the existing image?

The fastest way to fix the darkness of an image is to adjust the exposure settings, so this method should be attempted first. If this does not produce the desired effect, the view can be rerendered using different lighting and sun settings. To save time, test render a portion of the image using the region box to see the effect of the setting changes.

Creating Interior and Nighttime Rendered Views

Why do renderings that include artificial light sources take so much longer to produce?

The rendering engine must consider and calculate the effects of the light being cast by each light source. Exterior rendering typically consider a single light source\u2014the sun. Interior renderings often include many light sources to illuminate the view, so the calculations and time required are multiplied many times.

How would you set up the lighting scheme for a later afternoon view to include the effect of sunlighting through the curtain wall as well some artificial lights?

By using the scheme Interior: Sun and Artificial, both the sun and artificial lights will be considered in the rendering. This also makes the Artificial Lights dialog box available.

What are the advantages of placing light fixtures in light groups? Are there any disadvantages?

There are typically no disadvantages to placing light fixtures in groups. Lights that have been grouped can be turned on, turned off, or dimmed simultaneously or controlled individually if desired.