Autodesk 24000-000000-9860 - Revit Architecture - PC, User Manual

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How Reflection Types Affect Render Performance
The render appearance of a material specifies its reflectivity. Revit Architecture can render matte reflections
quickly. However, any material characteristic that causes visual distortions (such as blurred reflections or
transparencies) requires more work to render, and so requires more render time.
Shiny and mirrored reflections are slightly more difficult to render than matte reflections. A fritted surface
is more difficult to render than a smooth, glossy surface. Water is more difficult to render than glass. Metal
with a patina or a hammered surface is more difficult to render than polished metal.
Blurred reflections are the most difficult to calculate. However, you can control the quality of blurred
reflections to reduce the impact on render performance. (Use the Reflections and Transparency options. See
Render Quality Settings on page 1163.)
How Refractions and Reflections Affect Render Performance
Refractive materials, like glass, usually involve reflections as well. As a result, these materials are more
expensive (in time and resources) to render than others. Also, the average pane of glass has 2 layers or sides,
requiring multiple layers of refraction. When rendering an image, all of the layers must be calculated so you
can see through the glass. For example, you need at least 6 refractions to see through 3 panes of solid glass.
When rendering an image, you can specify the number of bounces off reflective surfaces (Maximum Number
of Reflections), and the number of panes of glass for refractions (Maximum Number of Refractions). Higher
settings generally result in longer render times. Blurry refractions increase render time further. (In the Render
Quality Settings dialog, use the Reflections and Transparency options. See
Render Quality Settings on page
1163.)
Render Performance and Image Size/Quality
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. (See
Render Quality Settings on page 1163.) Higher
values for image size, resolution, or precision require more time to generate the rendered image.
Effect of Increasing Image Resolution
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.
Checking the Image Size
When defining the view area to render, check that the image size is appropriate and reasonable. If you specify
a very large image size, the render speed may be very slow.
■ Crop region : When using a crop region to define the view area to render, you can specify the height and
width of the crop region. (See Resizing Crop Regions Explicitly on page 166.) The crop region size defines
the paper size of the rendered image.
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