User manual

© Next Limit Technologies 2010
Maxwell Render 2.5 User Manual
Chapter 10. Maxwell Materials | 79
An example of how surface detail is affected by increasing gain for the same texture can
be found below:
Height: 25cm
Offset: 0
Gain: 2.5
Height: 25cm
Offset: 0
Gain: 12
Height: 25cm
Offset: 0
Gain: 32
F.01 Displacement Test
This example shows that going beyond a gain of 32 (in this particular case) would not
add more detail (while it would increase the render time). So it is important to avoid
unnecessarily excessive Gain values.
Adaptive
The adaptive option locks the gain value to the given texture detail (at half pixel accuracy),
which has the advantage of always creating the most detailed displacement that a given
texture can provide. The user does not have to guess what the maximum gain value
should be for that texture, or worry about exceeding it (which would increase render
times but would not necessarily increase image detail, see example above). The adaptive
mode should be used with care, because using a very large-resolution texture to represent
some simple detail will result in unnecessarily long render times. The larger your texture,
the longer the render times with Adaptive mode on because it will always render the
maximum amount of detail for that particular texture. Adaptive mode should be used
mainly to “test” your displacement textures rst to see how much detail can be obtained
from a given texture size. Then you can switch Adaptive off and manually raise the gain
value until a level of detail close to Adaptive mode is reached, but without increasing the
render time.
Smoothing
Similar to the object’s smoothing angle setting, this parameter controls whether the
displaced surface should render smoothly (continuous shading) or render faceted. It is
generally suggested you leave this setting to “on”, unless you aim to render very sharp,
detailed displacements. Please note that the objects smoothing angle will still override the
smoothing used for the object’s base mesh faces, so if the object’s smoothing angle is set
to Flat (rendering the object faceted), and the smoothing parameter is set to “on” in the
displacement parameters, a smooth displacement surface will be rendered over a faceted
base mesh surface.
u Tips to reduce the impact on render times:
Render times can vary greatly. These three factors play an important role in render
times:
• The base mesh vs. gain value (see below for details).
• The height of displacement (higher displacements will increase render times).
• How many displaced surfaces and objects the rendered image contains. For
example, a common usage of displacement may be for a brick wall seen from far
away, taking up 30-40% of the rendered image. In this case, low height and gain
values can be used, and the impact on render times will be minimal. On the other
hand, a close-up render of a displacement object taking up the whole image,
using high gain values, will need more time to render clean.
Base Mesh vs. Gain
The more polygons you have in your base mesh, the less gain you will need to render
the same amount of displacement detail. Displacements with less gain will always render
faster. For example, if you are planning to render displacement over a plane, model your
initial plane using more than 2 triangles. A typical 4 x 4 subdivision will speed it up
remarkably.