![[System rollout interface]](vray_for_3ds_max_manual/system/system.png)
Here you can control various parameters of V-Ray's Binary Space
Partitioning (BSP) tree.
One of the basic operations that V-Ray must perform is
raycasting - determining if a given ray intersects any geometry in
the scene, and if so - identifying that geometry. The simplest way to
implement this would be to test the ray against every single render
primitive (triangle) in the scene. Obviously, in scenes with thousands or
millions of triangles this is going to be very slow. To speed this process,
V-Ray organizes the scene geometry into a special data structure, called a
binary space partitioning (BSP) tree.
The BSP tree is a hierarchical data structure, built by subdividing the
scene in two parts, then looking at each of those two parts and subdividing
them in turn, if necessary and so on. Those "parts" are called
nodes of the tree. At the top of the hierarchy is
the root node - which represents the bounding box
of the whole scene; at the bottom of the hierarchy are the
leaf nodes - they contain references to actual
triangles from the scene.
Max tree depth - the maximum depth of the
tree. Larger values will cause V-Ray to take more memory, but the rendering
will be faster - up to some critical point. Values beyond that critical
point (which is different for every scene) will start to slow things down.
Smaller values for this parameter will cause the BSP tree to take less
memory, but rendering will be slower.
Min leaf size - the minimum size of a leaf
node. Normally this is set to 0.0, which means that V-Ray will subdivide the
scene geometry regardless of the scene size. By setting this to a different
value, you can make V-Ray to quit subdividing, if the size of a node is
below a given value.
Face/level coef - controls the maximum
amount of triangles in a leaf node. If this value is lower, rendering will
be faster, but the BSP tree will take more memory - up to some critical
point (which is different for every scene). Values below that critical point
will make the rendering slower.
Default geometry - internally V-Ray
maintains four raycasting engines. All of them are built around the idea of
a BSP tree, but have different uses. The engines can be grouped into
raycasters for non-motion blurred and for motion blurred geometry, as well
as for static and dynamic geometry. This parameter determines the type of
geometry for standard 3ds Max mesh objects. Note that some objects
(displacement-mapped objects, VRayProxy and
VRayFur
objects, for example) always generate dynamic geometry, regardless of this
setting.
Static - all geometry is precompiled into
an acceleration structure at the beginning of the rendering and remains
there until the end of the frame. The static raycasters are not limited
in any way and will consume as much memory as necessary.
Dynamic - geometry is loaded and unloaded
on the fly depending on which part of the scene is being rendered. The
total memory taken up by the dynamic raycasters can be controlled by the
Dynamic memory limit parameter.
Auto - some objects are compiled as static
geometry, while others as dynamic. V-Ray makes the decision on which
type to use based on the face count for an object and the number of its
instances in the scene.
Dynamic memory limit - the total RAM limit
for the dynamic raycasters. Note that the memory pool is shared between the
different rendering threads. Therefore, if geometry needs to be unloaded and
loaded too often, the threads must wait for each other and the rendering
performance will suffer.
Here you can control various parameters of V-Ray's rendering regions
(buckets). The bucket is an essential part of the distributed rendering
system of V-Ray. A bucket is a rectangular part of the currently rendered
frame that is rendered independently from other buckets. Buckets can be sent
to idle LAN machines for processing and/or can be distributed between
several CPUs. Because a bucket can be processed only by a single processor
the division of the frame in too small a number of buckets can prevent the
optimal utilization of computational resources (some CPUs stay idle all the
time). However the division of the frame in too many buckets can slow down
the rendering because there is a some time overhead related with each bucket
(bucket setup, LAN transfer, etc).
X - determines the maximum region width in
pixels (Region W/H is selected) or the number of
regions in the horizontal direction (when Region
Count is selected)
Y - determines the maximum region height
in pixels (Region W/H is selected) or the number
of regions in the vertical direction (when Region
Count is selected)
Region sequence - determines the order in
which the regions are rendered. Note that the default
Triangulation sequence is best if you use a lof of dynamic geometry
(displacement-mapped objects, VRayProxy or
VRayFur
objects), since it walks through the image in a very consistent manner so
that geometry that was generated for previous buckets can be used for the
next buckets. The other sequences tend to jump from one end of the image to
another which is not good with dynamic geometry.
Reverse sequence - reverses the region
sequence order.
Previous render - this parameter
determines what should be done with the previous image in the virtual frame
buffer when rendering starts. Note that this parameter has no effect on the
final result of the rendering; it is implemented simply as a convenient way
to distinguish between parts from the current frame being rendered, and part
left over from the previous rendering. The possible values are:
Unchanged - no changes will be made - the
virtual frame buffer remains the same;
Cross - every second pixel of the image
will be set to black;
Fields - every other line of the image
will be set to black;
Darken - the colors in the image will be
darkened.
Blue - the previous image is tinted in
blue.
Distributed rendering is the process of
computing a single image over several different machines. Note that this is
different from distributing the frame over several CPU's in a single
machine, which is called multithreading. V-Ray
supports multithreading, as well as distributed rendering.
Before you can use the distributed rendering option, you must determine
the machines that will take part in the computations. Both 3ds Max and V-Ray
need to be properly installed on those machines, although they don't need to
be authorized. You must make sure that the V-Ray spawner application is
running on those machines - either as a service, or as a stand-alone
application. Refer to the
Installation section for more details on configuring and running the
V-Ray spawner.
For additional information on distributed rendering, please refer to the
dedicated
Distributed rendering section.
Distributed rendering - this checkbox
specifies whether V-Ray will use distributed rendering.
Settings... - this button opens the V-Ray
distributed rendering settings dialog. See the
Distributed rendering section for more information.
The frame stamp is a convenient way to put some short text over the
rendered images. It can be useful in many ways - for example, in network
rendering, to quickly determine which frames were rendered by which machine.
The frame stamp is one line of text, which appears at the bottom of the
image.
Checkbox - turns the frame stamp on and
off.
Edit box - here you enter the text you
wish to appear in the images. You can also use some special keywords, all of
which begin with the percent symbol (%). The keywords are replaced by V-Ray
with the corresponding value:
Each message can fall into one of four categories, which are colored in a
different way in the messages window. Those categories are errors (colored
in red), warnings (colored in green), informative messages (colored in
white) and debug messages (colored in black).
![[V-Ray messages window]](vray_for_3ds_max_manual/system/messages.png)
These
parameters control the V-Ray messages window. During rendering, V-Ray writes
various information in the file C:\VRayLog.txt. The messages window shows
some of that information so that you can view it without the need to
manually open that file.
