Updated 25th October 2004
The easiest and best way to reduce render time
is to lower the Image Quality setting. Reducing
image quality by 20 or 30 roughly halves render
time. To choose the quality setting, test the image
using its target display device or printer.
Do not choose Image Quality for an image that will
be printed by looking at the rendered image on the
computer screen. This leads to a lot of wasted rendering
time. A computer screen is typically between 70
and 100 dpi (dots per inch). Printing is typically
300 dpi or greater. This means that the pixels on
a computer screen are large compared to the ink
dots in printing (3 to 4 times wider, 9 to 16 times
greater area). Additionally the computer screen
will not show the effect of the ink dots bleeding
into the paper. The result is that any noise in
the image is much more apparent on the computer
screen than it is when printed.
If you are rendering an image to be printed then
an image quality of between 40 and 80 will usually
be sufficient. For video an image quality of between
50 and 100 will usually be sufficient. For images
that will be viewed on a computer screen an image
quality of 70 to 150 is appropriate.
Changing other render settings may also help. Reducing
ray depth can have a big impact but be very careful
not to make it too small. Increasing the detail
value can have an effect, though it does tend to
be much less.
If you are using the RP SSI material, follow the
advice in the release notes. Only use the SSI material
on surfaces where you really need to. Consider using
post-processing to reduce noise, just as you might
with a digital photograph.
Revising the lighting can also have a big impact
on render times:
Eliminate non-essential lights where possible.
For lights that only illuminate part of the scene,
switch on the Use option under Far Attenuation
and set the Far Attenuation range. This tells
the renderer the bounds of the scene that the
light can affect, so the light does not need to
be traced outside these bounds.
Large area lights are expensive to render, so
use them judiciously.
Use Chalk Preview to try out the lighting. If
the result is too white, the color render is probably
over lit. Consider re-lighting the scene, especially
if it was originally lit using a different renderer.
Switching on Analytical Light Sampling makes
renders take longer, but greatly improves the
results of area lights.
There is further advice on reducing render times
on page 11-3 of the PURE user manual and page 13-3
of the RenderDrive user manual.
New 12th March 2004
Yes, HDRI is supported. Support was added in RenderDrive
and PURE software version 3.1, RenderPipe MAX version
2.8 and RenderPipe for Maya version 1.6.
There are full details on HDRI support in the release
notes and user manuals, which can be downloaded
from the documentation page.
Both RenderPipe MAX and RenderPipe for Maya support
the use of floating point tif files. In 3ds max
6 you can also use HDR format files.
In RenderPipe for Maya there is a new type of light,
the RP HDR Skylight, which gives HDRI style illumination
from a half dome around the scene. The same light
is available in RenderPipe MAX through the RP RenderMan
Light.
New 25th October 2004
Analytical Light Sampling is an improved method
of rendering area lights. It usually produces much
less noisy results than the usual method of rendering
area lights. Its downside is that it does take longer
to render, but this is often balanced by the fact
that it is possible to use a much lower Image Quality
setting.
Analytical Light Sampling looks at the size of
the area and analyses how much it is lighting a
surface in order to decide how many light samples
to take.
All the RenderPipe interfaces have an Analytical
Light Sampling switch, which defaults to be off.
We recommend you switch off Analytical Light Sampling
when setting up scenes and switch it on for the
final render. When it is switched on be especially
careful not to choose an image quality setting that
is high - a setting of 50 will in many cases be
ample.
Many people make the mistake of choosing their
image quality setting based on what they see on
screen. The problem with this is that pixels on
screen are much larger and more precise than pixels
in a printed image. In a printed image the pixels
are much smaller and slightly bleed into each other.
Always choose your image quality based on tests
with your target media, otherwise you will end up
wasting rendering time rendering using an unnecessarily
high image quality setting.
Note that Analytical Light Sampling does not affect
the rendering of any other type of light, nor of
motion blur or depth of field. In particular it
makes no difference to the rendering of the RP HDR
Skylight.
See the following question and answer.
In RenderPipe MAX a lens effect can be applied
to an image through the RenderPipe cameras. In RenderPipe
for Maya, a lens effect is applied to an image by
adding a lensFX node.
Lens effects are applied as post process to the
image (or as a post process to each part of the
image). There is a very high memory requirement
for calculating lens effects, so there are limits
on the resolution of image lens effects can be applied
to. The exact limits are dependent on the scene.
RenderDrive: the limit is typically around 2500
x 2500. If there is not sufficient memory the render
will fail with a message like 'Render died' or 'Caught
segmentation fault'.
PURE: the limit is much more variable as it depends
on the memory in your workstation and what else
is running. The error message when there is not
sufficient memory typically starts 'Cannot mmap
file'.
To avoid this problem, switch off the lens effect.
If you are using PURE you can also try adding more
memory or closing other applications.
You can confirm this is the likely problem by looking
at the log file:
PURE: To look at the PURE log file right mouse
click on the PURE task bar icon and choose diagnostics.
If the problem is due to there not being enough
memory to calculate the lens effect, then the 'Cannot
mmap file...' message will be immediately after
a 'Processing rendition' message.
RenderDrive: You need to enable log messages before
rendering, see the answer to 'RenderDrive
log file empty - switching on logging of warnings'
below. If the problem is due to there not being
enough memory to calculate the lens effect, then
the render will have ended just after a message
saying 'Processing rendition'.
(Updated 30th May 2003)
Support for rendering a single frame using multiple
PURE cards or RenderDrives was added in version
1.4 of the PURE software and version 2.9 of the
RenderDrive software. When rendering a single frame
simply select the rendering devices you wish to
use in the render panel in 3dsmax / VIZ or Render
Globals in Maya.
If you are using version 1.3 (or earlier) of the
PURE software or version 2.8 (or earlier) of the
RenderDrive software it is not possible to render
a single frame straight from RenderPipe using more
than one PURE card or RenderDrive. If you are using
3dsmax 5 or VIZ 4 then you can use the 'Network
Render Region' option / MAX Script in combination
with the network renderer to render a frame using
multiple rendering devices.
(Updated 30th June 03)
In the initial release of RenderPipe RIB, frame
splitting within RenderPipe RIB is not functional.
This question will be updated once frame splitting
within RenderPipe RIB is supported.
If you would like to use frame splitting with RenderPipe
RIB, please contact ART VPS's Customer Support team.
(Updated 30th May 2003)
Support for rendering using a PURE card in a different
machine to the one running your 3dsmax or maya session
was added in version 1.4 of the PURE software. Enter
the host name or IP address of the workstation containing
the PURE card in the render panel in 3dsmax / VIZ
or Render Globals in Maya.
In version 1.3 or earlier of the PURE software
to render on a PURE card in a different workstation
to the one running your 3dsmax or maya session you
need to use a network renderer. 3dsmax and VIZ users
should use the network renderer supplied with 3dsmax
/ VIZ, see page 14-2 of the PURE user manual for
advice on setting this up. Maya users should use
a third-party network renderer such as Muster or
Smedge.
By default RenderDrive only saves the most significant
warnings in its log file. If you encounter a problem,
these FAQs or ART customer support will ask you
to change the settings to save more messages. To
do this:
Go to the web queue by entering the RenderDrive's
IP address in a web browser.
Click on the 'Log Settings' button.
On the 'Write to log file' line switch both 'Warnings'
and 'General info' on, then click on the 'SET'
button.
Re-render and a lot more messages will now be
written in the log file.
To see the log file press on the 'View Log' button.
If the text file appears jumbled, see page 13-5
of the RenderDrive user manual for instructions
on changing the program you use to view log files.
Be patient. If you are using a RenderDrive, switch
on logging of messages before you start rendering
- see 'RenderDrive log file
empty - switching on logging of warnings' above
Wait at least 10 minutes and then check the log
file. If there is a message starting 'RLC' see 'RLC
messages in log file or render progress' below.
If there is no RLC message, then seek further advice.
This is probably due to an RLC error - see 'RLC
messages in log file or render progress' below.
A message starting 'RLC' indicates a problem with
a core. The software tries to use the core for 6
minutes before switching it off and completing the
render with the remaining cores. (The AR250 chip
contains 1 core and the AR350 chip contains 2 cores.)
One or two cores make very little difference to
performance.
If you have a core that is persistently giving
an RLC error, then you can configure the system
to always ignore the core eliminating the 6 minute
delay at the start of each render.
The RLC message will look something like:
RLC 13 (13 / 64) => 63
This means that core 13 out of 64 has been switched
off leaving 63 cores.
PURE: Go to the Control Panel and bring up the
System panel. Swap to the Environment tab. Create
a new variable called 'AR250_USECHIPS' and set its
value to be '-' followed by the core you are switching
off. In the example above you would set its value
to be -13. Once you have pressed 'Set', reboot the
PC. If you have more than one core to switch off
use a comma separated list, e.g. if you are switching
off cores 3, 8 and 13, set the list to be '-3,8,13'.
RenderDrive: Edit the file called 'complete' on
the RenderDrive's floppy disk. If you are switching
off core 13, add a line to the end of the file:
export AR250_USECHIPS=-13
If you are switching off cores 13, 27 and 48, then
add this line to the end of the complete file:
export AR250_USECHIPS=-13,27,48
Make sure the file ends with a blank line and save
it. Put the floppy disk back in the RenderDrive
and restart the RenderDrive.
New 12 June 03
The edges of glass objects can appear black or
at least very dark. This usually occurs when light
rays are internally reflected. They will be traced
until they reach the maximum ray depth, then give
a result of black. You can see a very similar effect
if you look at a real glass object, so it is nothing
to be concerned about.
Revised 19 Jan 2004
If rendering stops with a message like 'Error
allocating space for picture', 'Couldn't load
picture source file' or 'Couldn't delete picture',
the problem may be that the file name and path
of a bitmap is too long or contains a lot of capital
letters.
To check this you need to look at the log file:
This is specific to RenderDrive / PURE software
releases 3.0-* and 3.1-0. It is fixed in releases
3.1-1 onwards.
The release containing the fix is being beta tested.
New 10th February 2004
PURE and RenderDrive support three types of motion
blur - camera motion blur, transformation object
motion blur and deformation object motion blur.
Camera motion blur - camera movements, including
zoom and field of view changes are motion blurred.
Transformation object motion blur - motion blur
of geometric objects that are moving without deforming.
Moves include translations, rotations and scales.
Deformation object motion blur - objects that are
deforming over time - for example a cylinder that
bends, the skin of a walking character.
All RenderPipe interfaces (Maya, max and RIB) support
both camera motion blur and transformation object
motion blur.
Deformation motion blur is supported by RenderPipe
for Maya and by RenderPipe RIB for objects which
are topologically constant. To be topologically
constant, the number and ordering of vertices must
not change during the movement. Typically a bending
cylinder would be topologically constant so would
have deformation motion blur, but the skin of a
walking character would probably not be topologically
constant so would not have deformation motion blur.
RenderPipe MAX does not support defamation motion
blur, because max does not generate suitable meshes.
