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VRay for 3ds Max Manual
V-Ray for 3ds Max Troubleshooting
For troubleshooting installation and licensing issues, please check the
installation PDF guide.
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This is most likely a hardware problem. V-Ray cannot cause system freeze
by itself. The worst that V-Ray can do is crash 3ds Max. Check your memory
chips and/or your CPU temperature.
The exact text in the message box may differ, depending on where in V-Ray
the error occurred. There are different reasons for this message to appear:
- Insufficient RAM - one of the most common reasons
for the unhandled exception. See the section on
Excessive
memory usage below for more details.
- CPU overheating or RAM defects - this is another
reason for unhandled exceptions that has become quite common recently
with the increased clock speed of moden processors. It is characterized
by random crashes during rendering and may be quite difficult to
distinguish from a software problem. Installing a CPU temperature
monitoring software and checking the RAM for defects may help to
determine whether the problem is in the hardware or the software.
- Crashes with motion blur enabled - A common problem
is when there are motion-blurred objects depending on one another; in
that case, hiding the original object and using a copy of it for
rendering helps.
- Using the native 3ds Max Skylight light type -
either on its own, or as a part of the Daylight system. If this is the
case, use V-Ray's own environment dialog to create the skylight effect.
- Incompatibility with other plugins - if you suspect
this is the reason for the error, please write to
vray@chaosgroup.com and to the
plugin vendor and explain the situation. Please
note that the problem might be in the plugin, and not in V-Ray.
Some plugins were specifically coded for the default scanline renderer
and may behave unpredictably with V-Ray.
- A bug in V-Ray - if you believe that this is the
problem, try to isolate it (if it occurs in a specific situation related
to a certain object, material, atmospheric effect etc.) and email the
file c:\vraylog.txt as well as the 3dsmax scene to
vray@chaosgroup.com
Like every other program, V-Ray needs a certain amount of RAM to render
the image. Depending on the scene complexity and the render settings, V-Ray
will use varying amounts of RAM. Sometimes, the available system RAM may be
less than the amount needed for rendering. In this case, you will most
likely get an unhandled exception. You can check the memory usage from the
Windows Task Manager.
On 32-bit machines, the Windows® operating system allows by
default up to 1.5 GB for any single process (application). That means that
even though you may have more physical RAM (for example 2GB), the operating
system will not allow an application to use all of that memory.
However, on the Windows® XP operating system, you can change
this by using the famous /3GB switch in your boot.ini file. This will enable
the OS to allocate up to 3 GB of RAM for any given application. Using that
switch may allow you to render your scene without using any of the methods
below for reducing memory usage.
On 64-bit platforms, the 64-bit version of the Windows®
operating system allows the usage of all available physical memory without
limitations.
If you cannot use any of these methods to allow more RAM for rendering,
the only choice is to reduce the amount that is needed by changing your
scene and your V-Ray settings.The scene elements that take up most of the
RAM while rendering can be divided into the following groups:
- Geometry - scenes with lots of objects and/or
triangle counts require more memory to render. There are several ways to
reduce this amount:
- Adjust the
raycaster settings in the
System rollout (reduce Max. levels,
increase Min. leaf size, increase
Face/level coefficient, switch from
Static to Dynamic
Default Geometry).
- If all else fails, use
VRayProxy objects.
- Mapping UVW channels - in 3dsmax, every mapping
channel takes up the same or larger amount of RAM as the geometry
itself. Unused mapping channels can increase RAM usage dramatically,
while not affecting the scene in any way. In recent 3dsmax versions,
texture channels are generated by default for all objects when they are
created. V-Ray has no control over RAM usage for texture coordinates -
you will have to make sure that only the channels you need are actually
present in the scene. Using
VRayProxy objects is also a solution since in that case texture
coordinates are also cached to disk along with the actual geometry.
- Displacement mapping - objects displaced with the
2d displacement mapping method may require a lot of RAM to render,
especially with large displacement maps. If this is the case, use the 3d
displacement mapping method. Also, if you have several distinct
displacement modifiers with the same displacement map, it is better to
replace them with one modifier, applied to all the necessary objects.
This is because each modifier will take RAM for the displacement map,
separately from other modifiers, even if they have the same map.
- Bitmaps - these tend to take up large amounts of
RAM, especially if the maps are large. Since textures are managed by
3dsmax, V-Ray has no direct control over their memory usage. However,
you can use the Bitmap pager settings of 3dsmax to reduce the RAM taken
up by bitmaps. For more information, consult your 3dsmax documentation.
- Bitmap filtering - Summed area
filtering uses much more memory than Pyramidal
filtering.
- Shadow maps - these may also take up significant
amounts of RAM. Again, these are managed by 3dsmax and V-Ray has no
direct control over their memory usage. To reduce memory usage, you can
switch to raytraced VRayShadows instead.
- Image buffer - large output resolutions require a
significant amount of RAM to store the final image. Additional G-Buffer
channels increase that amount. There are several ways to reduce this
amount:
- Use the 3dsmax Bitmap pager, if you are rendering to the 3dsmax
default VFB.
- If you use
V-Ray's own VFB, use the Render to V-Ray
raw image file option and then use the V-Ray raw image file
viewer to convert the resulting file to a different format.
- Render the image in several different passes and stitch the
pieces in a compositing program.
- Image samplers (AA) - the image sampling algorithms
of V-Ray require some amount of RAM to hold all the data for the sampled
image. This amount can be quite large, depending on the chosen bucket
size and sampling rate. To reduce that amount:
- Reduce the bucket size.
- Switch to a different
image sampler - for example, the Adaptive
DMC sampler uses less RAM than the
Adaptive subdivision sampler.
- Global illumination caches - irradiance maps,
photon maps and light maps all require additional memory to store them.
Each of these has different methods for controlling its memory usage:
- For the
irradiance map - the memory depends on the number of samples in
the map; you can reduce this number by using lower
Min/Max rate, and more loose
threshold values (higher Color threshold,
higher Normal threshold, lower
Distance threshold).
- For the
photon map - the memory depends on the number of photons stored.
You can reduce this number by reducing the Diffuse subdivs for the
lights, or by increasing the Max. density.
- For the
light map - increase the Sample size.
- 3dsmax scene - 3dsmax itself stores a lot of
information about the scene. V-Ray has no control over that memory, but
here are some things you can do to reduce it:
- Collapse modifiers to editable meshes
- Cache animations with a PointCache modifier
There may be several reasons for splotches when rendering with the
irradiance map:
- Regular noisy splotches - these are usually a
result of insufficient Hemispheric subdivisions
for the irradiance map. Usually they appear in difficult lighting
situations when the default setting is too low. Examples of difficult
lighting conditions are small bright sources of indirect light, hdri
environments etc. You can avoid these splotches in several ways:
- If you are using Quasi-Monte Carlo GI for secondary GI bounces,
try using another method - the
light map or the
photon map.
- Increase the Hemispheric subdivisions
for the irradiance map. Note that the effect of the increased
subdivisions depends also on the settings of the
DMC sampler.
- Decrease the Noise threshold of
the
DMC sampler.
- Isolated bright splotches - there may be different
causes for these:
- GI caustics - if you have reflective or refractive surfaces in
your scene, especially if they are glossy, V-Ray may try to compute
the GI caustics for these surfaces. Since caustics usually require a
lot of sampling to get right, there may be splotches.
- Incorrect or missing UVW coordinates - if some objects in your
scene lack UVW coordinates, or the UVW coordinates fall outside the
texture map, this can produce splotches or weird colors in the
irradiance map. The solution would be to apply correct UVW
coordinates to those objects.
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