For troubleshooting installation and licensing issues, please check the installation PDF guide.
If you experience any problems not discussed below while using V-Ray, please write to email@example.com
My system locks up and freezes while rendering
Excessive memory usage while rendering
I get splotches in my rendering when using the irradiance map
Search Keywords: problems, troubleshooting, bug
This is most likely a hardware problem. V-Ray cannot cause system freeze by itself. The worst that V-Ray can do is crash Rhino. Check your memory chips and/or your CPU temperature. If the crashes are limited to Rhino only and not the OS or computer please see "Excessive memory usage while rendering" below.
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:
- Bitmaps - these tend to take up large amounts of RAM, especially if the maps are large.
- 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 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.
- Rhino scene - Rhino itself stores a lot of information about the scene. V-Ray has no control over that memory, but you can adjust the quality of render meshes to reduce it.
- Enable DR - If you have access to mutiple computers you can take advantage of V-Ray's Distributed Rendering feature or DR to borrow power from other comptuers on the LAN to assist with rendering. DR is enabled in the options menu under the System rollout.
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 Deterministic 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.