Cache Files
In this tab you will find numerous settings that let you save and re-use cached data. While GI is being calculated, the Project is analyzed and pre-calculations are set up whose results (caches) can be saved as files. When a Project is re-rendered, existing caches can then be reloaded instead of calculating these anew, which saves enormous amounts of render time!
The cache settings for the specific GI method selected will be made available. These methods allow caches to be saved/loaded:
- Irradiance Cache
- Radiosity Maps
- Light Maps
The following basic rule applies to saved/loaded cache files: They can only be used for a non-modified project. As soon as crucial geometry, materials, lights or even GI settings are modified, the data saved in the cache file will no longer be valid and a new cache should be calculated. Otherwise faulty renderings will result.
However, there are several exceptions to this rule. Certain settings that are not crucial for lighting situations in the cache, like those that were subsequently rendered, for example: output size (Light-Maps with Scale set to Screen are restricted to a specific output size), post effects and similar features can be fine-tuned with no problem. When in doubt, delete the existing cache and calculate a new one.
Otherwise, tricks can also be used, e.g., adding a different background or sky - as long as it doesn’t affect the lighting situation too much.
There is a difference between camera animations and full animations (see also GI and Animations).
Information about cache files in conjunction with Team Render can be found here. The following basically applies: If Team Render should use cache files, the cache files must also be uploaded.
Irradiance Caches
Contrary to Radiosity and Light Maps, cache entries can be calculated and saved for different camera views for Radiosity and Light Maps. Let’s assume you change the angle of view for a given Project. If you already saved a cache, you will only have to calculate the entries for the newly visible parts of the image - which of course is much faster (Auto Save and Auto Load must be enabled and rendering is done to the Picture Viewer).
Clicking on this button will flush (delete) all previously saved caches. This should be done for the above-mentioned project modifications to avoid incorrect results. If the Auto Load option is disabled, the cache does not have to be flushed because there are no caches that can be loaded.
At the right of the button, information is displayed regarding any matching saved caches that have been found.
Prepass Only
Skip Prepass (If Present)
These two options are primarily designed for tricks like the following: Assuming you want to render a camera animation (light situation is constant, i.e., no animated objects, materials or lights). You can, for example, calculate only every 5th frame (see Frame Step) or a small temporary output size for the prepass and then lock the actual cache (Skip Prepass (If Present) option) for rendering so Cinema 4D has to make do with what is available. Most often, the quality will nevertheless be sufficient.
- Prepass Only: If enabled, the IR prepasses will be calculated without rendering the final image. Auto Save and Auto Load should also be enabled with this option. Skip Prepass (if Present): If enabled, a cache file must be present. You should only use this option if you are absolutely sure that the existing cache file harmonizes perfectly with the current GI settings and nothing has been modified in the Project. Otherwise faulty rendering will result.
Note that this feature works best in conjunction with QMC and IR modes.
If a cache file has already been saved using the Auto Save function, this option will load that file. If no cache is present, a new cache will be calculated. If enabled, this option defines for Team Render and Team Render Sever renderings whether or not existing cache files should be distributed to the Render Clients.
If enabled, the cache file will automatically be saved. If no separate save path is defined, the file will be saved to a folder named ,illum’ in the Project’s save path by default. The file will be named as follows: ,Filename.gi’. If a cache is calculated for each frame of animation (Full Animation Mode enabled), files will be named as follows: ,Filename0000x.gi2’. The following applies to rendering stills: When using Team Render make sure that the corresponding options are enabled. Otherwise no cache can be saved by the server for rendering.
This option must be enabled if your Project contains animated, changing light situations (i.e., animated objects, materials or lights). A cache will be calculated for each frame of animation which are self-contained and independent of each other. Contrary to IR versions prior to R15 in which various pre-passes and a lot of render time were required to calculate one and the same cache for the entire animation, the new version requires only a reasonable amount of render time (which unavoidably becomes longer as the animation progresses). If the Record Density is high enough, flickering can still be prevented.
When saving caches, note that the Full Animation Mode generates numerous files that can require a great deal of memory!
Radiosity Maps
Similar to Irradiance Cache, Radiosity Maps can also be saved and re-used when the Project is rendered again.
When certain GI modes are combined (imagine IR+LM (Build Radiosity Maps enabled in the Light Mapping tab)), an entire cache cascade is calculated: consecutively one LM cache then a Radiosity Map cache and finally an Irradiance Cache. If you already calculated and saved all three caches and enable Auto Load for Irradiance Cache when you re-render, this option should also be enabled for the other caches. Otherwise these will be re-calculated unnecessarily, which is something that is normally not desired.
The following applies to the modifiable Light Mapping option Build Radiosity Maps: Because Radiosity Maps can become relatively large compared to Light Maps, it is recommended that the latter be saved (and loaded), and Radiosity Maps be created ,on-the-fly’ without saving them. This method is very fast and doesn’t stuff your hard drive full of potentially huge files.
Clicking on this button will flush (delete) all previously saved caches. This should be done for the above-mentioned project modifications to avoid incorrect results. If the Auto Load option is disabled, the cache does not have to be flushed because there are no caches that can be loaded.
At the right of the button, information is displayed regarding any matching saved caches that have been found.
If a cache file has already been saved using the Auto Save function, this option will load that file. If no cache is present, a new cache will be calculated. If enabled, this option defines for Team Render and Team Render Sever renderings whether or not existing cache files should be distributed to the Render Clients.
If enabled, the cache file will automatically be saved. If no separate save path is defined, the file will be saved to a folder named ,illum’ in the Project’s save path by default. The file will be named as follows: ,Filename.gir’. If a cache is saved for each frame of animation (Full Animation Mode enabled), the files will be named as follows: ,Filename0000x.gir’. When using Team Render make sure that the corresponding options are enabled. Otherwise no cache can be saved by the server for rendering.
If this option is enabled, the cache for each frame of animation will be rendered anew and saved with a unique (sequential) name. If this option is disabled, a single cache will be used for the entire animation (if Auto Save and Auto Load are enabled). The latter will only work with camera animations!
If this option is enabled in conjunction with Team Render: The server will not distribute any cache files; each client will calculate its own cache.
Note that numerous files are created by the Full Animation Mode when saving caches, which can require a great deal of memory!
Light Mapping
As with Irradiance Cache, a Light Mapping cache can also be saved for later use. A single cache can be used for camera animations (Full Animation Mode disabled). All flickering in Light Maps during animation can be eliminated. Make sure to also enable the Use Camera Path option. This works best if Scale is set to
Clicking on this button will flush (delete) all previously saved caches. This should be done for the above-mentioned project modifications to avoid incorrect results. If the Auto Load option is disabled, the cache does not have to be flushed because there are no caches that can be loaded.
At the right of the button, information is displayed regarding any matching saved caches that have been found.
If a cache file has already been saved using the Auto Save function, this option will load that file. If no cache is present, a new cache will be calculated. If enabled, this option defines for Team Render and Team Render Sever renderings whether or not existing cache files should be distributed to the Render Clients.
If enabled, the cache file will automatically be saved. If no separate save path is defined, the file will be saved to a folder named ,illum’ in the Project’s save path by default. The file will be named as follows: ,Filename.gil’. If a cache is saved for each frame of animation (Full Animation Mode enabled), the files will be named as follows: ,Filename0000x.gil’. When using Team Render make sure that the corresponding options are enabled. Otherwise no cache can be saved by the server for rendering.
If this option is enabled, the cache for each frame of animation will be rendered anew and saved with a unique (sequential) name. If this option is disabled, a single cache will be used for the entire animation (if Auto Save and Auto Load are enabled). The latter will only work with camera animations!
If this option is enabled in conjunction with Team Render: The server will not distribute any cache files; each client will calculate its own cache.
Note that numerous files are created by the Full Animation Mode when saving caches, which can require a great deal of memory!
File Location
If you want to save your GI caches to a specific location, enable this option and select a path to which to save. Otherwise, these files will be saved to a "illum" folder in the Project’s directory by default.