Light map (cache) importance

Light maps can be very useful and, depending on the type of render, mandatory.

General purpose and usefulness

Light maps store all the indirect lighting values used for your type of lighting setup: Final Gather, Irradiance, Photon, Caustic, etc.

Render time

If you are using any type of Indirect Lighting as mentioned above, then prior to rendering, the light points must be calculated. Depending on your scene this process can take just a few minutes or several hours. Generating a light map (or cache as it is sometimes called) on your local workstation and uploading that to Render Rocket will allow all servers to read directly from that file. In doing so, the calculating process is reduced significantly resulting in a much lower render-time and saving you money on the render.


When it becomes a necessity

 Strip Rendering / Region Rendering

If you are rendering a large single frame image using 3ds Max Strip option or Maya's Region Rendering, always be sure to run a test first. If you notice your final image has slight differences in the lighting between each strip, then a light map will be required. The light differences you see is the result of each server calculating the light bounces slightly differently. Having a light map allows all servers to read from the same file ensuring that light is even throughout all strips.


Just like above, or anytime you submit a new scene file, a test render is always suggested. If your animation comes back and you notice "flickering" during playback, this is the same result as mentioned above; each machine calculating the light slightly differently. Uploading a light map allows all machines to render the light exactly the same resulting in a smooth animation. (Not to mention saving you money!)

Unfortunately, each scene is created differently. Without running a small test first, there is no way for us to know whether your particular scene will require this.

The links below are from outside sources that give an explanation on how to generate and save the light maps for Maya ands 3ds Max.


Generating a FG map in Maya

Generating a IR map in 3ds Max


The same methods described in the links above can be translated to other types of light maps for the software.


Instructions for preparing the scene with a light map for Render Rocket


  1. In the Render Settings > Indirect Lighting tab, change the "Rebuild" mode to "Freeze". This tell Maya to use the light points in the specified file.
  2. In the map field remove any absolute path you have set (if any). You want the path to be relative, meaning ONLY the file name.

3ds Max

  1. In the Render Settings > Indirect Lighting, change the Mode to "From File"
  2. In the map field remove any absolute path you have set (if any). You want the path to be relative, meaning ONLY the file name.


If you use an absolute path, then our network will not be able to find it. ALWAYS use relative paths when possible


Relative: "Scene01.fgmap"

Absolute: "C:\users\mike\documents\maya\projects\chevy\Scene01.fgmap"



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