How To: Generate V-Ray Irradiance Maps, Light Caches, and Photon Maps on the ResPower Super/Farm™

Overview

The ResPower Super/Farm™ proudly supports 3dStudio Max rendering using the "V-Ray" render engine. This tutorial discusses how to use the ResPower Super/Farm™ to generate V-Ray irradiance maps, light caches, and photon maps, in all supported 3dsmax versions. This tutorial was written using V-Ray 1.5 RC3 but the concepts should be similar for any version of V-Ray.

It is important to note that generating an irradiance map is done in series for each scene, not in parallel. That is, exactly one computer will be used and you will see no acceleration. What is the benefit, then? First, you keep your computer free to continue working on your next scene. Second, if you have a number of scenes, you can produce each scene's irradiance map in parallel with the other scenes. That is, there is no requirement that you produce one irradiance map at a time, just that each job producing an irradiance map is working in series.

This process is somewhat complicated, but will produce an irradiance map cache file that will help to accelerate the rendering of longer sequences. You should be familiar with the process of submitting a standard .max file to the farm before proceeding. The tutorial for that is available here . The basic steps are:

• Configure V-Ray to produce an irradiance map file.
• Save and upload this scene as "vrmap-generate.max".
• Configure V-Ray to use an irradiance map file.
• Save and upload this scene as "vrmap-use.max".
• Render "vrmap-generate.max" to generate an irradiance map file.
• Move the irradiance map to /source/ folder
• Render "vrmap-use.max."

Configure V-Ray to produce an irradiance map

Configure V-Ray to Render: These are the settings you should use to generate an irradiance map.

On the Renderer tab, go to VRay:: Irradiance map -> Mode, and select "Multiframe incremental". Go to VRay:: Irradiance map -> On render end, and turn on "Don't delete," "Auto save:", and "Switch to saved map." Choose the "Browse" button to provide a file name to save to. Be sure that the file name you select is in the folder "C:\respower\temp\max\output\" For example, a good V-Ray map filename looks like this:

Save and upload this scene as "vrmap-generate.max"

Save this file and upload it according to the directions here . Be sure that you follow a convention to help you distinguish this file from the one that you will create in the next step. We prefer to append "vrmap-generate" to the file name, so that a complete file name might look like this:

Configure V-Ray to use an irradiance map file.

On the Renderer tab, go to VRay:: Irradiance map -> Mode, and select "From File". In the File: edit box, type in the name you chose to save your irradiance map to, but this time, change the folder name from c:\respower\temp\max\output to c:\respower\temp Continuing our previous example, you would change this file name:

Save and upload this scene as "vrmap-use.max"

Save this file and upload it according to the directions here . Be sure that you follow a convention to help you distinguish this file from the one that you will create in the next step. We prefer to append "vrmap-use" to the file name, so that a complete file name might look like this:

Render "vrmap-generate.max" to generate an irradiance map file.

It is important in this step that you force the render to occur on a single render node. This will ensure that you get a single irradiance map file that will work with your vrmap-use.max file.

To do this, you'll need to use a little bit of math. Suppose you have 250 frames to render in your final sequence, and you want every 25th frame to be used to process the irradiance map. This means that you want to have 250 / 25 = 10 frames processed to produce the map. In the Render Wizard, set up your render as a simple animation, no split frame, set the "Frame Step" option to 25, and the "Frames Per Task" option to a value greater than 10. Why a value greater than 10 and not 10? It is very common for trivial counting errors to occur in this procedure. For example, if your scene starts at 0 and stops at 250, a frame step of 25 will actually process 11 frames. By choosing a "Frames Per Task" option higher than the result of the frame count divided by the "Frame Step," we guarantee that only one task will be used to produce the irradiance map.

Note also that you can and probably should reduce the resolution of your render for this stage using the "Width" and "Height" options.

We normally do not recommend modifying the "Minimum System Requirements," but for this process, it is critical that you set them to the maximum, because it is a serial process and you don't want it running on an older machine.

Finally, since it is likely that this process will take more than the time limit afforded by a subscription, you will probably want to use "Metered Service" as the billing model for this job.

Render "vrmap-generate.max" to generate an irradiance map file.

Once the task of generating the irradiance map is done, the farm will place the map into your /renders/<job-number> folder, where <job-number> corresponds to the job number assigned by the Render Wizard.

If you used "Metered Service," choose "Pay for Output" from the Job Status page to pay for the output, which includes the irradiance map. If you do not pay for the output, you will get a Permission Denied error when you attempt to enter the folder in your FTP client.

Using your FTP client, move the .vrmap file from your rendered output folder to your /source/ folder. Alternatively, use the "Contentize Output" command on the Job Status page, which will move the /renders/<job-number> folder into your content directory.

Proceed back to the Render Wizard, and submit the vrmap-generate.max file. Be sure to select the irradiance map in the Super/Cache section. This will cause the farm to copy the irradiance map to each render node's c:\respower\temp folder prior to launching 3dsmax.