01. Introduction

In this lesson, you’ll learn how to render using V-Ray’s Interactive Production Renderer. Not to be confused with V-Ray RT, IPR allows us to use our CPU to render out scenes with live updates. This feature makes lighting and material tweaks faster, and easier to accomplish without the need to stop your render.

02. Adjusting Render Settings

Typically, we want to use some reduced render settings since these renders are meant for the working phase of our projects. Even though IPR forces your render settings to use its Progressive Image Sampler, there are still a couple settings we should pay attention to!

Let’s walk through a couple sections of the render settings dialogue box (shortcut: F10) and go over why they are or are not important for this workflow. The assignment scenes will already have the render settings setup for you, but I will also cover how to load up a render presets. The preset is based off the same settings covered in this lesson.

Open up the Render Settings in 3DS Max to follow along.

Common Tab

  • Output Size – By default the resolution is irrelevant when using IPR because changing the scale of the frame buffer (the window that appears when you start a render) changes the resolution of your render.
  • Options – We find it useful to turn off displacement in this tab when working on complex scenes. Displacement also needs to be turned off in the V-Ray tab under Global Switches, but we will cover that below. I will be leaving mine on.

V-Ray Tab

  • Global Switches – This is the second spot where displacement needs to be turned off if desired. If you’re trying to see what displacement looks like on an object, you should obviously leave this checked in both areas. I will be leaving mine on.
  • Image Sampler – As mentioned above and in the V-Ray documentation, IPR forces Progressive even if Bucket is set. Progressive calculates the image as a whole, and reduces the noise for the entire image over time; if a time limit (Render Time, next section) is not set, the render will finish once it meets the appropriate Noise Threshold. This allows us to get a quick look of our render overall.
  • Progressive Image Sampler – These settings control some of the settings mentioned above. The subdivs can be left the same, since these are universal settings that work well in nearly every Progressive scenario.

Render Time (Min) can be used to set a time limit to your renders. When this number is set to ‘0’ it will keep rendering until the Noise Threshold is reached. You can also stop the render when you feel it looks good enough.

Noise Threshold can be set to .02, but you’ll be using IPR for making quick changes to regions of your render. You will either change something (which restarts the render) or stop IPR long before this is reached anyway.

GI Tab

  • Primary Engine – This should be set to Brute Force, and nothing else needs to be set for this.
  • Secondary Engine – This should be set to Light Cache; under the Light Cache rollout, set the Subdivs to 300. Since Light cache is the first thing to calculate, we don’t want this to slow us down. With a basic studio/HDRI environment and just rendering for testing purposes, the Light Cache doesn’t need to be set to anything high.

Settings Tab

  • IPR Options – Here you can change whether you want the VFB’s (V-Ray Frame Buffer aka the render window) scale to impact the resolution of your render. I recommend keeping this on because it comes in handy, but it’s really a matter of preference. This is enabled by default.

Also, Force Progressive Sampling is on by default and should be left that way. Using bucket for IPR just doesn’t make sense, so this is sort of a fail safe.

Render Elements Tab (Not Shown)

There isn’t really anything different in this tab that pertains specifically to IPR.

03. IPR Render Preset

a. Copy the .RPS file
First, copy ‘IPRPrset.rps’ to one of your local folders.

b. Load the Preset
You can load the preset from your render setup window, by clicking on the dropdown under Preset.

When prompted to select the Preset Categories, click load as they are already highlighted for you. When creating your own render presets, you can choose what you want to be saved. For example, this render preset will only change the V-Ray / Global Illumination Settings and the Common settings; however, presets can also include Environment Settings, Effects, and Render Elements.

None of these are necessary to change for this preset, so I left them out.

04. Rendering with IPR

a. Starting your IPR Render
In the scene you’re currently working in, open up the V-Ray Frame Buffer. So far, you’ve probably been using the normal render functionality (image on the left.) In order to activate IPR, you can use the Teapot Icon (Image on the right) with the green play button on it.

Once you click on this button, your render should start up as usual. Typically 3DS Max is completely locked from any changes being made; however, now you can continue to make adjustments to several components of your scene.

b. Locking View to Render
Traditionally, you click the viewport you want to see before clicking render, but now that the render is constantly being updated you’ll notice that clicking in other viewports will change your render camera. To prevent this issue, go to the Render Setup window and click the padlock icon next to view to render once you’ve set it to your render camera.

Now you’ll be able to move around in your perspective view without the render camera changing on you.

05. IPR Features

The options below (except for Render Regions) are all accessible by right-clicking on the VFB while IPR is running.

a. Render Regions (Button: )
Regions will automatically update as they’re drawn on a render. This allows you to easily spot check several parts of your scene without ever having to stop your render.

b. Real Zoom
Instead of zooming in on the pixels of your render, real zoom turns your mouse wheel into a camera zoom (without moving the actual camera.) RMB (Right Mouse Button) with IPR running and select Real Zoom to activate. To zoom in/out, mouse wheel forward and back. Use MMB (Middle Mouse Button) to Pan around.

See GIF on the right.

c. View Navigation
This option physically moves the camera using the VFB instead of the view port. Unlike real zoom, this really is changing where your camera is placed in the scene. Turning this tool off does not return the camera to its original location; however, clicking in the viewport will allow you to use undo (CTRL + Z) up to the max undo levels (default of 20) you have set.

d. Re-Initialize
Manually restarts the render, but takes in account for certain changes that wouldn’t normally affect IPR. For example, if displacement values are changed, they will not update automatically; the render needs to be reinitialized for certain changes like displacement, render settings, etc.

e. Select Object
Pretty self explanatory. When this option is active, it allows you to LMB on objects in the render to make selecting easier in busy scenes. I personally don’t use this very often.

f. Get Object Material
When active, this option allows you to LMB to select materials in the VFB which will then open in the material editor. If the material editor isn’t open, it will open it for you. Also, it will create a new tab view to keep your selections separate from your current working space. See GIF below:

g. Set Focus Distance
This feature isn’t currently supported with the version of the V-Ray camera that we use. This feature allows you to click on objects in the VFB to determine where the focus is in the scene.