CG & VR Part 2 – VR Rendering in Maya

CG & VR Part 2 – VR Rendering in Maya

Finally, Part 2 has arrived! It’s time to start learning how to render CG scenes as equirectangular stereo-spherical images using Maya!

The purpose of the following tutorial is to give you some of the basic knowledge to get you up and running with some results in the least amount of time. While there are other methods for rendering stereo-spherical content, I chose the software I’m using because they currently seem to provide the most turn-key solution.

Hopefully you’ve taken a look at Part 1 to get a general idea on how stereoscopic-spherical cameras work in the realm of CG, but you’ll be able to follow this tutorial without any trouble if you haven’t.

Elijah Butterfield
Elijah Butterfield – Intern

 

Software:
Maya 2016 – Modeling (There’s a Free 30-Day Trial)
Mental Ray for Maya – Rendering
Domemaster3D Maya Plugin – Stereo-Spherical Camera Creator
Photoshop – Combining Rendered Images into Over-Under format (Again, there’s a Free 30-Day Trial)
Firefox Nightly – VR Enabled Browser to view our Renders

Downloads:
Photoshop Over Under Formatter Action

 

Once you have you have these resources downloaded and set up, you’ll be ready to start!

If you already have a scene put together, feel free to use that. In my case, I’ll be using a scale model (accurate down to the quarter inch, as they say) that I made of our office space.

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The Office – WIP

 

 

Step 1 – Camera

Our first step is to create our stereo-spherical camera rig.

To do this, select the Rendering Menu, then select Domemaster3D > Dome Cameras> LatLong Stereo Camera

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You’ll now see that a set of three cameras has appeared in the center of your grid, this is our spherical-stereo camera rig. Notice that the cameras appear very small in relationship to my scene, this is because I have my scene’s units set to Feet instead of the default Centimeters. If you have encounter this, you can increase the size of your cameras without altering the camera’s separation by increasing the Cam Locator Scale setting in the Channel Box.

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Step 2 – Camera Settings

Now lets open up the Attribute Editor and take a look at some of the basic settings we can tweak on our camera rig.

With the camera rig still selected, open the Attribute Editor, navigate to the Center_LatLog_Stereo tab > select the LatLong Stereo Shader section.

 

Field of View: These sliders control what range of the scene the camera will render in the X (Horizontal) and Y (Vertical) axis. I’m going to leave these at default, because a 360° x 180° image is what we’re trying to achieve.

Camera Separation: This slider determines the distance between the left and right cameras. In most circumstances, you want this to be the average interpupillary distance of 2.5 inches (In my case, 0.212 decimal feet).

Zero Parallax Distance: The Zero Parallax Distance is located where the cameras’ lines of sight converge, aka, the Focal Distance.

Objects located at the Zero Parallax Distance will not have any 3D effect, while objects located in front the the Zero Parallax Distance have Positive Parallax and will appear to pop out of the screen, and objects behind the Zero Parallax Distance have Negative Parallax and will appear to be further away.

I have this attribute set to 20 Maya Units, which equates to 20 Feet with my current settings.

Zenith Mode: Leave this box unchecked for now. This setting allows our camera rig to work in either a horizontal (unchecked) or vertical orientation (checked).

 

 

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For full documentation of the Domemaster 3D plugin, please take a look at the Domemaster 3D Maya GitHub Wiki pages.

Now that we have our camera rig all set up, it’s time to see the fruits of our labor. Let’s configure our render settings!

 

Step 3 – Rendering

The first thing we need to do is tell Maya which camera we want to render with.
In the Rendering Menu, select Render > Render Settings.

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In the Render Settings Window, select Renderable Cameras > Renderable Camera > LatLongStereoCameraX (Stereo Pair).

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Now we need to set the resolution for the images that are going to be output.
The standard aspect ratio for stereo-spherical images is 2:1. However, we’re going render each eye in a 4:1 aspect ratio instead and then stitch them into a 2:1 image in post. Rendering in 4:1 instead of 2:1 cuts our rendering time in half and saves us from having to scale the images later on, which is typically a lossy process.

Here are a few 4:1 resolutions to try:

1k Image – 1024 x 256 per eye
2k Image – 2048 x 512 per eye
4k Image – 4096 x 1024 per eye
8k Image – 8192 x 2048 per eye

 

In the Render Settings Window, select Image Size and enter your desired resolution in the Width and Height dialogue boxes.

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In the Rendering Menu, select Render > Batch Render.

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Once the render is complete, your left and right images will be in two separate folders located in the images directory of your Maya Project folder.
In Windows, the default location is C:UsersUserNameDocumentsmayaprojectsdefaultimages

You should have two images like the ones below.

Lefty
Left Image
Righty
Right Image

 

 

Step 4 – Combining Images

Now we’re going to move into Photoshop to combine the two images into the Over Under format. Keep in mind that Photoshop is not required for this step, and you can use other image manipulators such as Gimp to achieve a similar outcome.

To simplify the Over Under formatting process, I’ve put together a quick Photoshop Action that will format and save our image for us.
You can download it here if you haven’t already.

 

With Photoshop open, press Alt+F9 to open the Actions Pane, click the pane’s Menu Button, and then select Load Actions.

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Navigate to where you saved the Action file (VR Stuff.atn), select it, and click Load.

You’ll now see that there is a folder named VR Stuff in the Actions Pane, and inside that folder is an action named Over Under.

 

Select the Over Under Formatter action and click the Play Button to start it.

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You will now be prompted to open an image file. Navigate to where your Maya renders are saved, select the left image, and click open. Once you’ve done this, you will be prompted again. Select the right image and click open.

After a few moments, you’ll see the images have been put placed in the Over Under format. Save your image.

Combined

 

 

Congrats, you’ve just (hopefully) rendered out your first stereo-spherical image! Now go grab your HMD, open up Firefox Nightly (or just regular Firefox if you’re using a phone and Google Cardboard), and navigate to the eleVR Picture Player so you can take a look at your render in all of its stereo goodness.

 

Once you’ve made your way to the Picture Player, click on the Folder icon in the bottom left corner, navigate to the image you saved from Photoshop, click Open . 

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Click the Equirectangular Menu, select Equirectangular 3D from the list.

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If you have your HMD already set up, you should now be able to bask in the glorious spectacle of what you have just achieved.

 

CG & VR Part 3 – Spherical Compositing in Maya