Light Collab / Help Documents / Creating a Vue atmosphere sphere

Creating a Vue atmosphere sphere
The first step obviously is to create the atmosphere. For help on doing that you should read this. The basic workflow would be to do test renders from several views. For these you would use the standard camera, rotating it to get the views you want. Once you are happy, you can then export your sky with the following workflow.

I. Spherical Camera Setup

    Before you render out your atmosphere sphere, the camera needs to be flattened, otherwise the horizon line will be warped as illustrated in the following image:

    In addition to zeroing out the camera, we also want to do the same for the sun so that it will appear in the middle of the panoramic image. To do this we will set the yaw and roll to zero and only raise or lower the pitch depending on how high we want to have our sun in the sky. So in sum:

    Camera:
       pitch=90
       roll=0
       yaw=180.

    Sun:
       pitch=variable
       roll=0
       yaw=0

    Next we open the render settings dialog and check "panoramic view" and "spherical render."

II. Multi Pass Render

    Next "enable multipass" and click the edit button. This will open a new window:

    Here we want to choose "cloud mask" and chose a file name and render in EXR. For the EXR options you want 16 bit float with ZIP 1-scanline compression. This will render out a mask we can use to separate the cloud from the sky (see the Nuke section below). We can get a render of the sky itself by turning off the cloud(s) in the Atmosphere Editor and rendering that out with a different name.

    Note: You'll want to uncheck both of these above naming tickboxes when doing test renders so you don't accidentally overwrite your saved images!

III. Gamma and Linear Workflow

    We are rendering in EXR meaning we will be keeping our images linear but displaying then in sRGB color space. We therefore need to set the gamma properly in Vue. To do this we first need to open the Post Render Options window and ensure that everything is off. (This includes auto-exposure and natural film response!).

    Next we click on the gamma button in the Post Render Options window (circled above in red). This will open the Gamma Settings window where we set the following options:

    This means our EXR images stay in linear color space (1.0) but are displayed in Vue in sRGB color space (2.2). Because this mirrors what Nuke does, we will get a one to one correspondence between the two software.

IV. Maya and Nuke

    The resulting images will map perfectly onto a Nuke sphere node (the Maya primitive sphere had issues with both the UVs and the rotation, so don't use it). You can export the sphere as an OBJ into Maya if desired using the writeGeo node. You'll want to give the sphere a large radius like 10,000 (this depends on your scene scale, but the sky is pretty big!). You can then import your cameras (as an FBX) from Maya and read this all into Nuke like this:
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