Starglobe Tool

Andrew Hazelden edited this page Jun 7, 2017 · 7 revisions

Table of Contents

Introduction

The starglobe feature makes it easy to create starry sky backgrounds. The starglobe uses a specially prepared spherical shape that uses a unique all polygon quads based geometry. This eliminates the issues caused by pinch points on a typical NURBS or polygon sphere.

Domemaster3D includes extra resources to help you get started with fulldome and 360VR production such as .ma, .max, .fbx, and .obj meshes and a set of custom starglobe texture maps.

3DS Max Starglobe

3DS Max Starglobe

The Starglobe has been completely redone for 3DS max. There is a "starglobe_mesh_2K.max" and "starglobe_mesh_8K.max" version of the starglobe that can be found in the folder: C:\Program Files\Domemaster3D\sourceimages

This updated model fixes the self-illuminating texture issue that was present in previous 3DS Max releases. I would like to extend a special thanks to Roberto Ziche for looking into the issue and providing a solution.

Softimage Starglobe

Softimage Starglobe Toolbar

A Starglobe is available in the Domemaster3D for Softimage toolbar.

The default texture applied is a 2K resolution starglobe texture map. You can upgrade the default 2K texture map to an 8K texture map by linking in the starglobe_quadsphere_8k.jpg file that is stored in the Softimage Addons folder:

C:\Users\<username>\Autodesk\Softimage_<version-number>\Addons\domemaster3D\Application\bitmaps

Maya Starglobe

The starglobe tool is visible in the Maya shelf and allows a Maya user to create a night sky backdrop with only a few clicks.

Maya Starglobe Shelf

When you run the starglobe tool you can use the Attach to Camera options menu to select a camera in your scene. This menu item will cause the starglobe mesh to be point constrained to your fulldome camera rig.

This point constrain technique creates the impression of an infinitely large starry backdrop by causing the starglobe to follow the camera around the scene. The point constraint still allows you to rotate the view freely around the night sky backdrop using the standard Maya view navigation tools.

Starglobe tool

The new starglobe tool is based upon Jason Fletcher's starglobe texture map that is explained on the blog post "Stars to Surround the Scene":

http://thefulldomeblog.com/2013/06/22/stars-to-surround-the-scene/

Starglobe Resources

Models

The starglobe models are stored in the C:\Program Files\Domemaster3D\sourceimages folder on Windows.

The model "starglobe.obj" is an all quads based polygon sphere with a custom UV layout that is optimized to avoid texture pinching at the poles.

The model "starglobe_mesh.ma" has the same geometry as the "starglobe.obj" model but is stored in a Maya ASCII file.

quadsphere mesh

Textures

The starglobe textures are stored in the C:\Program Files\Domemaster3D\sourceimages folder on Windows.

The texture map named "starglobe_quadsphere_2k.jpg" is a 2048x2048 resolution starglobe image in the custom quadsphere UV layout.

The texture map named "starglobe_quadsphere_8k.jpg" is a 8192x8192 resolution starglobe image in the custom quadsphere UV layout.

The texure map named "starglobe_equirect_8k.jpg" is a 8192x4096 resolution starglobe image in the latitude/longitude equirectangular format.

Starglobe Texture Mapping

The Maya Starglobe Shelf tool uses a novel approach to texture mapping where an incandescent Lambert material is used in the realtime viewports and a mental ray native "mia_material_x_passes" shading network is used at render time.

Complete starglobe shading network

The benefit of this approach is the 2048x2048 texture map is linked to the realtime version of the Lambert shader and at 8192x8192 texture map is used at render time with the mental ray shader. The mental ray shading nodes have the additional feature of avoiding the common "blurry-line" artifact that existed when using older copies of mental ray prior to mental ray 3.14.

Light Linking

In order to avoid lighting issues on the starglobe mesh a custom light linking mode was used in the "mia_material_x_passes" shader. This should remove the need to manually stop the starglobe from interacting with the lights in your Maya scene.

light linking in mental ray

Starglobe Brightness Controls

The Domemaster3D v1.5 has another component in the starglobe shading network: a remapColor node that can be used to adjust the exposure of the render time starglobe texture map.

starglobe shading network

If the starglobe night sky background texture looks dark for your tastes, you can use the starglobe_remapColor node to brighten the texture map at render time.

To adjust the overall night sky image exposure, select the starglobe_remapColor node in the hypershade and expand the remapColor node's Input and Output Ranges section. The Output Max attribute is a direct multiplier for the image brightness. A value of 2.0 will make the image 200% brighter, a value of 4.0 will make the image 400% brighter, and a value of 0.5 will make the image 50% as bright.

starglobe_remapColor brightness adjustments

Starglobe + Maya 2016 Color Management

If you are rendering to PNG output in Maya 2016+ with Mental Ray you have to adjust the color management settings in the Maya Render Settings window to avoid visible color shifts in your renderings.

To render a PNG 8-bit per channel output in Maya 2016 you need to do the following steps:

  1. Start by opening the Render Settings window and switch to the common tab.

  2. Expand the Color Management section and enable the Apply Output Transform to Render checkbox. Then set the Output Transform options menu to "RAW".

Output Transform

  1. To avoid warnings about mental ray framebuffer conversions at render time we need to change the framebuffer from the default EXR style 16-bit half float format to use an 8-bit per channel PNG friendly option.

Switch to the Scene tab in the Render Settings window and then expand the Canvas section, and then expand the Primary Framebuffer section too.

Set the Data Type option to "RGBA (Byte) 4x8 Bit".

Framebuffer Settings

  1. If you want the real-time viewport windows in Maya to show the textures and materials with the same 8-bit per channel "PNG friendly" color management settings used in step 3 with mental ray, we need to set the viewport to use the "RAW" setting as well.

In the viewport window toolbar in maya 2016 there is a color management options menu. Select the RAW setting and the textures will look the same as they will appear when rendered in mental ray.

RAW Viewport Color Management

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