In this edition of our Home Run Pictures' "Inside the Production" page we will be describing in some detail the process we are going through to create a complex model of the Milky Way galaxy that is usable in fulldome animations... to fly around as well as into with a realistic representation of what it might look like... more will be added as we continue the work...
INTRODUCTION:
The Milky Way has always been difficult to visualize in a truly realistic fashion. The billions of stars , nebula, gas clouds and instellar dust represent an extremely complex task to create visually even with today's computer systems and software tools. Would too many compromises need to be taken. How far can we realistically go with our toolset and still have a visibly acceptable model for production... and in a fulldome capacity... we decided to find out...
PART ONE - OUR CHOSEN PATH TO ACCOMPLISH THIS:
After having successfully created a strong visualization of the Sun (see an earlier Inside The Production), we wondered if the Maya FluidEfx approach we used for that pipeline would work for creating a realistic looking model of the Milky Way. What we discovered during the process was that it was not the nebula and gas clouds that were the biggest hurdle, but representing the billions of stars as you viewed the galaxy from various angles and distances.
A single frame rendering of the finished Milky Way galaxy visualization. Click on image for a full-resolution HD1080 frame.
Most of the galaxy visualization imagery currently being seen relies on a viewer illusion of forced-perspective-scale. Stars fly by like in a Star Trek movie, closer stars many times larger than they would realistically appear. Audiences accept as well as expect this now as the way it would look even though the vast distances between stars is such that stars would all appear as points of light as you fly through the vast emptiness of interstellar space. Creating a galaxy visualization that both appeals to the audience's expectation, yet provides a truer view has proved difficult.
Screen-capture of our Milky Way visualization in the Autodesk Maya application interface.
As mentioned earlier, the task of representing the billions of stars in our galaxy became the most challenging aspect of the project. For obvious reasons, generating billions of stars would not be practical with anything less than a supercomputer... which we unfortunately don't have in our back room. So how to represent the many stars needed in a less computationally intensive fashion was devised.
Stars were generated in the arms of the galaxy model.
Representing stars as points that were relative in size to the screen view as opposed to the volume space they were contained in seemed like a place to start to create the look we felt was appropriatly a correct visualization. Fluid volumes where stars would be "emitted" were created and a multi-point approach to insure a random look was applied. Scripts to create a variation of size and color... size being the only way to represent varied brightness in CGI with the limitation of 8bit color... were written. And then a way to apply the characteristic look of each star yet allowing for the expected close/far perspective view by the viewer was added in.
Variation applied to the stars.
Star birthng areas were given their own fluid generated look.
The dark dust alleys. because of their distinct look, needed to be created separately with special fluid emitters. Using Maya's PaintEfx "branching" capability, typically used to create plants, a structure of branching was used to be the emitters for the dark gas and clouds making up the alleys and thus generate the fluids with the appropriate shape and textural look.
Dark dust alleys visualized in Maya's interface.
The dust, gases and nebula clouds were "placed" in an ordered fashion based on observations and then extended in a random way to fill out the entire disk.
Fluid and particle positions as displayed in the Maya interface prior to a final render .
Finally, the rendering process was tested and tweaked. Mental Ray was chosen as the rendering software and Maya's render passes were utilized with the goal of final compositing in Adobe AfterEffects. All frame passes were rendered in the EXR 32bit file format to further give the final compositing process more pixel inforrmation (color, gamma, exposure, etc.) to work with.
Some of the rendered layers--- Render pass for the dark alley layer.
Render pass for one of the glow layers.
Final composite with all layers.
Rendering was challenging even using a render farm with fast Xenon core, Apple Macintosh 12-processor servers, each with 32Gb of RAM. Frames were scheduled to allow each renderer initiated to multi-process and utilize the 24 threads available on each independant server. Render times varied and at times were as long as 2-3 hours per frame at a resolution of HD1080. Fulldome format renders at 4K are currently being tested.
That completes another Home Run Pictures' "Inside the Production." If you would like more information on the Milky Way model, just give me a call or drop me an email.
-TC
RENDERED SEQUENCE WILL BE POSTED AT A LATER TIME