In another edition of our Home Run Pictures' "Inside the Production" page we will be describing in some detail how we accomplished the production of the Sun sequences for a Buhl Planetarium show funded by the NASA Solar Dynamics Observatory (SDO) mission called "Solar Quest." We are very excited with the finished look of the show, especially the sequences featuring the Sun. Obviously since the show also features the incredible views of the Sun's surface that the SDO spacecraft has been capturing, we had to create an animated fulldome view that came close to that realism.
INTRODUCTION:
Upon acceptance of the task to handle the complete production of the ten minute show, we then began to determine the best path to accomplish a fairly realistic model of the Sun. At first we considered using a particle approach to drive the motion, possibly with Maya Fluids as textures as we had done in the past to create the exhaust for a rocket launch. But the Maya Fluids capability is quite extensive and it was determined to dive in and learn how to use Fluids themselves to drive all the motion as well.
Home Run Pictures' animator, Glen Johnson, spent five of the show's ten month production schedule creating the model of the Sun using our Maya software toolset. Applying Maya's Fluids capability and a lot of original MEL scripting, he was able to create an extremely realistic visualization of our closest star.
The surface and atmosphere of the Sun is an extremely complex environment. It was tdetermined that since we would usually be seeing only a portion of the surface, we could create a small subset of effects and just repeat them across the surface, offsetting the timings so the various copies would not look alike. Cache files were generated for the various fluid elements and saved in a directory on our netwrok so the Maya GUI or Mental Ray renderer could call these up quickly instead of generating them on the fly. The cache files alone for the model ended up taking close to a terabyte of disk space.
After some initial test renders we also discovered we needed to create a new fulldome camera shader for Mental Ray that allowed offsetting the camera's view and changing the angle of the field of view on the fly to achieve the various looks desired. At times we wanted to be looking at the full sphere of the Sun and at other times be traveling along the surface with the environment all around us in the 360 degree fulldome view. To avoid the problem of the Sun looking small through the extremely wide-angle fulldome lens the new camera allowed animating various camera parameters to create the "closeness" desired... you know, you can't fly too close to the Sun.
NUCLEAR FUSION:
Another sequence describing nuclear fusion inside the Sun was also required and seven-teen year old animator, Warren Casey, working at the studio as a summer job was tasked with this animation. Also using extensive MEL scripting to achieve the complexity the storyboards called for, thousands of hydrogen atoms with electrons orbiting were generated using repeating loops and sent into motion. At random times two would collide and fuse to create a helium atom releasing energy. For this simulation, particles were used. Many layers of particles and energy "washes" achieved the complex look as the camera pulls away and heads for the Sun's surface following the photons released in the fusion process.
CREATION OF THE SUN:
For the opening of the sequence where the narrator is describing how spinning, swirling gases, compacted by gravity eventually created our star, Maya Fluids were an easy choice. Fluids typically used to generate clouds were altered to achieve the needed look. As we dive into the primeval Sun, we eventually end up in the core where the fusion process is beginning. Then we zoom out to the surface where the visualization of the present Sun begins.
HOW IT WAS DONE:
To begin, the Sun's "surface" needed to be modeled. Unlike a planet, the Sun's surface is a constant flux of "boiling" granules, so typical texture mapping was not possible. The Sun sphere was divided into many small patches, each patch then contained a fluid "module" that was repeated across the surface. Activity across the surface was then generated by the three-dimensional quality of the fluid in each patch.
To create the Sun's atmosphere. over 700 fluid containers where positioned around the sphere similar to a geodesic dome. Fluid "flames" were then generated in each overlapping container to create the look of heat energy eminating from the surface.
Colonies of sunspots were also generated using a fluid container, placed manually around the sphere using SDO imagery to create a realistic pattern.
Arching loops created by the Sun's magnetic field were placed, several dozen variations were scattered randomly, each offset time-wise to create a variation in look.
All these various fluid elements were cached and saved to a directory on the studio's network... then readily available for quick playback in the Maya GUI and to be accessable to the render farm. Almost a terabyte in size, the studio's daily backup scripts had to be modified to avoid long network delays.
The various loops, prominences and flares visible on the Sun's surface had to be individually choreographed to look like the real events that the SDO spacecraft has photographed. Here a camera move through and under an arching event is shown.
Newly discovered twisters racing across the Sun's surface were mentioned in the script, their fluid containers flowing along the curve of the surface. Various "heads-up" displays helped the animator keep track of what was going on in the complex scene.
For the closing scene a massive coronal mass ejection or CME errupts from the surface and heads towards Earth foreshadowing the next sequence describing how the electro-magnetic field surrounding our planet protects us.
Various edits of camera moves were rendered to match up with the details in the script and narration. The overall complex model is a self contained module that can be used to create various future sequences simply by altering the camera's flight around and across the Sun's surface.
That does it for another Home Run Pictures' "Inside the Production." If you would like more information on the Sun model, just give me a call or drop me an email.s
Here's a link to a movie of the two sequences as a preview of the show that Buhl Planetarium will be distributing to planetariums later this year.
