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www.postmagazine.com 36 POST SEPTEMBER 2016 REALITY virtual Flamburis. "The important thing was to ask the right questions, practical ques- tions. What does the surface look like? What does it feel like? Why are there so many rocks? How big are the rocks?" In addition to information garnered from these discussions, Flamburis also ob- tained reference from image databases and from HiRISE, a camera on board the Mars Reconnaissance Orbiter. After close to a week of study, the team articulated a vision. Stina Flodstrom, a world builder and landscape/foliage artist, created gigapixel look boards from the plethora of reference material collect- ed. "Everyone spent a few days looking [at] and absorbing the imagery from the planet's surface so we knew what we were looking at, and then we started making assets," says Flamburis. Flamburis began the process using Pilgway's 3D-Coat voxel sculpting soft- ware and then textured the imagery using Allegorithmic's Substance Painter. "I am able to use a lot of smart materials for the geology I am forming with Substance Painter," he notes. "3D-Coat is fantastic for getting meta normals, but the details and feel, the PBR and the coloring were all done using smart materials I developed in Substance Painter." The artist team additionally used Nvidia's new GameWorks toolset to push performance levels and achieve the desired level of realism for the virtual-re- ality experience. The entire digital landscape is sur- rounded by global illumination, lit with a stationary light that is static and dynamic, casting a shadow map that may or may not remain in the final version of the ex- perience. At the end, there will be a good deal of post-processing work and some color grading that will be required. "Mars gets only 40 percent of the sunlight that we get on Earth, and we are still on the fence as to how dim we want this to be," says Flamburis. First, though, the artists needed to understand the geology of Mars. The soil is red due to an abundance of a powdery mineral called limonite, which is an iron oxide. As Flamburis explains, it's also the cause of the sky color: The dust permeates the atmosphere and scatters blue light, giving Mars its but- terscotch appearance. "In some places you could probably wipe the dust and sand off a rock and see a true color that is more gray or grayish blue," says Flamburis. "It's the total coat- ing of dust and iron oxide that give Mars its warm hue." Moreover, the planet comprises a plethora of basalt from volcanic activity, and a good deal of scoria, a bubbly matrix of volcanic and other rock. Also plentiful is silicate (sand), found in dunes as well as sandstone deposits. Lava caves are abundant, too, and there is widespread evidence of long-ago water flow. When creating the landscape surface, Flamburis integrated 75 different parame- ters that he can play with to get different looks. He also created a shader on the landscape that he made by hand. "At first, I tried a slope-based shader that would change composition by height, but that didn't work for Mars," he explains. "I just started with sand, then went with soil and broke down the sand and soil into two types. We have two styles of fractured sandstone embedded in it as well." The landscape shaders comprise: two soil shaders taken from photographic reference of the Martian surface (taken by the Curiosity rover), two sand shaders from remote-sensing HiVIEW images, two fracture shaders, a dust shader and various parameters. In a nutshell, there is a lot of iteration, back and forth, until things look and feel correct. In addition, a database of imagery provided height maps of craters, with infinite visibility down to 17 meters. "That was 5 gigs of height data that Justin [Sonnekalb] stitched together, brought into UE4 and used as the height offset for the Unreal Engine landscape," says Flamburis. "Then I started collecting the straight overhead shots of sand dune formations. It's a super-windy planet, but the wind does not have the same force as it does on Earth because there is very little atmospheric pressure. So, you get a lot of rippling, like on a beach, though on a massive scale." ROCKY SURFACE The Martian landscape is stark and minimalistic, what Flamburis calls "beau- tiful desolation," though it is dotted with rocks. And there is a science to creating and placing them in the VR application. Flamburis created a set of approximately 25 rocks of different geology based on the makeup of the planet. "I have folders of different geology, including scoria and basaltic rock. For the scoria, I created a rather large rock, broke that rock up into five pieces and then developed five or six additional rocks," he explains, noting that these assets are reusable. He retopologiz- es them in 3D-Coat and brings them into Autodesk's 3DS Max where he unwraps Rocks were placed throughout the landscape using the foliage system in the Unreal Engine. Above shows a wireframe view; below is a rendered view.