Modelign Next-Gen Characters: From Concept to Game
Posted March 29 4:52 PM by Kelly Murdock
On Friday, Kevin Lanning and Jerry O’Flaherty of Epic Games presented a session titled, “Modeling Next-Gen Characters from Concept to Game.” This excellent session demonstrated Epic’s pipeline for creating amazing realistic characters for their upcoming Gears of War title using 3ds Max and ZBrush.
Concepting
Jerry, the Art Director at Epic, began the presentation by speaking about the first phase of the pipeline—concepting. He stressed that one of the main goals of concept art is to present ideas that excite the team. It is also important that the designer buys into the concept art. Concept art should include lots of detailing and ortho views that the modeler can use.
Concept artists should follow three principles that will save a lot of headaches. 1. Think Ahead. By following this principle, the artist should consider potential problems and plan ways to overcome them. 2. Think Smart. Concept artists can save a lot of modeling time and make the team more efficient by reusing existing art assets. 3. Define the Style. The style of the characters really stems from the concept art. Reusing art assets like weapons and armor details will help the game characters to feel consistent across the game.
Modeling
Kevin, a Senior Character Modeler at Epic, then showed the modeling pipeline used at Epic to create two new characters for the upcoming Gears of War game. The modeling phase begins by breaking down the concept art into different segmented pieces. Each modeling type is then identified, including hard surfaces like armor and organic surfaces. Then a rough form of the character is created. During this stage, it is important to identify landmarks and to focus on the features, but the mesh is kept very simple. This base mesh is then set aside to be used later to create the low-poly character.
Through the process of “Kit Bashing,” new characters can be assembled from existing parts that are already modeled. Over time a complex library of body parts, armor and weapons have been created. Modifying these existing parts and assembling them into new characters has enabled Epic to improve their efficiency.
Using ZBrush
Once a character has been assembled and modeled to a medium resolution character, the organic portions of the character are pulled into ZBrush for high-res detailing. Before using ZBrush, some preparations are helpful. Kevin likes to enable the Keep Quads and Natural Seams options. He also tries to keep the topology of the mesh even. The UVs for each organic part are separated into a grid and exported from Max as an OBJ file. The OBJ files are then read into ZBrush as separate polygroups.
On each polygroup, ZBrush is used to sculpt in high-res details such as musculature, veins and sinew. It is important not to add or delete vertices while working in ZBrush. You may need to export the final model in chunks before importing it back into Max. To speed the optimization of the ZBrush OBJ files, Epic uses a piece of software called Polygon Cruncher, which can optimize detailed meshes up to 75% of their original size. It also offers batch optimization and protects borders. This utility can be found at www.mootools.com. Another helpful tool available at www.scriptspot.com is Blue’s Batch Importer. These utilities have reduced the time Kevin spent importing OBJ files back into Max from 1 day down to 10 minutes.
Once the high-res details from ZBrush are imported back into Max, the high-res model is completed and the focus shifts to the low-poly model. The high-res model is placed over the low-poly during the creation of the low-poly model. While modeling the low-poly model, frequently look at the character’s silhouette to make sure the character’s shape is maintained.
The character that Kevin used for the demo consisted of 24 million polygons, optimized to 6 million. The entire character was modeled in 3 1/2 weeks and a similar character was completed in 1 ½ weeks using kit bashing.
Unwrapping Workflow
Once high and low-poly versions of a character are complete, you can begin the texturing process. Epic uses Max’s Pelt mapping feature to do the base maps with two maps at 2048x2048. Deep UV is also used to add in texture details.
In preparation for generating maps, Kevin likes to zero out the meshes and use symmetry where possible by mirroring UVs. He also likes to render a map that color-codes the character objects by type. This is useful for the texture artists. Kevin also uses Max to generate a normal map that is delivered to the texture artist.
The texture artist will typically add many details directly to the normal map using Photoshop. Metal details can be pushed up using specular and specular power maps. Jerry commented that the eye actually perceives contrast more than color, which is why normal maps are so necessary for characters.
Conclusion
As next generation consoles appear with all their hardware power, the number of polygons on the screen isn’t going to be an issue. For future games, lighting will pose more of a problem than polygon count. With changing paradigms around next-gen character development, advances such as the ones found at Epic are going to be key.
Unite 2010
