SOFTIMAGE|XSI User Profile: SEGA
Ryu ga Gotoku KENZAN!—The Latest in the Popular Yakuza Series for PS3

Yoshiyuki Watanabe
Translated by: Alun Simpson

It is 1605, a few years after the tumultuous battle of Sekigahara. A man lives in Gion Iromachi, the amusement quarter of Kyoto that seems detached from the realities of the outside world.

He is a good fighter and he makes ends meet by hiring out his muscle around the neighborhood. His name is Kazumanosuke Kiryu, but he also goes by the alias Musashi Miyamoto.

One day, a small girl called Haruka, who seems innocent enough, appears before Kiryu.

"Please kill Musashi Miyamoto," she pleads. This girl's plaintive request is the trigger that gets Kiryu involved in whole lot of trouble...

Ryu ga Gotoku KENZAN! is a popular action game series, combining high-tension human drama with characters that are very realistic. So far over 1.7 million games have been sold.

This latest installment moves the era of the game from modern times to the Edo Period in 17th century Japan, adding extra spice to the background story.

Of course, the new game retains the moves for which the Yakuza series is well known, with fast-paced sword-fighting possible through simple operations, and the excitement of cutting down an enemy with a single blow.

The advanced processing power of PlayStation 3 supports high-quality graphics. The realism of the characters and the sparkling streets of Gion will make players feel as if they have stepped back in time to a different world. We decided to interview the people involved to see how this game was developed.

This was the first PS3 title for the NE Software Research and Development Division at Sega Corporation. Testing out how far they could push PS3's processing power was a process of trial and error.

With the previous title released only recently, the project had to be completed in a very short production period. But this series is a signature title for Sega, so the team was determined to achieve top-class character portrayal even though their time was limited. It was their mission to create animation of the best quality that would surpass anything that had gone before.

In their quest for quality, and battle against time, the weapon of choice for the game development team was XSI.

Staff at Sega's CS Development Management Division and NE Software Research and Development Division
		Misaka Kitamura: In charge of internal technical support for XSI Yuichi Higuchi: In charge of event scene management, from script production to rig setup Daisuke Tomoda: In charge of event character production Michio Shirako: Overall motion management, such as for characters, people and animals Eisuke Ito: Creation of Sega plug-ins such as for script C++ conversion and export Takashi Iwade: VFX related. Also in charge of coordinating this interview

Workflow for Creating Characters with 3D Scanning

3D scanning was used in the character production workflow for this project. The purpose was both to base the characters on real actors and to improve the work efficiency.

In the 3D scanning, data was recorded for the whole body and not just the face. Photographs were also shot to provide reference for the texture.

Digital data was recorded not only of famous actors but also of Sega staff, with data collected on 100 human bodies. The development staff themselves can be seen amongst the townspeople and courtesans who appear in the game!

In the 3D scan data for the 100 bodies, there are 300,000 polygons in each face area alone. The team efficiently modified this data into a form appropriate for the game as described below.

The team used a template, which is general-purpose face data of about 4200 polygons that is appropriate for games and where the envelope weight and UV information have already been set. They imported into this template the 3D scan target data consisting of 300,000 polygons.

The general-purpose face data was then roughly aligned with the target using XSI's modeling functions: the Tweak Component Tool and Proportional Modeling. The team then performed Shrink Wrap. They updated the shape of the general-purpose face model with a real person's face simply by selecting the option "Nearest surface (smoothed)". After this, the only work that remained was fine-tuning with the Tweak Component Tool.

Naturally, XSI's non destructive workflow means that even if the modeling is modified, the envelopes and UVs that are set in advance are carried over unchanged. This means that any retouching that does not involve modeling hardly takes any time. Using this process, the team improved its productivity and was able to produce approximately one face every day, including the texture. The bodies and clothes were created through the modeling work, without using the scanned data. At this stage, they discovered that GATOR envelope transfer on XSI 6's envelope editing function was very useful.

Daisuke Tomoda, who was in charge of the characters, had this to say: "Using 3D scan data for this project allowed us to maintain quality consistency and keep to our tight schedule. XSI 6 supports all the functions that we required in our workflow. I was particularly impressed by the accuracy of the XSI Shrink Wrap function and its one-shot operation."

Audio Analysis Facial Animation and Innovative Body Rigging

It is probably no exaggeration to say that this title was the first project to attempt to create animation with genuine Japanese facial characteristics on a next-generation console. The NE Software Research and Development Division put a lot of effort into facial animation.

The facial rigging varies depending on the video or game scene, but all the rigging was driven by Magical V Engine, audio analysis software that was developed by Sega. Based on an audio recording of a script read by a voice-over actor, V Engine blends about 20 to 30 facial expression patterns, taking into consideration the individual traits of the actor, to create natural animation. Even wrinkles on the face are created automatically. To further heighten the realism, elements such as the neck tendons and the Adam's apples of the characters are controlled automatically with the rig. The time saved through this automation can be spent improving quality in the fine-tuning stage.

A number of different methods are available for the rig setup of elements other than facial animation.
For body rigging, a rig setup was used where either FK or IK can be selected.

Although the movements of this IK were true IK, the direction constraints of FK Null bone were assigned to it, so it was actually a quasi-IK type. The team says that whether FK or IK is more efficient depends on the preferences of the animator or the type of work that they are doing. As such, they constructed a system that allowed animators to freely switch between IK and FK, making their work more comfortable.

To make the system compatible with fast action, a mechanism was incorporated in the shoulder up-vector so that it only rotated in the YZ axis, without following the X axis. Further, the team used a Sega add-on that absorbed the rotation.

A double bone structure is used for elbows and knees to resolve the collapsing issue caused by the bone shape.

A bone was added to the wrists to lessen the twisting, controlling the expression by stopping rotation beyond a certain point. Rigging was also used for finger movements that were based on the rotation of a control box. This rigging powered finger movements when hands grab something and during smooth hand motions.

In the animation environment, a reference model function was prepared that made workflows more efficient. For example, even after the animation was added and pose specifications were made based on the standard rigging described above, face models and body models could be freely substituted using the reference model. This allowed motion to be added efficiently to a large number of characters.

Yuichi Higuchi, who created this wide range of innovative rig setups, explained his work as follows: "The reference model concept is extremely useful when working under conditions where model modifications are frequently required. In this project, the elements that we substituted were bodies with FK Null bone and set envelopes. We used script base to perform the functions similar to Delta in XSI6, but in the future we would like to make full use of Delta Referencing."

In the game, a number of animal characters make an appearance during the explanation of "Tenkei" (Revelation), a special fighting technique. Rigging for non-human characters such as snakes, fish and oxen took only a little over an hour when using the XSI standard function.

Focus on Motion

In their animation work for the action scenes and events, the team used two methods: modifying motion capture data and using manual animation only.

Even when only counting motion capture, Sega used the largest amount of data in its history. 1300 motion types were recorded for the adventure story, while 600 motion types were recorded for the battles and heat moves. These recordings were so long they would last 27 days if played consecutively.

The attention to detail in the motion for the game action can be seen in the fact that the characters can move in eight different directions during play. A wide number of variations were required, such as turning around; low, high and middle stances that can move in harmony with the eight directions; and movements while holding weapons. It goes without saying that it would not be efficient to record motion capture for all these movements, or to add all the motions manually. As such, the team used the animation mixer to separate the upper and lower body movements and deal with the different motion variations. Through the skillful use of the mixer, even work that was difficult with capture or manual operations was made easy. The team created 92 derived motion types, for both the upper and lower sections, and they said that this also made subsequent control easier.

For the motion in fighting scenes with swords or other weapons, the captured information for weapon movements could not be used unchanged, so animation was added manually. A simple construction was used for the weapons, with only one bone. As a global constraint, the movement of the weapon was linked to the rotation of the wrist, and the sense of weight and impact was expressed in the global animation with the bone.

Michio Shirako explained, "We often read the f-curve to create our expressions. We modify the motions while checking the conditions in the global animation. The XSI f-curve editor is a tool that designers are used to, so it responds properly to our operations. We cannot imagine using anything other than XSI for motion work. This is true not just for the NE Software Research and Development Division, but also for workflows across the entire Sega Corporation."

In the motion work for event scenes, it was desirable for the designers to be able to properly check the movements even if they did not own the PS3 development equipment. To achieve this, Eisuke Ito, a programmer, prepared a preview environment in XSI for the real time shader based on DirectX, and a capture tool for checking the movements.

To enable previews and animation to be performed at the same time, Sega devised a display mode for blending DirectX displays and OpenGL displays with a special shader using Xgs (XSI Graphics Sequencer). This resulted in a dramatic improvement in productivity, because it enabled the easy selection and modification of rig controller types while checking the same image as the preview for the actual console.

Ito says that because this customization was based on a source code from SDK samples  , there were no difficulties in development.

Another advantage of XSI in terms of teamwork is the ease in setting up a collaborative environment.

For example, when XSI was installed on each user's machine at the NE Software Research and Development Division, setenve rewriting was performed, along with conversion to the 30-frame rate suitable for game production and the automatic selection of other preferences. Further, it was easy to update the changes because each user used a plug-in that imported DLL and VBS from the server as plug-ins. These useful tools created by Ito created a shared environment that was always updated to the latest version without the designers even being aware of it.

Breathing Life into Kusarigama and Kimonos

Kusarigama is a traditional Japanese weapon that is made up of a scythe with a chain at its end. In the event scenes, this weapon whips through the air like a living thing.

Misaka Kitamura prepared the following setup to control the movement of the Kusarigama.

She used cluster constraint on the curve path to portray the movement of the chain, which is notoriously difficult to reproduce. To control the shape of the path, two controllers were used. The first controller group moves the positions and roughly defines the shape and extension of the chain. Then, the second controller group performs fine tuning of the locations where the chain starts to bend and deflects due to the weight.

Customized parameters can also be used to restrict the total length to a certain percentage, which makes it easy to create the animation when the chain is thrown.

The deflection length when the chain is held in both hands or is rolled up can also be controlled with these parameters.

Two bones are included to facilitate control when the chain is held, controlling not only the length, but also the angle of the deflected chain and amount of jerking. These two bones are not directly animated; rather, a different bone is used to move the two bones, which simplifies operations while maintaining the ideal control. Bones are used here because the length of the bone does not change, making it appropriate for controlling the chain. Kitamura's setup allowed the animators to freely depict the jerking of the chain with a realistic sense of weight, and the wrapping up of the chain in a character's hands, simply by moving one bone.

200 items of bone data are converted for use in the final version of the scythe animation on the console.

In the radiant scene where the courtesan is dancing, the animation was created while paying close attention to the movement of her kimono.

First, cloth simulation was performed in the area suspended from her arms to calculate the movement of her clothes. This grid movement was transferred to a bone using a cluster constraint. In addition, control rigs were superimposed as layers to enable animators to edit the dynamic movement, and a setting was performed to enable the fine-tuning of quality.

In simple object control used in judging collisions with bodies, a method was used where envelopes were transferred with GATOR to items where the shape was aligned with Shrink Wrap. The realistic animation reproduces the special sense of weight of a kimono, which is converted to mixer clips, adjusted for timing and then output to the game.

Final thoughts

A great many people joined in this project to strengthen a team. These people have worked on Sega’s legendary fighting games both now and in the past. XSI enabled the team to push the limits in producing the best possible character and motion quality without making any compromises.

This game is not only enjoyable as a game, but is also impressive for the level of detail in its production.

We highly recommend that you experience its power for yourself.

Visit the Sega Corporation website
Visit the official Ryu ga Gotoku KENZAN! website

You can also read this story in Japanese on the Softimage Japan website.

(c) SEGA
PlayStation and PS3 are registered trademarks of Sony Computer Entertainment Inc.