Project Green Dam: 3D Crab

As China watchers will know the term River Crab is often used as a Mainland code word for Internet censorship.

For the uninitiated, the Chinese word for "River Crab" (héxiè) is pronounced almost identically to the Chinese word for "Harmonious" (héxié). With only the last tone differentiating the two words in common speech. While the word use of the "Harmonious" is censored out online on a number of services, "River Crab" rarely is, so it makes a good substitute phrase.

The word "Harmonious" itself is often used by Beijing when it talks about crackdowns or censorship. For example, Beijing may say that it is "preserving social harmony" in a region after some local unrest. When what it actually means is that it's censoring the media to prevent the local ethnic people in one village from knowing that people from the same ethnic group in another village have gotten fed up with Han leaders seizing their farmland and selling it on to factory owners, and 10,000 of them have gone on the rampage. In case it inspires them to do the same.

Because of this use of the word River Crab, many images of Green Dam Girl have crabs in them. The most popular seems to be either as a logo on Green Dam Girl's cap or on their arm band.

ACB felt that the cap logo was the most appropriate, but they also wanted that there was scope to have an actual crab in future pictures, and they were not certain tat they liked the position of Green Dam Girl's head in the initial draft image.

This left three options

1) Draw several crabs
2) Draw a single crab and use the perspective feature in Photoshop to manipulate it into place
3) Get an actual crab that can be posed and added into the picture in any position

While option 3 might sound silly, ACB decided that it was probably the best option for providing a consistent crab regardless of how much the surrounding image changed, or where it was placed.

This left ACB with two further options. The first option was to a pose able model crab and Photoshop it into the picture using a digital camera, then use filters to make it appear to be a 2D poster paint crab. ACB didn't really give this much consideration as it was too time consuming for what amounts to a tiny part of the over all picture. Thus cam ACB's second option. Create a 3D model of a crab and render it into a 2D image. This option was the simplest and would provide the most constant result, so ACB chose it.

The crab itself was made in two parts, using two different computer packages. One to create the crab's body and to manage the lighting effects, and the other to make the claws. ACB had only ever made one previous attempt at creating an organic object in 3D (Organics are far less forgiving than furniture and so on) and was very out of practice with 3D, so getting the look right took little bit of extra effort.

First of all ACB made the crab's body and shell using a commercially available 3D rendering package. Both are formed from deformed primitives and were slotted together to form a complete unit. Next came the legs. Each leg is formed from 4 basic primitives. Two cylinders, a sphere and a cone. The cylinder primitives each form the top and bottom of the leg, respectively, with the sphere acting as the joint and the cone as the foot. ACB extruded a section of the cylinder making up the lower leg to give it a more realistic shape and then extruded and deformed the cone in order to form the cure of the foot. The eyes are cone and sphere primitives scaled and placed appropriately. You can't see it too well in the images given, but there is a nice bit of overlapping shell on the legs that sets them off nicely. From there is was limply a matter of stringing the parts of the leg together so they articulated properly, and so that when you moved one part of the leg the rest of it would follow appropriately rather than falling apart. One leg cloned several times and scaled a little equals a full set of eight crab legs.

Next ACB designed a pair of pincers for the crab. This was slightly more difficult due to their more complex shape which would require more advanced deforming and shaping tools. To this end ACB discarded the rendering tool and kicked things up a notch and used a professional 3D development package from an American company that they had on file from an earlier project.

To start with ACB experimented with deforming several primitives together but was not satisfied with the curvature
 that this gave, or the amount of manual correction that was needed in order to get a good effect.
Instead ACB decided to use a cutaway method to form each part of the pincer out of a deformed sphere primitive, with a third sphere primitive used to create the base of the claw.

A large sphere primitive was used for the outer part of the pincer. ACB deformed it to be long and thin, and then pretty much just sliced it in half, slicing more deeper into the primitive in the middle to create the curvature of the pinter. Some manual correction was required, but not much. To make the smaller part of the pincer ACB just flipped and resized the large part of the pincer. This gave a good effect So ACB left it at that.

The base of the pincer is just a sphere deformed into a rough lemon shape. ACB cut away the front of the sphere primitive, and part of the side. The pincers can then be positioned inside. The projection at the back of the base is just the end of the larger pincer showing through. ACB hadn't initially intended to do this, it was just a side effect of scaling the large pincer to the front of the claw, but it looks good. So ACB decided to keep it and make it into part of the arm.

Once all of the part were done ACB simple imported them all together and positioned them appropriately.

At this point the crab is still very simple. Primitive, you might say, though it's not a particularly funny joke, you will probably agree, and if you get it in less than 5 seconds you probably should go outside a bit more and locate some semblance of a social life. It needs properly coloring and maybe texture mapping, too. but it's fully pose able and positionable and ready to use to add to ACB's draft image.

As a 3D object the crab can be scaled small enough to use as the logo on Green Dam girl's cap or arm band. It can also be scaled larger to include in the Image. It can even be colored green and scaled large enough to replace Green Dam girl if required.

ACB will increase the level of detail on the crab as required once and then bring it out of the draft stage once it has been decided how big it needs to be and how it will be used. After all, there's no point in giving it a high resolution bump mapped shell if it's destined to be a cap logo the size, is there? but with this basic 3D construct ACB has the option of making things simple, or making them as complex as needed. ACB also has the option of animating the crab, too. Which is significantly simpler to do with a 3D object than with hand drawn frames.

tags: china  beijing  censorship  river  crab  green  dam  

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