The TurtleTank

TurtleTank Scene

Finally! My Turtletank project is finished. It’s taken many many nights of fidgeting, tweaking and solving but now it’s done and I’m pretty happy with the result. This project has been a first in many ways. It’s been the first time I ever had to spend more than a month on a single character, the first time I modeled a creature completely by my own design and the first serious sculpting project I ever did. Given these circumstances, I think the end result is pretty sweet.
It’s a fully rigged, animate-able, game ready End Boss model. I think it would be pretty cool fighting this guy in a first person shooter or something similar.

For more renders and information, please continue reading.

TurtleTank Viewpoints

The TurtleTank character was inspired by the excellent vehicle designs by Keith Thompson. Some of his drawings depict cyborg creatures re purposed as vehicles of war. I have always found this to be intriguing concept so I decided to give it a go myself. I went with a turtle because it lends itself well as some sort of tank, seeing as it already had the shell and retractable limbs.
I went through a couple of iterations during the concept phase and eventually chose for the tank to be unmanned. I figured the creature would be smart enough to attack only enemies and learn some basic strategic principles. Of course they would also have installed implants to take care of any unwanted behavioral anomalies.
The turtle might also be controlled remotely, giving commands by sending electric shocks to it’s brain. The creature would be in constant pain, due in no small part to the cybernetic modifications as well. This seems cruel but it turns out to fuel the creatures furiousness during combat, making the TurtleTank a force to be reckoned with.

Process

Modeling

The TurtleTank was modeled from scratch in 3d Studio Max 2011. This was a pretty straight forward process although I had a lot of things to figure out along the way. One of the most difficult things was to predict the best way to create the scales on the legs. I knew I wanted them to show up well in the silhouette but I wasn’t sure what the best approach was, especially keeping in mind that all of the scales needed some detailing in the sculpting phase. I settled on creating some simple geometric shapes placed along the front of the legs, scaled down towards the back. I hoped the transition from geometric scales to textured scales wouldn’t be too obvious but it worked out pretty nice eventually. The rest of the modeling wasn’t too difficult, the shell is completely rigid in animations so I didn’t have to worry too much about preparing the topology for animations. Only the base of the cannon and the places where the legs come together with the shell required some extra consideration but nothing too fancy.

TurtleTank Statsheet

When you glance at the stat sheet (image above), you may notice the tri-count of 29164. I realize this is pretty steep for an in-game 3d model but it was intended as a big character. He has a lot of separate elements and I wanted him to look good form all possible angles. There isn’t any geometry that doesn’t contribute to the silhouette so I think it’s still reasonable. I knew from the start that I wanted many details to be geometric rather than just textures. This makes a model a lot more interesting to me, especially the way it catches the light and how it adds to the contours. If the requirements for the model would’ve been more restrictive, I probably wouldn’t have modeled the separate scales on the shell, the impact craters and the little shield on the sides.

Rigging and Skinning

I chose to get this step out of the way as early in the process as possible. Experience has taught me that the geometry isn’t done until the rig is done. So often do you need to change the topology of the mesh to have the rig and skin work properly. I made a simple FK rig to make sure the limbs would cooperate nicely and to see if the topology would work. I didn’t have to change too many things but it’s an excellent way to check if you’re still on the right track.
Eventually I created IK links for the feet and made sure the head of the turtle could retract towards the shell. The most complicated part of the rig would be that of the cannon. I created a system that
allows you to animate a single bone to raise, lower and aim the cannon and have the support geometry at the front of the cannon move along with it correctly. Check out the vid below!

Sculpting

Once the rigging and UV mapping was done I knew I was happy with the topology of the mesh so I could start the sculpting process. I chose to use Mudbox as it has an easy to learn interface and some nice features I wished to take advantage of. The sculpting process ended up being a lot of work because in my enthusiasm I went a little bit overboard the smallest details. The next time around I might opt for doing the smallest details such as pores and small wrinkles in Photoshop instead. A custom heightmap converted to a normal map can give very quick and nice results. Anyhow, what’s done is done. Other than it being a lot of work, the sculpting was just plain fun. I don’t know why I never gave it a fair shot before.

One thing I realized while already deep into the sculpting process is the importance of evenly distributed edgeloops. Once you start subdividing your mesh it can be quite annoying if the amount of detail on your mesh is irregular. I might have saved a few millions of triangles if I fixed this beforehand. I learned that the other Sculpting tool: Zbrush offers the possibility to automatically take care of this for you. I was working in so Mudbox however so I didn’t have this option. Mudbox is a cool program to work with but once you get familiar with it, there are a lot of things that could be improved. My main gripe with it is the serious lack of proper tools to organize your scene. It also felt a little unstable and sluggish at times. The next time around I’ll probably give Zbrush a go.

Texturing

Now this part is always my favorite. You’re never really sure how your model is going to end up before the texturing part. I love seeing the model come to life this way. It’s also a very crucial part as it can really make or break the character. Before I could unleash myself in Photoshop I had to create the normal maps. Mudbox offers the possibility to generate these based on the difference between two subdivision levels. I played around with it before but I never really could get the results to look the way I wanted them to. Also, because my low poly model wasn’t exactly the same as the one I had loaded in Mudbox I chose to generate the normal maps in 3dsMax itself. For this to work I had to export the high detail meshes from Mudbox into 3dsMax. There’s no neat way to do this unfortunately, 3dsMax isn’t exactly good with handling ridiculous amounts of triangles. The only way I could get it to work is by optimizing the High detail meshes before getting them into 3dsMax. I did this using Mootools Polygon Cruncher. I was able to shave off about 50% of the trianglecount while still keeping all the details. This turned out to be enough to be able to work with it in 3dsMax. The normal maps I created were almost perfect. Barely any artifacts had to be fixed, I was very happy with the result.

Once all that was done, I was able to start with the funnest part. Creating shadow maps, using photographic material to composite a diffuse texture, tweaking specular values and whatever else is there. I love getting up close and personal with the smallest details and really bringing the character to life. I used a lot of photographic material from the awesome free online texture library: www.cgtextures.com.
One thing Mudbox really helped out great with was painting the base diffuse colors directly on to the model. There are other applications that allow you to do this such as Bodypaint, Photoshop and nowadays even 3dsMax as well, but none of them work as well as Mudbox. One of the coolest features it offers is the dry brush, this allows you to only paint on bulges, or crevices if you use the invert mode. This is great for painting dust in wrinkles or wear and tear on bulges.

Finishing up

The last steps are always the hardest. There were some difficult parts left to polish and fix, but thats all history now. I decided I wanted a cool environment to pose the character in, which you can see at the top of this post. This image cost me about two days or so to make. I also imported the character into the Unreal 3 engine. I’ll post a movie of that soon. All in all, the character turned out nice I think. It took a lot of work and effort but I also learned a lot. If you have any questions or comments, please don’t hesitate to contact me. I love to get in touch with anyone who’s interested in my work.

Wednesday, January 19th, 2011 Blog Tags: , ,

7 Comments to The TurtleTank

  • olivier says:

    a nice piece of art!

  • Jeroen Backx says:

    Thanks Olivier, glad you like it.

  • Jeroen Backx says:

    Hey Gerrit, my old pal from PL! Nice to hear from you here on my little interwebsite.
    I’m glad to hear you like it, coming from you, being the talented illustrator dude that you are, it means a lot!

  • Jeroen Backx says:

    hahah, hey Robin. Thanks man, appreciate it!
    I didn’t have facebook before (being the I dont like new things bah-humbug grumpy guy that I am) but thanks to you and Paul I had no choice. I was missing out on the facebook exposure of my model :)

  • Haha, I didn’t like Facebook before either. But it turned out to be THE place to meet new people and get cool assignments…so Facebook and I have become good friends :]

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    Greetings, dear visitor!

    I'm Jeroen, a 3d modeler and videogame artist from the Netherlands. I enjoy playing games but I looove to help create them. I'm pretty good at texturing, illustrating, concepting, working with game-engines, particle systems, physics simulations, rigging, skinning, animating and lots more but I'm most in my element when 3d modeling!

    I'm available for freelance work too!
    contact: jeroen [at] jeroenbackx.com