Z4 Beta Testing By: Steve Warner

[Steve Warner]

Introduction

My name is Steve Warner. I'm the 3D Modeling Instructor at the Digital Animation and Visual Effects School and the author of three best-selling books on LightWave 3D. I began using ZBrush in 2003 with version 2.0 and went on to write the official ZPipeline Guide to LightWave for Pixologic.

Working with ZBrush 4 has been absolutely incredible. The tools and workflow enhancements in this new version have yielded one of the most powerful and easiest to use 3D applications on the market.

ZBrush is widely known for its outstanding organic modeling tools. But starting in ZBrush 3.0, a variety of hard-surface tools began appearing in the program. With the advent of ZBrush 4.0 (and features like Shadowbox and the new Clipping brushes), I wanted to see if ZBrush was truly up to the task of hard-surface modeling.

My primary 3D application is LightWave 3D. LightWave (and its spinoff Modo) have long been been recognized for their exceptional modeling tools. Hence, my expectations of what a program should offer for hard surface modeling work are quite high. The tools need to be fast, easy to use and produce great results. I'll be honest when I say I wasn't expecting much. But I was absolutely stunned by what I found. The hard surface tools in ZBrush 4 are astounding. They fit perfectly into the "sculpting" paradigm used throughout the program and make complex models a breeze to create.

Here is the result of roughly two weeks of work, done entirely in ZBrush 4:




Spetsnaz Tank Modeling Step-by-Step

Here is a rundown of the techniques used to build the Spetsnaz tank in ZBrush 4.0.














































Rendering Engine Improvements

Until ZBrush 4.0, users who wanted to render their work in ZBrush needed to oversize the canvas and use the AAHalf feature to get the effects of antialiasing. But with ZBrush 4.0, users can now render their objects and animations without changing the canvas size using the new "Best Preview Render" (BPR).

This new BPR rendering engine is amazing. BPR produces outstanding sub-pixel antialiasing with raytraced shadows, ambient occlusion (AO), sub-surface scattering (SSS), and support for ZBrush's Fiber material. Best of all, BPR can save out separate images for pure color, shadow, AO, SSS, ZDepth and Masking. This makes it easier than ever to post-process your renders and create finished illustrations.

Here are several additional renders of the Spetsnaz tank using the new Best Preview Renderer with raytraced shadows and ambient occlusion.




















Video Tutorials

Since I'd never done a hard surface object like this in ZBrush, I found myself developing new techniques to help create bevels, sharpen edges, fix alpha stretching and paint/sculpt on my flattened UVs. I created video tutorials for these (available in HD res), which you can view below.

Using Backtrack for Hard Surface Modeling
The Backtrack options (found in the Stroke menu when the Lazy Mouse feature is enabled) give you more control over your brush stroke. They can be incredibly useful when dealing with hard-surface models. In this video, I discuss how the Backtrack features work and how each setting can be used to help you achieve the results you want with your hard surface models.



Creating Hard Surface Bevels
Many hard-surface objects can be broken down into simple 2D shapes that have been extruded to give them 3D depth. Shadowbox makes it easy to create these shapes and give them 3D depth. But beveling the results (even with the Backtrack tools) can be a bit of work. In this video, I'll show you a quick technique for creating perfect "hard surface" bevels on your extruded objects.



Sharpening Soft Edges
As you work with the new Clipping brushes to create hard-surface shapes, you'll find that the geometry "bunches" up. One way to help redistribute the edges is to use the new Relax option in the Tool | Deformation menu. However relaxing your mesh tends to soften the edges. In this short video, I'll show you how to regain the sharp edges on your object.



Correcting Alpha Tile Stretching
In ZBrush 3.0, non-square alphas were squashed to fit within a perfectly square area. ZBrush 4.0 now has the ability to use non-square alphas, which opens the door for new brushs. (See my Rope and Chain brushes below). ZBrush 4.0 also has the ability to tile alphas. However when you tile an alpha, it will squash the results into a square area. In this video, I'll show you how to correct alpha stretching to maintan the proper aspect ratio.



UV Master Tricks
Most people know that UV Master can be used to create awesome UV maps in ZBrush. But did you know it can also be used to paint on your unwrapped geometry? Or that you can sculpt on the unwrapped geometry? In this two-part video, I show the principles you need to know to go beyond the basics with UV Master.

UV Master Tricks - Part 01



UV Master Tricks - Part 02



Using ZBrush MDDs in LightWave
ZBrush 4.0 uses native LightWave MDD (Motion Designer Data) files to "bake" its animations to the hard drive. Ironically, these MDD Files don't play well using the native MDD tools in LightWave. In this video, I'll show you how to work around this problem to get your MDD files working in LightWave.




Brushes
One of the joys of working with the ZBrush 4 Beta was testing the new features as they were developed. One of my favorite new features (which will likely get lost in the shadow of the Clipping Brushes, Shadowbox and Spotlight) is the support for non-square alphas. The ability to use non-square alphas opens a whole new set of options for detailing your objects. To test these out, I created two new brushes: Rope and Chain.





You can download these two new brushes here:

Click to Download the Chain and Rope Brushes

(The chain and rope brushes can also be downloaded via the attachment at the bottom of this post.)


Animation

Overview
Once I finished modeling the tank, I set out to animate it. Animation in ZBrush is accomplished via deformation layers. They work like Morphs in LightWave or Blendshapes in Maya. You create layers in ZBrush which store the location of each point at its start and end locations. Then you create a linear interpolation between the two by keyframing the transition on the Timeline. (ZBrush can store more than just point deformation. It can also store polypaint information, camera position, etc.)

It's important to note that the transition in ZBrush is linear and this can cause some unexpected results. For example, wheels (and other circular objects) can not be told to simply rotate around a central pivot. This means that you have to do a bit of work to get certain types of animation to look right. But it does work.

The MDD Format
LightWave users take note! ZBrush now uses LightWave's Motion Designer Data (MDD) file format to save object animation on the hard drive. This makes the animation pipeline between ZBrush and LightWave wide open. Anything you can animate in LightWave can be recorded to an MDD and brought into ZBrush. Imagine being able to run Cloth Dynamics on your character, storing the results as an MDD, and then bringing that into ZBrush. Sculpting dynamic folds and wrinkles just got a lot easier!

Here's a quick test showing a Cloth Dyamic animation created in LightWave and then applied with an MDD in ZBrush:



Animating Tread
There is an old trick to creating tank tread animation in LightWave using morphs. (Virtually anything you can do with morphs in LightWave, you can now do in ZBrush.) The trick basically involves moving each piece of the tread by one tread space. When animated, the tread will appear to move seamlessly. I did a quick proof of concept to see if this would work:



With a successful proof of concept, I moved on to creating the final animation. I began in ZBrush by consolodating my tread down to a single mesh. Your animation is recorded per Subtool, so it was important to make sure my tread was all on one Subtool. To do this, I used the Merge Visible option.

The resulting object consisted of roughly 60 pieces. (I didn't add tread to the top as it wasn't visible and would only bog down my model.) To ensure that I could quickly select each piece in the one Subtool, I went to the PolyGroup menu and chose the "AutoGroups" option. AutoGroups will assign a new group to each distinct (unweld) mesh in your Subtool.

Next, I duplicated the Subtool (so I could have a guide showing where my tread was and where it needed to go to). I used the Transparency option with Ghosting enabled to help see the second tread tool.

To set up an animation, you need to record the Subtool's deformation. To do this, I went to the Tool | Layers menu and created a new layer. This put the layer in Record mode - ready for deformation.

Next, I selected a single section of the tread by holding CTRL+Shift and clicking on it. This hid everything but the piece I wanted to work on. I then used the Transpose Move and Rotate tools to position the piece against the ghosted background object.

When I was finished, I showed the remaining tread pieces, selected the next one in line, and repeated the process.

When finished, I turned off the recording for the layer and dragged its slider. I could see the entire tread move forward by one tread piece. To get this to loop, I needed to record the animation to an MDD file.

I enabled the Timeline and positioned my camera. Then I clicked on the timeline to create an initial keyframe for the camera at Frame 0. I added another keyframe about half-way down the Timeline.

In order to animate in ZBrush, your camera needs at least two keyframes. The camera's keyframes determine the "recordable" portion of the timeline. And the length of the timeline itself can be adjusted (in seconds) in the Movie menu.

With the camera now set up, I went back to my tread deformation layer and clicked on it. The Timeline will only show the track for the current "element" (be it the camera or an object's layer). Clicking on the layer selected it as the active element. Next, I created a keyframe with the tread layer at 0% and another keyframe (where I set the camera's second keyframe) at 100%. Scrubbing the timeline, I could now see the animation.

I clicked the button in the Movie menu to store the MDD file and gave it a name. Then I CTRL+Shift+Clicked on area below the timeline to record the animation. This also stores the MDD file.

Once the MDD file was created, I disabled it in the Movie menu (so that it wouldn't be overwritten). I then went to the Layer menu and loaded the MDD file there.

To get the MDD file to show up, you need to place a keyframe for it on the Timeline. The location of the keyframe determines when the MDD file will start playing.

You can now control the MDD start time (via a keyframe on the timeline) and the MDD playback speed (in the Layer menu).

I repeated this process for the wheels and gears. The primary obstacle with these, however, was their circular nature. I couldn't just rotate the wheel. I had to rotate it in small increments by creating multiple Layers. And even then, I found that the deformation would cause "swelling" and "shrinking." So to offset this, I created "counterbalance" layers which compensated for the size change.

Another obstacle I encountered was the back gear. Since it "grabs" the tread and helps pull it along, it was crucial that it be timed properly with the tread animation. Unfortunately, however, the back gear is assymetrical. It could not be rotated 10 or 20 degrees and then looped. It would have to be rotated a full 360-degrees. And since wheel rotation is not easy with linear morphs, this became a major undertaking. I ended up animating the back gear separate from the rest of the tread and wheels. To get it to sync up to the tread, I used the MDD Playback Speed settings in the Layer menu.

I did several tests along the way before getting to the final. Here are two work-in-progress animations.

The first shows the finished tread animation.



The second shows the tank moving over a large terrain.



In order to get the tank (with its multiple subtools) to move along the ground, I simply animated the ground, leaving the tank in place, and then moved the camera to help hide the illusion.

Here is the final animation rendered with BPR and the metallic material I created.




Conclusion

It's been a privilege and honor to be a part of the beta team and to work alongside artists whom I have admired for years.

I want to thank Pixologic (and in particular Jaime, Paul and Ofer) for the tremendous opportunity they gave me, and for the chance to prove that ZBrush is no longer just a great organic modeling program. It is now one of the best hard surface modeling programs as well.

[chemkid]

cool tank! thanks for tips and brush-files!!

chem!

[Santis]

Awesome, thanks man!

[It's Alive!]

Steve those UV map tricks blew my mind. Free alphas, info on how to clean/re-crisp shadowbox created objects. Much appreciated

[Gareee]

I see a slight "hiccup" in the tank tread animation.. is it posible to clean that up completely?

Amazing work there, btw!

[campi]

Hey Steve. Great thread, very informative.

Question though:
In your UV Master Tutorial you are smoothing your flattened geo to paint on it. Don't you - just by the process of smoothing - change your UV borders slightly this way ? Even with crease active you would get different borders just by having more polys there. And once you step down to level 0 again Zbrush might average the vertex position so suddenly level 0 before smoothing and level 0 after are just a tiny bit different. Isn't that a problem ?

Thanks,
Jens

P.S.: Your Tank Step-by-Steps don't seem to be working. Or is that just general Releaseday Server crazyness.

[Gareee]

Probably server madness.. I viewed them wihout issue.

EDIT: Yep, the step by step images are busted here as well...

Where's mah damned email???

EDIT: I got's it!!!! Woo Hoo!

[Clintus Maximus]

Your step by step images are broken and i would REALLY REALLY LOVE to see them... beautiful work BTW

[dagoned]

A lot of valuable information here.. Thank you very much for sharing.. congrats on such a cool looking tank..

[Steve Warner]

** Apologies to all for the Step-by-Step images being down. I re-uploaded the images and everything should now be working. Please let me know if you continue to have trouble viewing them. **

@ chemkid: You're welcome!

@ It's Alive!: Awesome! Glad you found them helpful. :-)

@ Gareee: The hiccup is due to a bug in the MDD playback when it attempts to loop. I noticed this early on and reported it but in the last beta build, it was still happening. I thought it might be something in the way I set up the animation, so I exported the mdd and ran it on the geometry in LightWave and it played back fine. No hiccups. Same thing happens when importing MDDs from other programs. You'll get the hiccup even if your animation is flawless. I suspect this will be an easy thing to fix but was simply not a critical bug to catch before the release date.

@ campi: Thanks! Glad you found the info helpful. With regards to the UV issue, the answer is yes and no. This gets a little tricky, so hang in there:

1. If you don't crease the geometry, you will see the polygon borders shrink when you subdivide (as expected). This can cause a minor degree of stretching when painting, but it's not too extreme.

2. If you crease the geometry, it will maintain the polygon borders. I checked both the freshly unwrapped UVs and the creased-subdivided-then-return-to-Level-0 UVs in LightWave and there was no size change.

3. If you want to be absolutely certain that there is no stretching, don't use Crease. Simply turn off the Smooth option (SMT button) in the Geometry menu. This will simply subdivide the polygons in place without changing their shape.

Now, technically speaking, both Crease and Subdivide without the Smoothing option turned on will produce UVs that maintain their borders and don't lose their shape. However it appears that over the past few beta releases, something has changed which is causing the UVs to move slightly when you unflatten the mesh. It's not that the size of the geometry has changed. It's that the position of the UV chart has shifted by about 10 pixels. This wasn't happening when I recorded the video, but it's happening now. There are two ways to fix this.

Solution A: Rather than dropping to the lowest subdivision level and unflattening, simply stay at the highest subdivision level, then press Unflatten. It will ask if you want to transfer the results to your low resolution mesh. Just say no. It will effectively "cancel" the effect of the subdivision, leaving your original UV (prior to subdivision) in tact. You can then apply your texture map and everything will line up fine.

Solution B: Avoid the crease option and instead choose to turn off the Smooth subdivide option (SMT button). The smoothing is what's causing the mesh to shift. So even though creasing maintains the size of the UVs, it will not prevent them from shifting. (This is clearly a bug, so we're having to jump through hoops to work around it.) By turning off the "Smt" button, the geometry subdivides and remains in place. When you go to the lowest subdivision level and choose "Unflatten" the UV geometry will not shift and everything will line up just fine.

I'll put another video together showing this today or tomorrow and add it to my post.

@ Clintus Maximus: Thanks for your interest! I re-uploaded the Step-by-Step images. I can see them on this end. Try again on yours and let me know if you're still having trouble.

@ dragoned: Thanks so much!

[artstudio3]

a very useful thread, really!!!
thank you very much for sharing your knowledge with us ...

(forgive my poor english

[Airhendrix]

So let me get this right, you give us ONE week to model every little detail of this, and you get two? AND ZBrush 4 early? Man....

Anyway, great work as always Steve! Thank you so much for all the tutorials!

[Steve Warner]

@ artstudio3: You're welcome! I'm glad you found it useful!

@ Airhendrix: LOL! True, but that was in LightWave. Its hard-surface modeling tools are almost without equal.

[kennethdpedersen]

Steve, i am so giving you a back rub for this.... next time i am in town its on!

[ChillWill Graphix]

WOW, MAN!!! That's just AMAZING! Thank you for sharing the screen grabs and how to - I'm speechless and showing all of my friends what you have done. Unbelievable!!!


Mike