Stumbling Toward 'Awesomeness'

Perforce is a wily beast. A lot of companies use it, but I feel few outside of the IT department really have to deal with it much. As I work myself deeper and deeper into the damp hole that is asset validation, I have really been writing a lot of python to deal with certain issues; but always scripts that work from the outside.

Perforce has a system that allows you to write scripts that are run, server side, when any number of events are triggered. You can use many scripting languages, but I will only touch on Python.

Test Environment

To follow along here, you should set up a test environment. Perforce is freely downloadable, and free to use with 2 users. Of course you are going to need python, and p4python. So get your server running and add two users, a user and an administrator.

Your First Trigger

Let’s create the simplest python script. It will be a submit trigger that says ‘Hello World’ then passes or fails. If it passes, the item will be checked in to perforce, if it fails, it will not. exiting while returning a ’1′ is considered a fail, ’0′ a pass.

print 'Hello World!'
print 'No checkin for you!'
sys.exit(1)

Ok, so save this file as hello_trigger.py. Now go to a command line and enter ‘p4 triggers’ this will open a text document, edit that document to point to your trigger, like so (but point to the location of your script on disk):

Triggers:
	hello_trigger change-submit //depot/... "python X:/projects/2010/p4/hello_trigger.py"

Close/save the trigger TMP file, you should see ‘Triggers saved.’ echo’d at the prompt. Now, when we try to submit a file to the depot, we will get this:

So: awesome, you just DENIED your first check-in!

Connecting to Perforce from Inside a Trigger

So we are now denying check-ins, but let’s try to do some other things, let’s connect to perforce from inside a trigger.

from P4 import P4, P4Exception
 
p4 = P4()
 
try:
	#use whatever your admin l/p was
	#this isn't the safest, but it works at this beginner level
	p4.user = "admin"
	p4.password = "admin"
	p4.port = "1666"
	p4.connect()
	info = p4.run("info")
	print info
	sys.exit(1)
 
#this will return any errors
except P4Exception:
	for e in p4.errors: print e
	sys.exit(1)

So now when you try to submit a file to depot you will get this:

Passing Info to the Trigger

Now we are running triggers, accepting or denying checkins, but we really don’t know much about them. Let’s try to get enough info to where we could make a decision about whether or not we want the file to pass validation. Let’s make another python trigger, trigger_test.py, and let’s query something from the perforce server in the submit trigger. To do this we need to edit our trigger file like so:

Triggers:
	test change-submit //depot/... "python X:/projects/2010/p4/test_trigger.py %user% %changelist%"

This will pass the user and changelist number into the python script as an arg, the same way dragging/dropping passed args to python in my previous example. So let’s set that up, save the script from before as ‘test_trigger.py’ as shown above, and add the following:

import sys
from P4 import P4, P4Exception
 
p4 = P4()
describe = []
 
try:
	p4.user = "admin"
	p4.password = "admin"
	p4.port = "1666"
	p4.connect()
 
except P4Exception:
	for e in p4.errors: print e
	sys.exit(1)
 
print str(sys.argv)
describe = p4.run('describe',sys.argv[2])
print str(describe)
 
p4.disconnect()
sys.exit(1)

So, as you can see, it has returned the user and changelist number:

However, for this changelist to be useful, we query p4, asking the server to describe the changelist. This returns a lot of information about the changelist.

Where to Go From here

The few simple things shown here really give you the tools to do many more things. Here are some examples of triggers that can be  created with the know-how above:

• Deny check-ins of a certain filetype (like deny compiled source files/assets)
• Deny check-ins whose hash digest matches an existing file on the server
• Deny/allow a certain type of file check-in from a user in a certain group
• Email a lead any time a file in a certain folder is updated

Did you find this helpful? What creative triggers have you written?

click to enlarge

I have been researching the best options available for the D300 when it comes to quickly generating some lightprobes/panoramas. This of course means fisheye lenses. Currently, Sigma is the only company that makes a 180 degree circular fisheye. They come in two flavors, 8mm, and 4.5mm. The 8mm projects a full circle onto a full 35mm sensor (full frame), but on an APS-C sensor it is cropped. The 4.5mm however, throws a perfect circular image onto an APS-C sized sensor; I believe it is the only lens that does this.

The Pixels

You would think that the 4.5mm would be the way to go, I did until I took a look at both. It really comes down to the pixels. The width in pixels of the image thrown by the 4.5mm lens is roughly 2285px in diameter. So while you can shoot less, an entire panorama taking about 3 shots, it will come out as a <4k equirectangular. However, using the 8mm, you need 4 shots, plus one zenith (5 shots total) and it generates an 8k image.  While the 4.5mm does generate a 180 degree image across, as you can see it is very wasteful.

So why doesn’t the lens have full coverage in at least the short dimension? I think it’s because it’s a lens designed to fit Canon and Sigma cameras, not just Nikon. Canon sensors have a 1.6 crop factor and Sigma’s Foveon X3 has a 1.7 crop factor (13.8mm)! The coverage is so small because Nikon DX format has a 1.5 crop factor, the APS-C sensor is much larger than Canon or Sigma. The actual circle measures 12.3mm, even small for the Sigma, which makes me believe they future-proofed it for Four Thirds.

For an APS-C sensor like the D300, I would recommend the 8mm, unless you really need a full uncropped image. The 4.5mm, while being more expensive, also has an aperture of 2.8, compared to the 8mm (f/3.5)

I am not super constrained on time, if you are on set and shooting bracketed probes between takes or something, the 4.5mm will save you two shots (18 pictures) and this might be preferable. That said, it will only generate a 4k image in the end (which might be enough)

My friends Judd and Rich gave a talk on some of the Character Tech behind Uncharted 2. Here are the slides.

Size Matters.

Theaters presenting Avatar in 2D and Real3D, show a cropped 2.35:1 version, while 3D IMAX shows the original work at 1.85:1. You might not think that this matters, but you are losing a lot of the image in the crop. If you want to see it as the artists/director intended it looks like IMAX 3D is your only option.

Many, many people are having weird, buggy camera issues where you rotate a view and it snaps back to the pre-tumbled state (view does not update properly). There are posts all over, and Autodesk’s official response is “Consumer gaming videocards are not supported”. Really? That’s basically saying: All consumer video cards, gaming or not, are unsupported. I have had this issue on my laptop, which is surely not a ‘gaming’ machine. Autodesk says the ‘fix’ is to upgrade to an expensive pro-level video card. But what they maybe would tell you if they weren’t partnered with nVidia is: It’s an easy fix!

Find your Maya ENV file:

C:\Documents and Settings\Administrator\My Documents\maya\2009-x64\Maya.env

And add this environment variable to it:

MAYA_GEFORCE_SKIP_OVERLAY=1

Autodesk buried this information in their Maya 2009 Late Breaking Release Notes, and it fixes the issue completely! However, even on their official forum, Autodesk employees and moderators reply to these draw errors as follows:

Maya 2009 was tested with a finite number of graphics cards from ATI and Nvidia, with drivers from each vendor that provided the best performance, with the least amount of issues. (at the time of product launch).  A list of officially qualified hardware can be found here: http://www.autodesk.com/maya-hardware. Maya is not qualified/supported on consumer gaming cards.  Geforce card users can expect to have issues.  This is clearly stated in the official qualification charts mentioned above.

One of the Year’s Worst Films

Transformer’s 2 was rated by critics at around a 18% as shown on Rottentomatoes.com. This is possibly one of the lowest ratings for a hugely expensive summer blockbuster that I can remember. This makes the movie less well reviewed than Species III, Rambo IV, or even Rush Hour III.

But it has now shown to have had the second largest opening weekend of all time; raking in over 200 million dollars domestically and 390 million worldwide in it’s first 5 days. This is within 1% of the current reigning champion, Batman: The Dark Knight. Paramount’s national exit polling revealed that more than 90% of those surveyed said the new movie was as good as or better than the first film. About 67% of moviegoers polled said the film was “excellent,” an even better score than that generated by Paramount’s “Star Trek,” one of the year’s best-reviewed movies.

The critics unanimously told their readers this film was trash, and word of mouth brought the film to within one percent of the Dark Knight. Hell, Transformer’s 2 was shown on less screens and even grossed more dollars per screen than the Dark Knight.

So how did a movie that so many flocked to see; nearly toppling the current reigning all time champ, get reviewed so viciously?

As reviews started to roll in, I saw an interesting thing happen. Some reviews were posted before people had seen the film, trashing the Michael Bay, and not really referencing anything from the film itself. (These were not logged as ‘top critics’ on the site.) But it initiated a torrent of others jumping on the hatewagon; beating their chests and scampering in competition to come up with better, more scurrilous, insulting, and defamatory witticisms trashing the director and his film. It became what I termed a giant ‘snoodBall’. Each critic seemed to feel that in order to stand out above the rest, he had to give an even worse, more scathing review. This led to professional critics actually printing things I just find ridiculous:

“I hated every one of the 149 minutes. This is so bad it’s immoral. Michael Bay is a time-sucking vampire who will feast off your lost time.”
- Victoria Alexander

“Michael Bay has once again transformed garbage into something resembling a film..”
- Jeffrey M. Anderson

“Transformers: The Revenge of The Fallen is beyond bad, it carves out its own category of godawfulness.”
- Peter Travers (Rolling Stone)

Who can say they actively *hated* every minute of a movie? I was so surprised. I had seen an advance screening of the film here at ILM, and I knew it was no Citizen Kane, but it surely isn’t an 18%! It seems the reviewers are so disjointed from the public they serve. Apparently there comes a certain time when you simply cannot write a decent review for a movie that all your peers said was garbage, and that is when you are just adding to this gigantic hate machine and not really reviewing anything.

If the film would have been reviewed even a little more realistically (I mean come on, Terminator IV even has a 33%!) it would have easily had the 1% more to topple the Dark Knight; possibly becoming the worst reviewed #1 box office hit of all time.

I love this picture. It illustrates a few large problems with video games. One of which I have wanted to talk about for a while: Attachments of course. I am talking about the sword (yes, there is a sword, follow her arm to the left side of the image..)

Attaching props to a character that has to dynamically be seen from every angle through thousands of animations can be difficult. So difficult that people often give up. This was a promotional image for an upcoming Soul Calibur title, this goes to show you how difficult the issue is. Or maybe no one even noticed she was holding a sword. So let’s look at a promotional image from another game:

Why does it happen?

Well, props are often interchangeable. Many different props are supposed to attach to the same location throughout the game. This is generally done by marking up the prop and the skeleton with two attachment points that snap to one another.

In this case you often have one guy modeling the prop, one guy placing the skeleton, and one guy creating the animation. All these people have to work together.

How can we avoid these problems?

This problem is most noticeable at the end of the line: you would really only see it in the game. But this is one of the few times you will hear me say that checking it ‘in the engine’ is a bad idea. It’s hard enough to get animators to check their animation, much less test all the props in a ‘prop test level’ of sorts.

I feel problems like this mainly show up in magazines and final games because you are leaving it up to QA and other people who don’t know what to look for. There was a saying I developed while at Crytek when trying to impart some things on new tech art hires: “Does QA know what your alien should deform like? And should they?” The answer is no, and it also goes for the things above. Who knows how robotnik grips his bow.. you do, the guy rigging the character.

So in this case I am all for systems that allow animators to instantly load any common weapons and props from the game directly onto the character in the DCC app. You need a system that allows animators to be able to attach any commonly used prop at any time during any animation (especially movement anims)

Order of operations

Generally I would say:

1. The animator picks a pivot point on the character. They will be animating/pivoting around this.
2. The tech artist ‘marks’ up the skeleton with the appropriate offset transform.
3. The modeler ‘marks’ his prop and tests it (iteratively) on one character
4. The tech artist adds the marked up prop (or low res version) to a special file that is streamlined for automagically merging in items. Then adds a UI element that allows the animator to select the prop from a drop down and see it imported and attached to the character.

Complications

I can remember many heated discussions about problems like this. The more people that really care about hte final product, and the more detailed or realistic games and characters get, the more things like this will be scrutinized.

This is more of a simple problem that just takes care and diligence, whereas things like multiple hand positions and hand poses are a little more difficult. Or attachments that attach via a physics constraint in the engine. There are also other, much more difficult issues in this realm, like exact positioning of AI characters for interacting with each other and the environment, which is another tough ‘snap me into the right place’ problem dealing with marking up a character and an item in the world to interact with.

I ran out and got Street Fighter 4 (SF4) just like everyone else. Street Fighter was ‘the game’ you had to beat all the kids in the neighborhood at for an entire generation (sadly replaced by PES), and I have very fond memories of playing it.

SF4 is the first 3D game in the series created by Capcom, in the past, Street Fighter EX was developed by Arika, a company formed by one of the creators of the original game as well as many other Capcom employees. Even though porting the franchise to 3D was largely considered a complete and utter failure, they decided to give it another go, this time ‘officially’.

Strengths and Weaknesses

As artistic mediums, 2D and 3D are very different. 3D art is perspective correct, it is clean, sterile and perfect. It is much simpler to do rotations and transformations of rigid objects in 3D, this is why Disney started doing vehicles as cel shaded 3D objects in their later films. However, it is very difficult to add character to 3D geometry. As an example, think of Cruella Deville’s car from 101 Dalmatians, it has character. (When it’s not overly-rotoscoped from a real life model)

2D lends itself to organic shapes, which can be gestural, and are ‘rendered’ by a human being; so they’re never perfect. 3D is great for vehicles and space ships, anything that generally lacks character. 3D is also the only way you are going to get a photo-real gaming experience. For instance; when we were making Crysis, we knew this was the only way, there was never a question of which medium to use.

When I go on my ’2D/3D rant’, I usually hearken back to something I love, so let’s take a look at the transition of an older game from 2D to 3D: the Monkey Island Series.

Many years ago developers felt that in order to compete, they had to ship games with the latest 3D technology. This is really unfortunate, and leads to them choosing to sometimes develop an ‘ok’ 3D game over a ‘beautiful’ 2D game. I believe in Curse of Monkey Island (last 2D title in the series (so far)), in the options menu there was an option to “Enable 3D acceleration”, upon clicking it, the words “We were only kidding” and other phrases pop up next to the radio button. The developers were already feeling the pressure to release a 3D game.

2D games are still profitable, just look at Xbox Live, where 2D games like Castle Crashers have been some of the top selling titles this year.

Lastly, lets not forget that 3D games are actually cheaper, or have been, historically. However, maybe not with some current-gen titles; where garbage cans have 4k texture maps and take two weeks to sculpt in Z Brush. But animation is definitely easier than it ever was. Of course the other side of that argument is that you can now have 6k animations in a game.

Street Fighter 4 Is A Three Dimensional ’2D’ Game

Before going on, it’s important to note that in SF4, the characters still move on a 2D plane as they always have. It’s actually nearly identical to all the other games in the series as far as design.

As always, you are pitting your guy up against someone else, and both of your characters are the focal point, they are the only interactive things in a game which centers around them. This is a series that has always been about character, and has always been 2D with great hand drawn art. Remember: Capcom offered fans a 3D game and they did not want it.

So, SF4 is a game that takes place in 2D space and focuses on only two characters at any given time. This is great news, it means you can really focus on the characters, moreso than almost any other game genre.

The Constraints of a 3D Character Art Style

3D characters are driven by ‘joints’ or ‘bones’. Each joint has some 3D points rigidly ‘glued’ to it, because of this, 3D characters, especially in games, look rigid; like action figures. In my opinion SF4 characters feel like lifeless marionettes. In a 2D game, you can quickly and easily draw any form you want. The more you want to alter the ‘form’ a 3D character, the more joints it takes, and the more complex the ‘rig’ that drives the character. Also, on consoles, the number of joints you can use are limited. This is easily distinguished when comparing 2D and 3D art:

Notice how the 3D characters look lifeless? They don’t have to, it’s just more difficult. Whereas before, adding a cool facial expression meant simply drawing it by hand. Now it means sculpting a 3D shape: by hand. It’s tedious and difficult. Also, notice how in 3D Chun Li’s cloth is ‘clipping’ into her leg, or Cammy’s wrist guard is ‘clipping’ into her bicep. 3D is much more difficult to get right, because you are messing with sculptures, not drawings. You could also say the foreshortening on Chun Li’s arm in 2D looks weird; there are trade-offs, but in a 2D pipeline is also much easier to alter character proportions and fix things.

There are entire web pages dedicated to the weird faces of SF4 characters. It seems one of the easiest ways to make a character look in ‘pain’ was to translate the eyeballs out of the head: it looks ridiculous when compared to the hand-drawn hit reactions:

Whereas before you had one guy drawing pictures of a character in motion (maybe someone to color), now it takes a team to do the same job. You often have a modeler, technical artist, and animator, then hopefully a graphics engineer for rendering. That’s a lot of people to do something one person used to handle, and it introduces not only beaurocracy, but a complicated set of choreographed events that culminate in the final product.

This is a Capcom press image of Chun Li and it highlights my point exactly. It is harder and much more complicated to sculpt a form than draw it. Not to mention sculpt it over time, using complicated mathematical tools to manipulate geometry. However, it’s not an impossible task, and to think that this is ‘ok’ enough to release as a press image for an upcoming AAA game is crazy.

It’s not just deformation and posing, but animation in general. There is a lot of laziness associated with 3D animation. Let me be more precise: it is easier to ‘create’ animation because the computer interpolates between poses for you. As an animator, you have to work much harder to not fall into this ‘gap’ of letting the machine do the work for you. Playing SF4 you will see sweeps, hurricane kicks, and various other animations that just rotate the entire character as if on a pin. They also share and recycle the same animations on different characters, this was not possible in 2D.

One thing I find interesting is that, though the new game is 3D, it really has no motionblur. The 2D games had Chuck-Jonesesque motionblur drawn into the frames to add a quickness and ‘snap’, but it also adds an organic quality that is lacking in SF4.

EDIT: Having now logged a lot more time playing, there is indeed a weird kind of motion blur, it’s barely noticeable at all and looks almost hand painted/added.

Another odd thing, I can spot mocap when I see it, and I think the technique was used on some of the background characters, like the children playing under the bridge. The motion is so stellar that it puts the main characters to shame. That’s kind of sad. Though, all new characters introduced on the console seem to have much better animation, so maybe this is something Capcom have worked on more.

So Why Make A 3D Street Fighter?

If you aren’t going to make a game where characters can move through 3D space (no Z depth), why use a 3D art style, especially when it is harder to create expressive characters?

I will offer some reasons to ‘reboot’ the Street Fighter franchise as a 3D fighter:

• Finally use collision detection to not have characters clip into one another as they always have
• Use physics to blend ragdoll into hit reactions, also for hit detection and impulse generation; maybe allow a punch to actually connect with the opponent (gasp)
• Use jiggly bones for something other than breasts/fat, things like muscles and flesh to add a sense of weight
• Employ a cloth solver, c’mon this is a character showcase; if NBA games can solve cloth for all on court characters, you can surely do nice cloth for two.
• Markup the skeletons to allow for ‘grab points’ so that throw hand positions vary on char size and are unique
• Attach proxies to the feet and have them interact with trash/grass on the ground in levels
• Use IK in a meaningful way to always look at your opponent, dynamically grab him in mid animation, always keep feet on slightly uneven ground, or hit diff size opponents (or parameterize the anims to do these)
• Play different animations on different body parts at different times, you are not locked into the same full body on a frame like 2D
• For instance: se ‘offset animations’ blended into the main animation set to dynamically create the health of the character, or heck, change the facial animation to make them look more tired/hurt.
• Shaders! In 3D you can use many complex shaders, to render ‘photorealistic or non-photorealistic images (like cartoons)
• You can also write shaders to do things like calculate/add motionblur!

Unfortunately: Capcom did none of these. Sure, a few of the above would have been somewhat revolutionary for the franchise, but as it stands, 3D characters add nothing to SF4, I believe they actually degrade the quality of the visuals.

EDIT: After playing more I have noticed that they are using IK (look IK) on just the head bone, shorter characters look up when a large character jumps in front of them.

Ladislav Kavan is presenting a paper entitled ‘Automatic Linearization of Nonlinear Skinning‘ at the 2009 Symposium on Interactive 3D Graphics and Games on skinning arbitrary deformations! Run over to his site and check it out. In my opinion, this is the holy grail of sorts. You rig any way you want, have complex deformation that can only solve at 1 frame an hour? No problem, bake a range of motion to pose-driven, procedurally placed, animated, and weighted joints. People, Kavan included, have been presenting papers in the past with systems somewhat like this, but nothing this polished and final. I have talked to him about this stuff in the past and it’s great to see the stuff he’s been working on and that it really is all I had hoped for!

This will change things.

No longer working for Crytek, maybe I can comment on some industry related things without worrying that my opinions could be misconstrewn as those of my former employer.

EuroGamer visited Quantic Dream this week, the studio working on the game ‘Heavy Rain’, who’s founder, de Fondaumière, arrogantly proclaimed that there was ‘no longer an uncanny valley‘, and that there are ‘very, very few‘ real artists in the video game industry. (A real class act, no?)

So their article starts with “We can’t tell you how Heavy Rain looks, sounds or plays…”, which I find kind of ridiculous seeing as how the studio’s only real claim to fame right now is the hype of it’s co-founder who casually claims they have accomplished one of the most amazing visual feats in the history of computer graphics (in real-time no less!).

Across the world there are thousands of outstanding artists chasing this same dream, from Final Fantasy, to Polar Express and Beowulf; people have tried to cross the ‘uncanny valley’ for years, and are getting closer every day. At Christmas you will be treated to what is probably one of the closest attempts yet. (Digital Domain’s work in Benjamin Button)

Not really having any videos to back up the hyperbole, they gave the EuroGamer staff a laundry list of statistics about their production.

I have yet to see anything stunning to back up the talk, 8 months after making his statement about crossing the uncanny valley, they released this video, which was just not even close, to be frank.

It looks like they aren’t using performance capture. Without markers on the face this means they have to solve the facial animation from elsewhere, usually a seated actress who pretends to be saying lines that were said in the other full body capture session. There’s a reason why studios like Imageworks don’t do this, it’s hard to sync the two performances together. If they have accomplished what other’s have not, with much less hardware/technology, it means they have some of the best artists/animators out there, and I say hats off to them.

But with every image they do release, and every arrogant statement, it is digging the hole deeper. The sad thing is they could release of of the greatest interactive experiences yet, but their main claim is the most realistic cg humans yet to be seen, and if they fail at this, it will overshadow everything.

At least they know how their fellow ps3 devs over at Guerilla must have been feeling for a few years now.

I am now living in San Francisco! My last day at Crytek was October 31st, and it was pretty difficult for me as it is one of the best companies I have ever worked for. I have so much respect for all the guys that helped constantly push the envelope and make Crytek the renowned world player that it is today.

I started last week as a Creature TD at Industrial Light + Magic; about the only thing that could wrench me away from Frankfurt. I have always been so interested in creatures and anatomy, and, from a young age, considered ILM the best of the best when it came to these. I feel very lucky to be able to join another great team of people, and not only that, but learn so much from them on a daily basis.

I don’t know what effect that will have on this blog. I can continue to comment on games stuff, but, being a large company ILM is a lot more restrictive in what I can do (even in my spare time!) versus Crytek. Not to mention I will be very, very busy the next few months.

I saw this presentation about a year ago, talking about the pipeline Epic uses on their games. Maybe some interesting stuff for others here. The images are larger, you can right click -> view image to see a larger version.

45 days or more to create a single character… wow.

They don’t use polycruncher to generate LODs, they do this by hand. They just use it to import the mesh into max in a usable form from mudbox/zbrush.

They don’t care so much about intersecting meshes when making the high res, as it’s just used to derive the nMap, not RP a statue or anything.

They said they only use DeepUV for it’s ‘relax’ feature. They make extensive use of the 3DS Max ‘render to texture’ as well.

Their UT07 characters are highly customizable. Individual armor parts can be added or removed, or even modded. Their UV maps are broken down into set sections that can be generated on the fly. So there are still 2×2048 maps but all the maps can be very different. This is something I have also seen in WoW and other games.

They mentioned many times how they use COLLADA heavily to go between DCC apps.

They share a lot of common components accross characters

I have seen some of the other material in the SIGGRAPH Image Metrics presskit posted online [Emily Tech Demo] ['How To' video], but not the video that shows the making of the Emily tech demo. So here’s that as well:

At the end, there’s a quote from Peter Plantec about how Image Metrics has finally ‘crossed the uncanny valley’, but seriously, am I the only one who thinks the shading is a bit off, and besides that, what’s the point of laying a duplicate of face directly on top of one in a video? Shouldn’t they have shown her talking in a different setting? Maybe showed how they can remap the animation to a different face? There is no reason not to just use the original plate in this example.

EDIT: I would like this to be a ‘living document’ of sorts, please send me terms and definitions and feel free to correct mine!

Whether you’re a technical artist in games or film, when trying to create realistic scenes and characters, the more you know about how light works and interacts with surfaces in the world, and the more reference of this you have, the better you can explain why you think an image looks ‘off’.

You are an technical artist. You need to be able to communicate with technical people using terminology they understand. We often act as bridges between artists and programmers, it is very important for us to be able to communicate with both appropriately.

Light transport is basically the big nerd word for how light gets from one place to another, and scattering is usually how surfaces interact with light.

You can see something in a rendered image and know it looks ‘wrong’, but it’s important to understand why it looks wrong, and be able to accurately explain to the programming team how it can be improved upon. To do this you should be able to:

1) present examples of photographic reference

2) communicate with general terms that others can understand

General Terminology

The following terms come from optics, photography and art, you should not only understand these, but use them when explaining why something does not look ‘right’. I will give both the technical term and my shortest approximation:

Specular Reflection – sharp reflection of light from a surface that somewhat retains an image (eg. glossy)
Diffuse Reflection – uneven reflection of light from a surface that does not retain the image (eg. matte)
Diffuse Interreflection – light reflected off other diffuse objects
Diffraction – what happens to a wave when it hits an obstacle, this could be an ocean wave hitting a jetty, or a light wave hitting a grate.
Depth od Field – the area in an image that is in focus
Bokeh – the blurry background in a photo that is not in focus
Chromatic Abberation – the colored fringes around an object or light refracted through an object, it’s because certain wavelengths of light get bent ‘out-of-sync’, i usually think of it as an old projector or monitor that is misaligned; that’s what this effect looks like.
Caustics – light rays shined through a refractive object onto another surface
Angle of Incidence – this is actually the angle something is off from ‘straight on’, but we mainly use this when talking about shaders or things that are view-dependent. If you were to draw a line from your eyes to a surface, the angle between this and it’s ‘normal’ is the ‘angle of incidence’. Car paint whose color changes as you walk around it is a good example: it changes based on the angle you see it. Just remember, your head doesn’t have to move, the object can move, changing the angle between your sightline and the surface.
Refractive Index (Refraction) – how light’s direction changes when moving through an object. the refractive index of water is 1.3, glass has a higher refractive index at 1.4 to 1.6
Reflection – the changing of direction of light, usually casting light onto something, like the camera or our eyes
Glossiness – the ability of a surface to reflect specular light, the smaller amount of specular light reflected usually makes something look ‘glossier’
Ray – think of a ray as a single beam of light; a single particle. This particle moves in a ‘ray’, when we talk about ‘ray tracing’ we mean tracing the path of a ray from a light source through a scene.
Fresnel – pronounced ‘fre-nel’, it is the amount of view dependent reflectance on a surface. a great example is rim lighting, but fresnel effects are used to fake a fuzzy look, x-ray effects, light reflected off the ocean, etc.
Aerial Perspective – this is how things get lighter as they recede into the distance, the more air, or ‘atmosphere’ between you and the object (mountain, building, etc) the lighter it is visually. I grew up in Florida, we don’t have much of this effect at all due to elevation and clear skies.
High Dynamic Range Imaging (HDR) – this just means you are dealing with more light data than a normal image. An HDR image has a larger range of light information stored in it. With today’s prosumer DSLR’s it is possible to capture 14bit images that theoretically contain ’13-14 stops’ of linear data. A digital example could be the sky in the game Crysis, it was a dynamic HDR skydome, this meant that the game engine was computing more light than could be displayed on the monitor. In these situations, this data is tonemapped to create visually interesting lighting situations.
Tone Mapping – this is how you can ‘map’ one set of colors onto another, in games it generally means ‘mapping’ high dynamic range data into a limited dynamic range, like a tv set or monitor. This can be done by ‘blooming’ areas that are overbright and other various techniques.\
Bloom – ‘bloom’ is the gradient fringe you see around really brightly lit areas in an image, like a window to a bright sky seen from inside a dark room.
Albedo – the extent to which a surface diffusely reflects light from the sun.
Afterimage Effect – this belongs to a groups of effects I call ‘accumulation-buffer effects’. the after-image effect visually ‘burns-in’ the brightest parts of a previous image, simulating the effect our eyes have when adjusting to bright light.
Deferred Rendering – this is a type of rendering where you render parts of the image to framebuffer storage instead of rendering directly to the pixel-output. Deferred rendering generally allows you ot use many more light sources in real-time rendering. One problem deferred rendering has is that it cannot properly deal with transparent items.
Scanline Rendering – Scanline rendering is a very old technique where you render one line of pixels after another. Pixar’s Renderman is a scanline renderer, but also the NintendoDS uses scanline rendering.
Skylight (or Diffuse Sky Radiation) – this is the fancy term for light that comes not from the sun, but is reflected from the sky. It is what makes sunlight on earth inherently blue, or orange.
Scattering (including Sub-Surface Scattering) – this just means how particles are ‘scattered’ or deviate from an original path. In sub-surface-scattering, light enters an object, and bounces around inside (sub-surface). This leads to things like the orange/red color of your ear when there it a light behind it.
Participating Media – the way a group of particles can effect light transport through their volume, not only reflect or refract light, but scatter it. Things like glass, water, fog and smoke are all participating media.
Ambient Occlusion – this is a shading effect where occluded areas are shaded, much like access maps of the old days, cracks and areas where light would have a hard time ‘getting into’ are shaded.
Screen Space Ambient Occlusion – a rendering technique that fakes ambient occlusion with some z-buffer trickery. By taking the distances between objects in a scene, the algorithm generates approximated occlusion data in real time. (first used on Crysis!)
Global Illumination – a way of rendering where you measure light bounces, as the light bounces around a scene, this generates indirect lighting. An example of this would be how a red ball next to a white wall will cast red light onto the wall.
Z-Buffer – is where 3d depth information is stored in a 2d image. A 16bit z-buffer has 65536 levels of depth, while an 8 bit has 256. Items on the same level cause flickering or ‘z-fighting’.
Z-Fighting – this occurs when polygons have similar z-buffer values, it is a term you should know when dealing with virtual cameras, not real ones. You can see this flickering when you create 2 co-planer planes on top of each other in a 3d app. To eliminate z-fighting you can use 24 or 32bit zbuffers.
Frustrum – everything in the camera’s field of view; generally the entire volume that the camera can see.
Environment Reflection – the way of faking a reflection by applying an image to a surface, this can be a spherical map, cube map, etc. Some environmental reflections (cubemaps) can be generated at rutime as you move an object around. (most notably in racing games)
Cubic Environment Mapping – a way of generating an environmental reflection map with six sides that are mapped onto a cube, recreating the reflection of the environment around an object.
SkyBox – creating a ‘sky’ in a virtual scene by enclosing the entire scene in a large box with images on 5 sides.

Here are some example sentences:

Artist: This place here where the light shines on the surface is too small, it makes my object look too wet.
Technical Artist: The surface is too glossy, as a result, the area of specular reflection where you see the light is very small.

Artist: Like in the photos we took, things in the distance should be lighter, in the engine can we make things lighter as they get farther away?
Technical Artist: As things recede into the distance, aerial perspective causes them to become lighter, to acheive this we should increase the environment fog slightly.

Taking Photographic Reference

I feel every technical artist who assesses visual output should own a proper Digital Single Lens Reflex camera (DSLR), no matter what quality or how old. This will force you to understand and work with many of the terms above. The artist in you will want to take good pictures, and this is much more than good composition, you are essentially recording light. You will need to learn a lot to be able to properly meter and record light in different situations. Because it’s digital, you will be able to iterate and learn fast, recognizing cause and effect relationships the same way we do with the realtime feedback of scripting languages in 3d apps.

I grew up in the US though I now live in Europe. This is just a short post about something that I find really unfair and frustrating: International Pricing of High End Tech Items. Let’s check out the new Nikon D700:

Nikon d700 Germany: 2,599 eur

Nikon d700 United States: 2,999 usd – 1,825 eur

Nikon d200 Britain 1892 pounds – 2,383 eur

It certainly would seem that Germany is getting the short end of that stick. In many cases, people in Europe could fly to the US, buy electronics, and come back for the price of getting them here. And many people do.

Not to menaion many companies have better warranties in the US where the market is more competitive. (Example: Many Nikon cameras and lenses have a 5 year warranty in the US and 2 year here in Germany)

When the Wii came out int he US, it was 250usd, when it came out here, it was 250eur. The eur was riding high, in the US it was impossible to get a Wii, hwever, they were readily available in all stores here; leading many to speculate that it was because Nintendo was making 400usd per Wii (250eur) in Europe. This isn’t just about inflation, some items are priced 1:1 or a little over, 3dsMax below, but others are more ridiculous, Photoshop for example.

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3dsMax 2009

3dsMax 2009 Germany: 3,900 eur – (4,641 eur with mandatory tax)

3dsMax 2009 United States: 3,495 usd – 2,257 eur

Photoshop CS3

Photoshop CS3 Germany: 1,027 eur

Photoshop CS3 United States: 607 usd – 390 eur

Photoshop CS3 Britain: 500 pounds – 629 eur

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The above is just completely inane. Some companies will tell you they have to charge a premium on products in Europe because it costs extra to localize them. But come on.. Stuff like the above is ridiculous.

When you start looking at really high end tech, items that only have one distributor in Europe, but many in the US; like motion capture systems, the difference in pricing due to 1) inflation 2) companies just charging more in europe and 3) single distributors in a region having no competition, makes it inhibitively expensive (we’re talking tens of thousands of dollars price difference). It would be cheaper to set up a company in the US just to make these purchases, and I am sure people do.

But seriously, Adobe, you should be ashamed of yourselves.

Character Creation Pipeline

Thanks to my brother, Mike, for translating  this from the original japanese [here]

The hero, Snake, and nearly all other characters we animate on the PS3 and make an appearance in the game are restrained to the range of about 5 thousand to 1 million polygons (including the face). Also, in both gameplay and “cutscenes” the same resolution polygon characters are used. This allows for seamless transition between the gameplay and cutscenes and makes it easier for the player to get emotionally involved in the reality of the game.

Furthermore, for all other characters, except crowds, the same resolution of polygon characters are used in game as well as in cutscenes. Separate from the resolution models used on the PS3, high rez data is modeled at the same time to generate a normal map. Wrinkles in clothing and other details are expressed through this normal map, created from the high rez model.

Of all the bones within the character’s body, the number that contain and are driven by animation data is roughly around 21. But, in reality a number of helper (auxiliary) bones are used to supplement motions like twisting in the knees, elbows, arms and legs.  These however are not driven by animation data. Instead, they reference values of the basic animation driven joints and move in like manner.

The same method is employed on the PS3, not just in XSI; all you have to do is extract the helper bones’ definition files from the XSI data and you can achieve the same kind of control on the PS3 as well. (Awesome! Rig syncing constraints and driven bones between DCC app and game engine)
Since there is no actual motion data stored inside the driven-bones, you are able to not only limit the data volume but even in the event that you need to add or delete helper bones, there’s no need to reconvert the motion data- you can just adjust the model data instead.

Shockingly Realistic Facial Animation

Thanks to my brother, Mike, for translating  this from the original japanese [here]

One of the most notable things about MGS4 is its world-leading cutting edge facial animation. Exactly how were these real-to-life facial expressions created?

Since the Metal Gear Solid series is lip-sinked for localization, from a workload standpoint voice analysis software is employed

In MGS4 for example, lip-sinking for Japanese and English were done seperately with different voice analysis software.Other emotions and expressions besides lip-sinking were animated by hand. In nearly all cases, the expression and phoneme elements were worked on together simultaneously, reducing interference and allowing MGS4 to achieve its simultanious world release.

When doing voice analysis, it’s necessary to set parameters for both expression components (i.e., anger, smile, etc.) and phoneme components (all languages) seperately. After setting this up, we need to see how it behaves as a rig. It’s possible to use parameters for the rotation and movement of bones; however, the rig can become more complicated and it can also become more difficult to predict how the bones with transform/change once enveloped. In other words, when facial animation is done by only controlling the bones, ituitively the designer’s job becomes more difficult and he runs into the following two problems: 1) expressing the behavior of bones, and 2) setting parameters for phonemes.

However, with shape animation (even though it has the drawback of linear interpolation) it’s extremely easy to set up parameters for all your phonemes and
expressions. Most of all, it’s adventagous in that the desiger will be able to intuitively predict the result.

For these reasons, this time on our rig we used bone-driven animation based on the results of various parameter shapes.

With this set up, using voice analysis automated animation (not just the mouth, but automatic animation of the tounge and throat phonemes as well) and hand animation for emotions, we are able to achieve an abundance of realistic expressions.

In the following flash movie you can see how smooth muscular expressions are achieved through superb rig setup

Flash Movie:

Facial rig setup pipeline

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1. Lo-poly model driven by shape animation
2. Above that, the constrained bones
3. Polygonal mesh enveloped to the bones
4.Tangent color
5. OpenGL display (wrinkles expressed also with normal map)

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Expressions, phonemes, eyes (eyebrows), and shader driven wrinkle animation are all tab selectable.
Through the combination of various parameters we can create life-like expressions like those shown above.

The most suprising thing is, we developed a tool that automatically sets up this facial rig that allows such sophisticated control. In other words, if you enter the facial model data and run the tool it will automatically identify the optimal position for bones– in this system the tool will create controls that include the preset parameters for emotions. (a smily face, an angry face, etc.) To perform the automated facial rigging, the facial data’s topology information needs to be standardized ahead of time. If you adhere to this one rule, your set up can be done automatically, and all that’s left to do is for the designer to fine-tune the controls and you have a constructed enviorment where you can get right into your facial animation.

Next, a rig that controls the movement of the eyeball and surrounding muscles can also be generated automatically using this tool. Since the area around the eye, like the area surrounding the mouth, is controlled by the simultanious usage of shapes and bones, when you move the eyeball locater you get smooth muscular movement. What’s more, even if you edit the shape, or redefine the configuration of the outline of the eye, it doesn’t disrupt the expression of brow wrinkles or the blinking of the eye in any way.

Behind all the characters that make an appearance in this game, and appeal to the player’s emotions, we have implemented this set up and animation system; and, through it we are able to increase and maintain a high quality user experience.

Under the Hood: The Inner Workings of Animation on Assassin’s Creed

Sylvain Bernard, Animation Director, Ubisoft

Animation:

• All animation was done in 3dsMax with Biped
  • ‘Our animators do not like MotionBuilder for creating animation’
  • Would have meant porting all their tools to MotionBuilder
• MotionBuilder was only used to clean mocap
• They decided to ignore foot sliding in order to concentrate on a better performance and gameplay experience
• They stressed the importance of Technical Animators
• Up to 15 animators worked on Assassin’s Creed
• 40% of all animation was hand keyed
• There is no procedural animation(not counting blending)
• They showed the entire move tree
  • sprint, run, walk, jog, slow walk, banking, strafe, 4 idles
  • 168 ground animations for altair locomotion group
  • 122 anims in climbing group

Production:

• 90% of work was integrating animation into the environment
• The key was pairing animators with programmers
  • Sit them together
• Before they started one main goal of the project was ‘to do as much animation as we could’
  • They saw Next Gen as an animation showcase
• They prototype gameplay in max to show programmers how the game should look/feel
  • How AI should react
  • How a character should interact with the environment
• ‘In the beginning designers were given free reign to make anything they wanted, in the end we had to make a 20 page document telling them how to create levels’
  • Too much freedom leads to chaos
• Stressed the need to involve animators in animation system development

Pipeline/Rigging:

• All characters share the same skeleton (male/female npc, altair)
  • ‘the art director wanted characters of different heights, we said ‘no”
  • made mocking things up easy
• They call their movement locator the ‘magic bug’
  • Locators ‘joined together’ when two characters interacted
• NPCs use simple hinge constraints for ponytails and things
• They had ‘no working AI for almost the first two years‘ of the project
• They do edge detection on the collision mesh
• Auto nav mesh generation
• Auto ‘animation object’ placement

I saw this over at slashdot:

“The US Court of Appeals for the Tenth Circuit has affirmed (PDF) a ruling that a plain, unadorned wireframe model of a Toyota vehicle is not a creative expression protected under copyright law. The court analogized the wire-frame models to photographs: the owner of an object does not have a copyright in all images of the object, but a photographer may have a limited copyright over a particular image based on artistic choices such as costumery, lighting, posing, etc. Thus, the modelers could only copyright any ‘incremental contribution’ they made to Toyota’s vehicles; in the case of plain models, there was nothing new to protect. This could be a two-edged sword — companies that produce goods may not be able to stop modelers from imaging those products, but modelers may not be able to prevent others from copying their work.”

This will have some interesting ramifications. And I don’t just mean for the Limbo of the Lost guys. (j/k)