Feature Article: Graphic Glitches 101

Posted Wed May 14, 2008 at 10:00 AM PDT by

Editor's Note: Columnist Wayne Santos is a dedicated gamer from the infancy of the medium. He is a contributor at IGN and associate editor of Southeast Asian gaming publication GameAxis. In this new, semi-regular column, Wayne will be discussing a broad range of topics related to High-Def Gaming.

By Wayne Santos

High-Def Digest already has a rigorous system in place for evaluating the picture quality of movies, documentaries, and concerts that are presented in High Definition. Over the course of the mainstream transition to HD, this has given a lot of neophytes to the world of visual fidelity a good grounding in what they should look out for to discern the difference between a quality transfer and ones that sport minor or even major flaws. With a little information, more and more people can now make out the distinctions in picture quality for themselves, and make more informed decisions about which movies really make the most of their televisions. The same also holds true for games, although the criteria for judging the visual quality of a game does differ. Movies have issues such as artifacts, banding and color. Games have their own issues like frame rates and collision detection, for example.

For many years, the graphical quality of games was severely hindered by the constraints of the hardware, and this was particularly true for consoles, where earlier hardware such as the Nintendo Entertainment System – or even the original Playstation – while considerably more advanced than the clumsy, colored squares of consoles in the 70’s (like the Atari 2600), still required a lot of imagination on the part of the gamers to create a sense of realism and suspension of disbelief that film found so easy to instill in audiences. This is gradually changing now with the introduction of more powerful consoles into the home and the transition into HD gaming, but that doesn’t mean that gaming is anywhere near achieving a degree of photorealism that will instantly fool the human eye. While the visuals in games get more polished and refined, with developers getting a better understanding of the machines they work on, or developing new graphics engines, there are still things that can – and frequently do – slip through the cracks of visual presentation. In this article, we’ll look at the deficiencies or “glitches” that can separate top tier graphical work from more functional efforts. This is meant to be a general introduction, so nothing will get too technical here, and it should help those new to gaming as the result of obtaining a 360 as an HD-DVD player, or a PS3 as a Blu-Ray player, get more familiar with the interactive aspect of their machines.

Frame Rate

When it comes to film, the accepted convention very early in the inception of the medium was 24 frames per second. That is to say, the illusion of movement was created when 24 images were played back in the space of one second. For years this has been the standard, although in recent times with the introduction of HDTV broadcasts, this is starting to change to rates like 60 frames per second. In games however, the frame rate is nowhere near the universal standard that film has enjoyed for decades, and this is chiefly because of the limitations of the technology. While film generally manages to create a sense of movement from 24 frames per second, or fps, that illusion is maintained because of the consistency; except for deliberate camera choices such as slow motion or fast forward, a viewer can generally expect the film to run at 24 fps without ever noticing a dramatic change.

The same however, does not hold true of games. Unlike a digital disc, film reel, or tape, which is used as a playback device, a game console takes the data of the game and must virtually recreate that information as objects and environments that the player can interact with. As a result, the processor of a console is constantly “creating the world” around the player, and depending on how intense the action is – or simply depending on how well the game has been programmed – there can be some variance from the 30 fps or 60 fps that are generally accepted as the standards for the gaming industry today. For example, Grand Theft Auto IV the game which recently took the record for best selling piece of entertainment in a 24 hour period, normally runs at 30 fps. However, the scale of the world the game is trying to create, or “render” can be quite taxing on consoles, and if things get too hectic, for example, causing a gigantic firefight with helicopters, police teams, S.W.A.T. vans, explosions and screaming pedestrians in the virtual equivalent of Times Square, with neon, lights and the occasional explosion from rocket propelled grenades… this much chaos can occasionally strain the 360 or PS3 and will have a noticeable drop in its frame rate, though this doesn’t carry on for very long. On the other hand, games with fewer variables to consider, such as Gran Turismo 5: Prologue have an easier time with more controlled conditions. In the case of GT Prologue, the fact that its resources are devoted to simulating only a track and the behavior of the cars on the track means that it was optimized to display at 60 fps during gameplay and it never drops from this. .

Spotting a drop in the frame rate is one of the easiest glitches to identify as the human eye immediately notices the change in movement. One moment everything is relatively smooth, but as soon the frame rate drops, the eye sees the change as a “stuttered” motion. Depending on the severity of the drop in frame rate, this can even be as serious as the movement no longer appearing to be movement, but instead bearing closer resemblance to a slide-show, with images present for a second or more before moving onto the next. Games today rarely – if ever – experience a drop in frame rate this serious, although in the infancy of gaming, some games actually functioned at far lower frame rates – as low as 6fps – for the simple reason that that was all the retail processors of the time were capable of.

Screen Tearing

Screen Tearing is a relatively recent phenomenon for consoles, although PC gamers have been familiar with this particular glitch for a number of years. The glitch gets its name from the effect it has on the visuals, such as the shot of the original Halo: Combat Evolved shown above. Take careful notice of the area between the player’s gun and soldier to the left. What should be a view of the shore with the water washing up has a section that doesn’t match with the rest of the image, as if the individual section has been shifted or “torn” from the fabric of the rest of the image and isn’t aligning correctly. Screen Tearing is related to frame rate issues in that it’s a conflict between one image and another. In this case, the glitch occurs when a new image is being displayed, but the older image is also still being displayed.

This issue is normally addressed by a technique known as Vertical Synchronization, or Vsync, which is essentially a “gatekeeper” that ensures one image is fully rendered and ready to discard before another image is rendered. However, the dynamic nature of games can still occasionally cause screen tearing to occur, particularly if the action on screen forces the processor to make a choice between keeping the frame rate smooth and displaying some screen tear, or eliminating the screen tear at the cost of dropping the frame rate. This can happen to varying degrees on graphics intensive games, indicating that either the software is pushing the hardware to the limit, or the hardware itself is not being fully utilized. For example God of War 2 on the Playstation 2 had moments of screen tearing, but it was widely accepted that this was simply because the Sony Santa Monica team had pushed the PS2 about as far as it could go, and were using nearly all the resources the machine had with little leeway left for flawless Vsync. On the other hand, early launch efforts like the Xbox 360 First Person Shooter Perfect Dark Zero showed screen tearing simply because the technology was new and the game was rushed out in order to release in time for the launch of the console. It’s usually normal for the first wave or generation of games on a new console to display the most obvious graphical flaws because of the lack of familiarity with the hardware at the time. However, it all rests in the hands of the developer, their understanding of the hardware, and how hard they push the boundaries when it comes to this issue. Even today there are still some high profile games that are occasionally prone to this glitch, such as Gran Turismo 5: Prologue, which has extremely rare occurrences of this glitch, while other games such as the critically acclaimed Mass Effect on the Xbox 360 suffer from it on a regular basis.


This is a graphical glitch that will probably remain an issue for this generation of gaming and beyond. The simple fact of the matter is the current hardware, while impressive, is not all-powerful and it will still hit definite limitations in terms of what it’s capable of displaying. In order to not tax the resources of a machine, developers will normally set a “draw distance” which – in virtual world terms – is the area that game is instructing to the console to display or render. After all, if a player is only going to see, say, the first 30 yards of the environment around him, it’s more economical for the hardware to concern itself with only creating that 30 yard radius the player sees to the fullest possible detail, rather than creating the whole environment to that intricate level for miles around.

This is also where the problems come in. Once again the understanding of the hardware, the quality of the programming and the dynamic nature of games all conspire to make the issue of draw distance a less than straightforward affair, and when things go wrong, that is where pop-up or draw-in can occur. Put simply, this glitch occurs when players are interacting with the world too quickly for the game to keep up, and when the game does finally get back on track with where the player is and what they are doing, the game must suddenly make up for lost time and start rapidly populating the area with the things that are supposed to be in that environment. The clearest example of this is something like Grand Theft Auto IV where the world is truly massive. If players manage to get a good run in a car, hurtling down roads at breakneck speeds, they can be traveling so fast that elements of the game world no longer gradually appear in the distance and get closer as the player approaches. Instead, objects – like trees, lamp posts and even pedestrians – can magically appear out of nowhere as the game finally “catches up” with the player and starts populating the area once it realizes where the player is. Obviously with the previous example of a high speed race, this can mean the player colliding straight into buildings or other obstacles that weren’t there a split second before and have seemingly “teleported” into place before the player’s very eyes. This is pop-up. Draw-in is a similar glitch, which works at a slower pace. Instead of magically appearing in front of the player with no warning, draw-in usually works somewhere in the distance, where the environment actually appears to be quickly “drawn in” before the players very eyes, as if a construction crew were rapidly building up the world a short distance away, trying to finish in time before the player arrives.

Here’s a good example of pop-up courtesy of GameSpot, from the game Elder Scrolls IV: Oblivion

For the example above, imagine that the player has just teleported into the area, and this what they see when they first arrive; a hut and a fence. However, a second later, this happens:

The world has suddenly become more populated with trees, horses, even a sign on the hut. The game has finally caught up with the location of the gamer, and in a hasty effort to get back on track with what the player is supposed to see in this area, it has made all the extra objects instantaneously appear. This is not a problem that is going to go away any time soon, as developers are constantly pushing the hardware to create bigger, more detailed and expansive worlds. Pop-up and draw-in can be hidden to some degree, something that racing games excel at, by hiding the places where these glitches occur thanks to natural obstacles such as turns or even mountain walls that can obscure the objects normally viewable at a distance. But as consoles get more powerful, developers will be constantly encouraged to push the limits of that hardware, and as such the pop-up and draw-in issues will likely still be with us for a while until developers either truly master the “cheats” to hide it from players, or else hardware becomes powerful enough that it’s feasible to simply render everything in high detail within the viewable distance in real time.


The above screenshot is from 1998’s Ridge Racer 4 on the original Playstation and is an extreme example of an issue that still occasionally crops up in games today, aliasing or “jaggies.” This is the clear, “stair step” effect that registers on our eyes when we see something displayed at lower resolution. Of course, higher resolutions have helped clean this up considerably in recent years, but the feature most responsible for giving us cleaner images is called Anti-Aliasing, which is simply devoting more processing power and specific programming techniques to “smoothing out” those edges and giving images a more naturalistic look in line with what we’re accustomed to seeing in real life. Compare the above image from 10 years ago that had no Anti-Aliasing on the original Playstation with Gran Turismo 5: Prologue on the PS3 to see what a difference “AA” as well as increased polygon counts and a host of other graphical upgrades can have on a game’s visuals.

Aliasing is another glitch that has become less pronounced in this new HD generation of games, although, surprisingly, it can still crop up. AA, like everything else about a game, will demand certain resources from the system, and as a result, sometimes developers will deliberately choose not to maximize this feature for a particular game if it means compromising the game in some other way, such as dropping the frame rate as the hardware struggles to smooth out everything on screen. It is this delicate balance between all these graphical considerations that forces developers to perform a juggling act of sorts, deciding on draw distances, AA and many, many other considerations to keep the game playable versus keeping the game beautiful. Games with longer draw distances and little pop up or draw in might suffer from more aliasing issues. Games with smoother frame rates and lots of anti-aliasing might suffer from smaller environments, etc, etc. In a sense, aside from the actual monetary cost of developing the game, the game developers have the additional worry of a “technological budget” where they must consider what sacrifices they make – and to what degree – in order to create a game that the audience will find both visually pleasing but also fun to actually play. Frequently they fail to strike the right balance, as evinced by the wealth of games that don’t meet up to either playability or graphical quality, whereas games that successfully do both are rare indeed.

Collision Detection/Clipping

The final glitch is one that doesn’t necessarily detract from the overall quality of the visuals, but has a tendency to break immersion more noticeably when it occurs. One of the fundamental rules of Newton states that – at least on the level of reality we’re familiar with – two objects cannot occupy the same space. Poor collision detection ( or “clipping” a nick name picked up from the game Doom from a built-in developer cheat called “No Clip”) is when for reasons of time or simple neglect, developers release a game in which virtual objects break this fundamental law. If you look closely at the above screenshot from famed online virtual reality Second Life, you’ll see a few examples of this in action. The man with the sunglasses has his right hand passing into his thigh, and to his left, the Smurf’s TNT is actually sinking into his thighs as well.

Poor collision detection is a fairly common glitch because it requires an enormous amount of time and care to properly address it. Usually game developers simply don’t have the luxury of that time or attention to detail because it would mean delaying a game that people are already screaming for in order to address what most would regard as a small nit-pick. These days, the most common times you’ll see poor collision detection in action is during shooters where players must kill other opponents. Usually collision detection is spot on and works as expected when everyone is alive, but when characters are killed, it’s not unusual for the game to no longer regard the victims as “objects” and often heads, legs and other extremities will now pass through walls in ghost-like fashion, since the game no longer deems it necessary to pay the same amount of attention to detail to an essentially “finished” asset of the game. It’s not the kind of thing that normally interferes with gameplay, at least not to the extent that a drop in frame-rate can, which is the most serious glitch, but poor collision detection is the one that most pulls the gamer out of the world the developers are trying to immerse people in, and remind them of the artificial nature of the game they are playing.

As with movies, these visual flaws are normally very minor things that don’t necessarily detract from the overall quality of a game, unless they reach serious levels. It wasn’t even until the last two generations that Anti-Aliasing was even a practical feature for console games, and plenty of games received critical acclaim without AA. But, as with film, the additional technology can enhance the gaming experience and contribute to the sense of suspension of disbelief, provided that the fundamentals – that is a strong game, with a compelling mechanics – is there to begin with. Like film, games are a marriage of elements, and if the gameplay isn’t there, the character isn’t there, and the story isn’t there, then all the visual fidelity in the world is not going to save that game from being a critical and commercial failure. Glitches such as the ones listed above can either be minor blemishes to an otherwise masterful game, or be more damning flaws in an already poor one.

Wayne Santos's opinions are his own and do not necessarily reflect those of this site, its owners or employees.

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