HA4 Task 6 – Constraints

What constraints are involved in working within a 3D environment - polygon count, file size and rendering time?

Remember that you are trying to comprehensively explain the theory and applications of 3D with elucidated examples and consistently using subject terminology correctly.



Polygon Count

The two common measurements of a game character's 'cost' are polygon count and vertex count. Polygon is interchangeable with triangle in these measurements, as GPUs only see vertices and triangles, not 4 sided polygons. Depending on the use, a game character may stretch anywhere from 200-300 triangles, to 40,000+ triangles. A high-end third-person console or PC game may use many vertices or triangles per character, and an iOS tower defense game might use very few per character.

When a game artist talks about the polygon count of a game design, he really means the triangle count of the model itself. Game always have a triangle count within them instead of polygons, because most modern graphic hardware is built to accelerate the rendering of triangles. The polygon count that's reported in a modeling app is almost always incorrect, because a model's triangle count is higher. It's usually best therefore to switch the polygon counter to a triangle counter in your modeling app, so you're using the same counting method everyone else is using. Polygons however do have a useful purpose in game development. A model made of mostly four-sided polygons  will work well with edge-loop selection & transform methods that speed up modeling, make it easier to judge the "flow" of a model, and make it easier to weight a skinned model to its bones.
Source:http://www.shapeways.com/blog/uploads/cars_low.jpg
Source:http://gyazo.com/54622e08bd04da1efcd040c8c32df89b.png

File Size 

File size for 3D Modelling or any other kind of creation, is vital. Without file size you will not be able to save/create your project to begin with. And considering having a high polygon count in your 3D environment in particular, will make this even more difficult. Another valuable thing to have with creating 3D assets is a good CPU ( Central Processing Unit) that will have you render your work fast and efficiently although good CPU's come at a hefty price.
Source:http://www.foldersizes.com/images/v6/tour/file_sizes.jpg

Rendering Time

Rendering is the final process of creating the actual 2D image or animation from the prepared scene. This can be compared to taking a photo or filming the scene after the setup is finished in real life. Several different, and often specialised, rendering methods have been developed. Rendering is the most technically complex aspect of 3D production, but it can actually be understood quite easily in the context of an analogy: Much like a film photographer must develop and print his photos before they can be displayed, computer graphics professionals are burdened a similar necessity.

There are two major types of rendering, their chief difference being the speed at which images are computed and finalized.

Real Time Rendering

Real-Time Rendering is used most prominently in gaming and interactive graphics, where images must be computed from 3D information at an incredibly rapid pace.

Interactivity: Because it is impossible to predict exactly how a player will interact with the game environment, images must be rendered in “real-time” as the action unfolds.

Speed Matters: In order for motion to appear fluid, a minimum of 18 - 20 frames per second must be rendered to the screen. Anything less than this and action will appear choppy.

Methods Of Real Time Rendering: Real-time rendering is drastically improved by dedicated graphics hardware (GPUs), and by pre-compiling as much information as possible. A great deal of a game environment’s lighting information is pre-computed and “baked” directly into the environment’s texture files to improve render speed.

Source:http://en.wikipedia.org/wiki/Real-time_rendering

Non-Real Time Rendering

Non real time rendering, also known as ''offline'' rendering, is used in situations where speed is less of an issue, with calculations typically performed using multi-core CPUs rather than dedicated graphics hardware.

Predictability: Offline rendering is seen most frequently in animation and effects work where visual complexity and photorealism are held to a much higher standard. Since there is no unpredictability as to what will appear in each frame, large studios have been known to dedicate up to 90 hours render time to individual frames.

Photorealism: Because offline rendering occurs within an open ended time-frame, higher levels of photorealism can be achieved than with real-time rendering. Characters, environments, and their associated textures and lights are typically allowed higher polygon counts, and 4k (or higher) resolution texture files.
Source:http://en.wikipedia.org/wiki/3D_rendering