Ray Tracing

With launch of RTX cards by Nvidia, ray-tracing is suddenly the hottest technology in the market today. A technology which is not new, but efficient usage of the concept was science fiction even some years back.

Ray tracing is rendering a scene real time using the ambient sources of light. If you are playing FHD @ 60 Hz, then it means rendering 60 scenes of resolution 1920×1080 pixels, per second. Most graphics are rendered today using rasterization, i.e. pre-rendered bitmaps (matrices having RGBA values at each coordinate/ pixel), but ray-tracing is about rendering these values on the go depending on what the sources of light are at a given scene.

If we try to compare a scene ray-traced with the new RTX graphics cards and one rendered using some of the latest game engines (without ray tracing), it will be hard to distinguish, because the contemporary game engines have become that good. In terms of visual fidelity, there is not much difference, so we see most ray-tracing demos showing off over-the-top reflections that look plastic in an attempt to sell the new ‘shiny’ (pun intended) thing. Fortunately, shiny reflections and ultra shadows are not what ray-tracing is actually about.

The real deal of ray-tracing would be to have exactly one high res texture (map) for each object in the game, then render that same object differently with varied lighting. This means if a game engine supports ray tracing, disk size of the game will be much less. Instead of having multiple maps corresponding to each lighting that the game engine needs to support, it will have only one map (at the highest res as otherwise upscaling would be required which does not preserve the fidelity). The variations will now be rendered real time. So ray tracing effectively moves the requirement from storage to processing.

The 1199 dollar question (pun intended) is, though, whether this is going to happen now for ray-tracing supported games which will make these cards worth. A simple comparison of the disk space requirements between Shadow of the Tomb Raider (40 GB, ray-tracing support) and Rise of the Tomb Raider (25 GB, raster graphics) shows that this is not the case. One justification for the higher disk space may be that the new game is also developed for raster-based rendering, so they had to carry excess baggage. Then the thing to look for is that if they have a different, lighter build (game distribution) exclusively for ray-tracing, and as of now, they dont.

This means nothing more than the established cycle of technology – ray tracing (i.e. efficient rendering using the concept) is a new technology, and game engines (i.e. games) are not there yet to fully utilize its potential. In a couple of years we will see new game engines that do real time ray-traced rendering, and only then would ray-tracing cards be useful. And just like any other new technology, prices which are sky-high now will drop to sane levels. Till then, it is wiser to hold on to those TFLOPS kings, or maybe even invest in one as their prices would fall now.