New Article: Ray Tracing and DLSS Testing in Shadow of the Tomb Raider

It has been a long time since the first graphics cards based on Turing family chips appeared on the market. At the moment, the catalog of "green" accelerators includes four models capable of performing real-time ray tracing, but NVIDIA will not stop there - already in mid-April, support for DXR and Vulkan RT interfaces will be acquired by video cards of the GeForce GTX 16 series and most accelerators based on Pascal chips, starting with the GeForce GTX 1060 with 6 GB of RAM. Here are just games that already use DXR or DLSS technology, based on machine learning and Turing architecture tensor cores, so far can be counted on the fingers of one hand. And on the fingers of the other - upcoming projects with such opportunities.

The glory of the pioneers has already gone to Battlefield V and Final Fantasy XV, and recently Metro Exodus thundered. Shadow of the Tomb Raider went gold back in September last year, and most fans of the series didn't wait for the Eidos team, in collaboration with Crystal Dynamics, to endow the game with DXR and DLSS support. We did not wait when we released a group test of video cards in Shadow of the Tomb Raider. But now the promised update has appeared, which means that our work with this game is not over yet.

Ray tracing examples

Last August, NVIDIA showed off an impressive segment from Shadow of the Tomb Raider, in which ray tracing literally transforms the picture. But for those gamers who are in no hurry to shop for new generation graphics cards or have postponed getting to know the game until the recent DXR patch, it is better to adjust their expectations. After all, the term Ray Tracing in Shadow of the Tomb Raider from the very beginning referred only to shadows from objects that are in the rays of direct light sources.

Considering that a good part of Lara Croft's adventures take place underground, there are quite a few such scenes in Shadow of the Tomb Raider. Without DXR, the engine uses dynamic shadow maps to render direct lighting effects. This method is somewhat similar to tracing in that shadow maps are formed by separately projecting the scene from a viewpoint that matches the light source, but has known drawbacks. Thus, shadow maps are not very accurate, work only with point light sources and do not form silhouettes with soft outlines without an additional edge blur operation. And in order to save computing resources, as a rule, only selected objects of the scene are placed in shadow maps. Ray tracing does not have these overheads, and in the right situations, Shadow of the Tomb Raider changes dramatically - those who have already completed the game should repeat the journey to see it with their own eyes.

But alas, the influence of DXR in Shadow of the Tomb Raider is limited to direct light sources. Reflected light is still implemented with static methods baked in the map editor, with a dynamic add-on in the form of Ambient Occlusion. After Metro Exodus, where the developers transferred the entire global illumination model to ray tracing, the half-hearted approach of Shadow of the Tomb Raider is already hard to come to terms with. In addition, it is easy to see from the screenshots how much the depth of the shadows changes depending on the DXR settings. In other scenes, it's hard to see the difference between tracing at the Medium level and standard shadow maps. In addition, even at high DXR quality levels, stepped silhouettes are noticeable as a consequence of the low beam density.

Image quality: DLSS vs TAA

Ray tracing, even in a limited format, as it is done in Shadow of the Tomb Raider, greatly affects the performance of the GPU, and this is already a very demanding project at high graphics quality settings. To compensate for the inevitable hit to framerate, the game's developers implemented DLSS support at the same time as DXR. We've written about NVIDIA's proprietary technology that allows the GPU to render at reduced resolution and then scale the frame using a neural network powered by Turing tensor cores. However, the practical experience that gave Battlefield V, Final Fantasy XV and Metro Exodus, has already destroyed all illusions about the quality of DLSS at the initial stage of its distribution. Of the three pioneering games, only Final Fantasy XV's DLSS product is comparable to direct rendering at the target resolution, and even then with a lot of caveats.

Needless to say, we didn't expect outstanding results from DLSS in Shadow of the Tomb Raider? However, the game gave us a pleasant surprise. In the few shots we shot using DLSS and TAA, a widely used and undemanding method of full-screen anti-aliasing, it's hard to see any difference in clarity at first glance. DLSS is especially good at handling texture detail on large surfaces. Even in objects such as plant foliage and hair, there is almost no blur. For comparison, here are similar screenshots taken in 1440p mode and simply scaled up to the target resolution of 2160p by the game engine (for this, you need to disable the exclusive full-screen mode option).

However, we have already managed to make sure that in all games using DLSS, there are no two identical neural networks. The algorithm inherent in Shadow of the Tomb Raider has oddities that we have not encountered before. DLSS is too tough for image elements with lots of thin lines that appear to be superimposed on top of a transparent texture - bicycle spokes, ivy on the walls of a building, and the like. These sections of the frame look like DLSS is not even trying to increase the resolution.

In addition, in particularly complex scenes (for example, in the depths of the jungle), the neural network sometimes becomes disoriented and begins to blur objects that it otherwise processes with reference clarity (such as the clothes and hair of the main character). With a sharp movement of the camera, false patterns appear on the roofs of corrugated metal (however, they are just impossible to see in motion). Finally, DLSS noticeably enhances the overall contrast, regardless of the content of the frame. But this is already nit-picking. In total, Shadow of the Tomb Raider achieved the best results of the four games with DLSS support - we strongly recommend enabling this option, especially at 2160p in combination with DXR.

Test stand, testing methodology

Test stand
CPU	Intel Core i9-9900K (4,9GHz, 4,8GHz in AVX, fixed frequency)
Motherboard	ASUS MAXIMUS XI APEX
RAM	G.Skill Trident Z RGB F4-3200C14D-16GTZR, 2×8 GB (3200 MHz, CL14)
ROM	Intel SSD 760p, 1024 GB
Power supply unit	Corsair AX1200i 1200W
CPU cooling system	Corsair Hydro Series H115i
Chassis	CoolerMaster Test Bench V1.0
Monitor	NEC EA244UHD
Operating system	Windows 10 Pro x64
AMD GPU software
All video cards	AMD Radeon Software Adrenaline 2019 Edition 19.3.2
NVIDIA GPU software
All video cards	NVIDIA GeForce Game Ready Driver 419.35

Performance testing was done using the built-in Shadow of the Tomb Raider benchmark with all graphics options maxed out (with the exception of FSAA and DXR, which we vary in the tests). The average and minimum frame rates are derived from an array of individual frame render times that the game writes to the results file.

The average frame rate in the charts is the reciprocal of the average frame rendering time. To estimate the minimum frame rate, the number of frames generated in each second of the test is calculated. From this array of numbers, the value corresponding to the 1st percentile of the distribution is taken.

Test participants

• NVIDIA GeForce RTX 2080 Ti Founders Edition (1350/14000 MHz, 11 GB);
• NVIDIA GeForce GTX 2080 Founders Edition (1515/14000 MHz, 8 GB);
• NVIDIA GeForce RTX 2070 Founders Edition (1410/14000 MHz, 8 GB);
• NVIDIA GeForce RTX 2060 Founders Edition (1365/14000 MHz, 6 GB).

Source: 3dnews.ru