Feature Articles

The Power of 3 - Investigating the Trinity

By Kenny Yeo & Vijay Anand - 1 Nov 2009

Unigine Heaven Results

Unigine Heaven Results

Unigine's Heaven benchmark is the one of the first benchmarks in the world to take full advantage of DirectX 11's tessellation feature. Running with tessellation disabled, we found that the NVIDIA/Intel systems were noticeably quicker when running at 1280 x 1024 and 1600 x 1200. At 1920 x 1440 however, their performance dipped considerably.

 

Running the benchmark with the Radeon 5870, we can fully appreciate the extra details that tessellation brings about. Here are some screenshots and a video.

Tessellation Disabled

Tessellation Enabled (Note how much more textured the stone roads are now. The dragon is also more detailed.)

While it is undeniable that tessellation adds a ton of details to the scene, the thing about such a feature is that unless you are aware, you won't know what's missing. For example, if we showed just the screenshot that wasn't tessellated and told you that tessellation was in fact enabled, would you have known we were pulling a fast one? That's the problem with tessellation as well as rest of the DirectX 11 features.

In terms of perception and final render output quality, there's really nothing that a DX9.0c level of game can't recreate what a DX10 or DX11 based game does. There's nothing to make one go "Wow" from a DX11 scene which could not have already been seen on a DX9.0c level of implementation. What DirectX 11 does is improving the efficiency of recreating these wonderful scenes and thus making it more commonplace than having more work done prior to DX11 that could possibly cause the game developer to consider dropping certain features or reduce the level of realism to make the game more playable on more hardware.

The thing to understand about tessellation is that it allows a much lower polygon count based model or mesh to be tessellated into a high resolution, high quality mesh, without the added memory hogging nature if the GPU were to process a high resolution mesh from the very beginning. And due to its much smaller memory footprint, it is potentially faster to render such a model.

Now back to this benchmark, if you have taken in what we've mentioned above, this Heaven benchmark from Unigine isn't a good one at all for contrasting the differentiation of running the benchmark in different DirectX standards. If you look at our own screenshots, the staircase is more like a ramp plastered with a rock texture when run in DirectX 9/10 or when having Tessellation off. Honestly, what game would even render such a simple thing such as a staircase with such a mismatch of reality?

So is the benchmark rubbish? Somewhat yes, but not entirely. The purpose of the benchmark is to show off just how well tessellation works - and that it does show. What it's not showing is running it in a true DX9.0c or DX10 code path to show the performance differential to bring the same quality levels as seen with tessellation turned on while running the DX11 code path. This means if DX9.0c or DX10 code path is set/chosen, the benchmark should have been able to render what we saw with DX11, but instead of tessellation working in the background, more complex meshes should have been used with differing level of details. All this means the memory footprint required on those older standards would have been very much heavier on those older processing paths, thus a bigger performance loss than when running it in DX11 while the rendered quality level remains similar across the board. Now this would have been the perfect benchmark but alas it's falling short on this aspect. To illustrate the point that even DirectX 9.0c can immerse one with equally stunning quality, here's a discucssion page Overclock.net showing Crysis in DX9 mode with Parallax ocullsion mapping .

Instead the Heaven benchmark from Unigene chose to maintain the same lower quality meshes when running in any DirectX standard. With that being the case, it's only natural that the DirectX 11 version with tessellation enabled showcased much better 'realism'. Here's another discussion thread from Overclock.net showing what we've just discussed upon. As a result, turning on tessellation 'seemed' to have an adverse effect on performance when the realism and quality levels aren't even the same to begin with.

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