Deeper with the GeForce 7 Series
PCI Express x16 graphics cardsChipset GeForce 7800GT / 7800GTX 256 MB, 256 bit
After completing our round up, we've decided to conduct more testing to see just what the GeForce 7 series have to offer. Normally, we put up a comparison to its nearest competitor (ATI's Radeon X1800 series of cards), but we're not able to get samples at this time. Hopefully, we will be able to bring you a Radeon X1800 series round up next month. For now, we will be comparing the GeForce 7800GTX and 7800GT with reference clocks, since there are no standard for the higher clocked cards (each vendor used different clocks for their cards). Higher clocked cards should offer slightly higher frame rates (but not much).
From a rendering perspective, the GeForce 7 series is not that much different from NVIDIA's own GeForce 6 series. So, image quality will be the same if not similar between the two. However, there is one major difference - the GeForce 7 series can perform antialiasing on transparent (or alpha) textures, either using multisampling or supersampling. Naturally, we're very interested in this feature and just like we promised in our last article, we will focus on this feature in this article.
Another feature that is also a concern to us (and at least some of you) is of course high dynamic range (HDR) rendering. Although the GeForce 6 series is already capable of HDR rendering, performance with HDR is still too low to offer fluid gameplay. The GeForce 7 series with higher fill rate should be able to provide higher frame rates - we will be using Serious Sam II and Splinter Cell Chaos Theory for HDR performance test. However, just like with the GeForce 6 series, HDR rendering will not work with antialiasing on the GeForce 7 series. So, we will only touch this subject briefly.
In addition to testing with our usual graphics benchmarks, we also perform some additional testing of transparent textures antialiasing with our older game benchmarks as well. We won't be publishing the results (for reasons we will go into later), since we're focusing on compatibility and not performance with these older games. So, without further ado, let's move onward.
Overview
Transparency antialiasing
If you're lucky enough to already have one (or two) cards from the GeForce 7 series, you'll be able to find the option to turn on / off this feature in the driver panel, under the Performance and Quality Settings section. Of course, you'll have to choose Advanced Settings in the Global Driver Settings to actually see and change it. NVIDIA explains transparency antialiasing as" an advanced feature, (is) a technique used to minimize the visible aliasing on the edges of images with transparent textures. This improvement in 3D image quality is most noticeable in objects such as vegetation, chain-link fences, and so on."
If you don't have much interest in 3D graphics, you may be wondering why is this so. Well, here's a quite simplified explanation. Look at a tree, chain-link fence in real life and in games. If game developers were to model the same objects in their game in exact detail, it will take too much time, but more importantly, too slow. So, instead of modeling every single leaf or chain-link, they took (or draw) a picture of a branch with leaves or a chain link fence, then put them into a single texture. To complete the illusion of a tree, they cut off the background and mark the empty area as transparent, so you will only see the branches, leaves or chain-link when the texture is finally rendered on screen. So, game developer can get away with much less polygons and just several textures for that tree or fence.
Since this is a new feature, you have to basically 'force' antialiasing on transparent textures. No game available right now supports transparency antialiasing out of the box. Thankfully, NVIDIA have managed to simplify this feature so you won't have to force the level of antialiasing (2x, 4x, 8xS) from the driver panel. You only need to turn on the option (and the transparency anti aliasing mode - off, multisampling or supersampling) on the driver panel. This way, you can still control the level of antialiasing from a game or application. Unfortunately, there's no way of using different levels of anti aliasing - for example, you may want to use 4x AA on non transparent textures and just 2x (or 2x Quincunx) AA on transparent textures or vice versa.
Now, let's take a look at what transparency antialiasing has to offer, image quality wise. Below you can see a series of screenshots taken from Brothers in Arms with plenty of vegetation. They are in order, without transparency antialiasing, with transparency multisampling antialiasing (MSAA) and last with transparency supersampling antialiasing (SSAA)
The easiest area to focus on is the leaves near the crosshair (the ones with the sky on the background). Well, we didn't really see that much difference - looks like even the performance is the same. You'll no doubt notice that by looking at the FRAPS fps counter on the top left of all three images. Looks like this can explained by two things: either there's no performance drop with any of the transparency antialiasing modes or transparency anti aliasing is not enabled at all (on all images). Now, let's take a look at our second game, Battlefield 2. Again, the images are arranged in this order: without transparency antialiasing, with transparency MSAA and last, with transparency SSAA.
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