Myrtle, fetch the mower!

Convincing sim airports are built of many things, most of which we can pretty much all agree on. Hangars are shaped a certain way, pavement looks like asphalt or concrete or gravel, vehicles either have the right look or they don’t. Where things get a bit more subjective are in the tiny, organic details – grass, for instance.

For some time now, there’s been an expectation that smaller airports (and for that matter, most larger ones) will at least try to incorporate some representation of grass. It might just be a fringe around the taxiways at an international hub, or it might involve a full-blown tangle of thick vegetation that threatens to overwhelm the whole field.

In our latest project, we asked ourselves, “what makes realistic grass look, well, realistic?” Since the airport in question is a smaller GA field, there was no doubt that the natural elements would play a key role in “selling” the believability. So rather than plunking down some grass from one of our existing libraries, we decided to go back to the drawing board and find as perfect a balance as we could between performance and plausibility. We’re pretty happy with the result.

They key elements were:

  • Coloring – The grass had to seamlessly match the photoreal ground beneath it. After all, that image is essentially a top-down view of the actual grass on the field.
  • Variety – Like most organic elements, there’s a lot of variation of color, texture, and density in a field of grass. In some seasons, that includes a splash of wildflowers here and there as well.
  • Performance – We’re trying to fool the eye into seeing hundreds of thousands of blades of grass while laying down a few hundred polygons. That means striking a balance between what’s actually there and what looks like it’s there.
  • Blending – After all that work, the last thing we want is for someone to look at a field and think, “yep, there are a bunch of polygons trying their best to be grass.” We want you to peer out through the windscreen and just think, “grass.” We paid a lot of attention to the best way to hide those straight 3D model edges the human eye has such an affinity for, but which look out of place in a natural setting.

Of course, in the real world many airports are meticulously maintained, including regular mowing. That means that the grass is seldom more than a few inches high. For our simulated environment, we’ve relaxed that standard a bit and let it get higher without being out of control. The result, we hope you agree, is quite believable…