Architectural_Design_with_SketchUp

Chapter 5 Rendering in SketchUp
at the edges of the lawn, where blades overlap walkways. If you bent down to get even
closer, you would then see that not only is each blade curved, it also has a V shape in cross
section. As you can see from this example, your approach to modeling and rendering must
vary, depending on the distance of the viewer from the object.
Figure 5.87 illustrates the four approaches you can take.
Figure 5.87: Grass rendering methods (left to right: SketchUp’s grass texture, same with bump, individual blades, 2D image patch)
When your distance to the grass is quite far, it might be enough to simply use SketchUp’s
grass texture (or any other uniformly patterned tiling grass texture). This is shown in the leftmost
image of Figure 5.87.
This method improves when you add a strong bump to the grass material in your rendering
software. The deep shadows that appear give the grass more realism, as you can see in
the second image from the left. You can evaluate the appropriateness of this approach when
you are at arm’s length from the image—this rendering should appear reasonably realistic.
The third image shows the other end of the effort spectrum. This is what we get when
we model each blade separately. I used the Fur plugin (from Chapter 4) to do this and went
with its default arch shape. As you can see in the third image from the left, this approach
leads to an excellent degree of realism—even when the viewer is as close as we are to this
image. A major downside of this approach, however, is the very large number of polygons
that this method creates, which not only increases rendering time but can also slow SketchUp
significantly if you are not careful. Use it mostly for close-ups.
A good compromise between those two approaches is to use a 2D image of a grass patch
(see Figure 5.88), which contains a transparent background (a transparent PNG, in my case).
Especially when you use a low-resolution image, this approach can significantly reduce the
polygon count in your model. I also used the Fur plugin, as before, but this time let it place
copies of the image component instead of individual blades. You can evaluate the result in
the far-right image in Figure 5.87.
As you can see, this leads to quite a good rendering. Each grass-patch image (representing
many blades) triangulates as two polygons, while each individual blade in the last method
turned into five—making this method much more polygon-efficient. The only problem with
this approach are occasional patches (you can see some in the foreground) and a bit of a
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