So welcome for computer graphics.

I just want to finish a chapter that we started last time.

It's a kind of preview on advanced techniques

and nice tricks that can be done together with texturing.

And so one technique is what we call bump mapping

or normal mapping.

And the idea of normal mapping can be well explained

with this example here.

So the idea is that additionally to the texture showing

the continents here, and that is blue for the oceans and so on,

there's another texture applied in this example.

And the color values of this texture

are interpreted as normals that are used for shading.

So what we see here is a rendering

of a rather simple sphere.

It's not very finely tessellated.

It's rather coarse.

I think we can even, here I think

you can even see that the silhouette is still

quite polygonal.

So it's rather big triangles.

But on these triangles, we see a rather fine,

yeah, we perceive it as a geometric structure.

But in fact, this only comes from taking

a normal which is different from the real surface normal.

And this normal is stored at much higher resolution

than the original mesh would allow in a texture.

And of course, that's complete fake.

The geometry, the render geometry is flat.

But only by applying this normal map,

it looks visually much more interesting.

And yeah, so this can be applied in scenarios like this.

And another application is simplification of models.

So this is an example of a rather detailed model.

And this can geometrically be simplified.

We don't speak about this here in this lecture.

But there are many methods to do that.

But of course, lots of detail gets lost here.

And also a lot of triangles.

So this is more than 100,000.

And this is something like 500.

And this missing detail now here is reintroduced

by adding such a normal map.

And then we have this result.

And this is the low poly mesh now

with such a bump or normal map applied.

And this is the original.

So the difference is really rather small.

And only if you get very close, you will see the difference.

OK, and one important part I spoke about last time