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But we don't keep all this information confidential.
但我们不会对这些信息保密。
We then need to publish our findings so that other people can access it and be informed by it.
然后，我们需要公布我们的发现，以便其他人可以访问它并从中获得信息。
And one way in which this information can be published is in the form of maps.
发布这些信息的一种方式是以地图的形式。
You'll all have used one at some stage of your life already.
你们在人生的某个阶段都已经用过了。
Let's consider the benefits of maps from a geographer's perspective.
现在让我们从地理学家的角度来考虑地图的好处。
Maps can be folded and put in a pocket and can provide a great store of reference when they're collected into an atlas.
地图可以折叠起来放在口袋里，当它们汇编成一本地图册时，可以提供大量的参考资料。
They can depict the physical features of the entire planet if necessary, or, just a small part of it in much greater detail.
如果有必要，它们可以描绘出整个星球的物理特征，或者，只是一小部分的细节。
But there is a drawback. You can't exactly replicate something that is three-dimensional, like our planet, on a flat piece of paper,
但有一个缺点。你不可能在一张平面的纸上精确地复制三维的东西，比如我们的星球，
because paper has only two dimensions, and that means there'll always be a certain degree of distortion on a map. It can't be avoided.
因为纸只有二维，这意味着地图上总是会有一定程度的扭曲。这是无法避免的。
We can also use aerial photographs... pictures taken by cameras at high altitude above the earth.
我们也可以使用航拍照片...这些照片是由相机在地球上空的高海拔处拍摄的。
These are great for showing all kinds of geographical features that are not easy to see from the ground.
这些对展示不容易从地面上看到的各种地理特征来说很有帮助。
You can easily illustrate areas of diseased trees or how much traffic is on the roads at a given time or information about deep sea beds, for example.
例如，你们可以很容易地阐明患病树木的区域，或者在给定时间内道路上的交通流量或有关深海海床的信息。
Then there are Landsats. These are satellites that circle the earth and transmit visual information to computers at receiving stations.
然后是陆地卫星。这些卫星环绕地球运行，向接收站的计算机传输视觉信息。
They circle the earth several times a day and can provide a mass of information -- you'll all be familiar with the information they give us about the weather, for example.
它们每天会绕地球几圈，可以提供大量的信息--比如，你们都很熟悉的、它们提供给我们的天气信息。
So, what we're going to do now is look at a short presentation in which you'll see all these tools...
所以，我们现在要做的是看一个简短的演示，你会看到所有这些工具...
