Understanding... Wavelengths for Remote Sensing

在卫星图像处于丰富的时候，对于地理空间家来说很重要，以更深入地了解他们正在使用的数据。在下面的文章中，Niall Conway以轻松的方式审查了光波长后面的一些重要概念，以及它们如何与遥感活动相关。

关于遥感，卫星和实时图像等东西的写作是一切的乐趣。这是当这些领域的专家开始讨论更新的技术方面，即事情可能会出现不舒服的色带，归一化差异植被指数或“假”彩色图像。以下文章将尝试解释一个主要概念之一，即地理学家可能需要了解它们是否有史以来陷入电梯，其中一组物理学家波长。

Imagery is captured using either active sensors or passive sensors. These sensors record the wavelengths of visible light which are emitted from their point of focus.

波长是指测量光的方法。一个波长是指两个连续波谷或波峰之间的距离。这样，光被分类为电磁频谱内的不同类型 - 每种类型取决于发射波长之间的距离。

The largest types of waves are called radio waves. These are used to transmit television and radio programmes. They can either be very big or very small (i.e. between several hundred feet and the size of a coin.)

在无线电波之后，我们进入了光通信的波浪。第一光波被称为红外波。这些比无线电波（围绕针头的宽度）小，并且它们发热。红外线的一个很好的例子是厨房灯的类型，用于在餐厅保持食物。

After infrared waves, we're at the point when waves start to get really, really, really small... as in the size of molecules, atoms and nuclei.

First come the type of waves which keep map-makers in employment - visible waves. As the name implies, these are the only waves in the electromagnetic spectrum which humans can actually see, and each colour in the spectrum appears in the same sequence as it would in a rainbow. Red has the longest wavelength (followed by blue and green), and violet has the shortest wavelength.

A blink of the eye later, we're back into the invisible wavelengths territory! First up, and moving on from the final colour in the visible spectrum, is ultraviolet, or UV waves. These type of waves come from things like the sun or high power welding machines. Due to the radiation emitted, UV waves can be very dangerous if over-exposed to them!

紫外线后，我们进入了X射线的世界。这些非常明显。但是，如果您想了解更多关于X-Ray的信息，请询问您的当地医生 - 我相信他或她会很高兴讨论电磁谱。特别是如果它在时钟！

我们知道的最终和最小的波浪是伽玛射线。但是，除非您正在进行高级医学科学或花时间打击外星人，否则您可能对这些光线很少使用！

谈到电磁频谱的关键是，虽然可见波是人类可以看到的唯一一个，但是由于更复杂的传感器技术，其他类别的波浪是被捕获并更大的遥控器传感专家。最终，这将有助于我们更全面地了解我们的星球正在发生的事情。令人兴奋的时代。

本文于2018年2月出版于GIS Professional