3.1浏览用户界面

下图是您第一次访问 GEE 主页时将看到的内容。下面列出的是了解我们将在这些模块中定期访问的功能的快速指南。有关整个用户界面的更详细介绍，请单击屏幕右上角的图标，然后从下拉菜单中单击“功能导览”。

Google 地球引擎界面。按照下面的编号了解每个交互部分的扩展定义。
 

1. 搜索栏
   这是 GEE 用户可用的无数数据集的便捷快捷方式。搜索城市名称（“地点”）是放大到所需地理位置的便捷方式。
    
2. 左面板
   
               脚本
               在此选项卡中，您保存的任何脚本都将列在“所有者”下。单击脚本的名称将在脚本编辑器窗格中打开其内容。值得庆幸的是，如果在打开新脚本之前有任何未保存的更改，GEE 会提供警告。
   
               文档
               在此选项卡中，您将看到编写脚本时要使用的可用函数的分类列表。单击函数名称会显示其定义和要求。在脚本编辑器中，如果您只能记住部分函数名称，则可以通过按 ctrl-space（Mac 上为 cmd-space）调出建议列表来避免查找它。
   
               资产
               您上传到 GEE 的所有文件都将在此选项卡中列出。单击文件名会显示有关文件的一些基本信息，并为您提供导入、共享或删除的选项。更多关于资产的内容将在             模块 4中介绍。
    
3. 脚本编辑器
   这就是神奇发生的地方！所有 GEE 脚本都是用 javascript 编写的（参见第 3.2 节），可以通过单击“运行”按钮或按 ctrl-enter（Mac 上为 cmd-enter）来激活。提醒一句：一定要尽早并经常保存。没有自动保存功能！
    
4. Right Panel
   
               Inspector
               打开此选项卡会更改我们与 Map Viewer 的交互。鼠标光标变为十字准线，单击地图可让我们从特定纬度和经度中采样数据。更多关于“检查器”选项卡的内容将在模块 3中介绍。
   
               控制台
               这是 GEE 加载时的默认选项卡，包含与在脚本编辑器中访问的数据相关的有用信息以及统计打印输出和错误消息。
   
               任务
               在此选项卡中，我们可以跟踪导出/下载队列中任何数据的进度。模块 4将介绍更多关于将数据移出 GEE 的内容。
    
5. 地图查看器
   最后，我们所有的图像可视化都将在此窗格中进行。该地图以与谷歌地图相似的方式运行，带有 GEE 专业插件，例如绘制形状和切换可见或隐藏图层的能力。
    

3.2 JavaScript 简介

GEE 代码编辑器中的所有脚本都是用 JavaScript (JS) 编写的。如果您不熟悉这种编程语言，请不要害怕！JS 有大量的在线资源，而 GEE 实际上对遵守所有规则相当宽松。例如，JS 的标准协议是以分号 (;) 结束每个命令。但是，如果您碰巧忘记了一个，GEE 会在（经常）顺利运行您的代码时提醒您。有关 JS 的结构以及如何在 GEE 中使用它的更多详细信息，请单击此处。
 

3.3数据类型：栅格

GEE 中使用的主要数据类型是栅格，涵盖从本地到全球范围的图像，可从数百个卫星和航空资源获得图像。要开始编写您的第一个脚本，请将下面的代码复制到脚本编辑器窗格中。此代码请求来自 NAIP影像集合的栅格。但是，请求图像集合意味着我们可以访问集合中的所有数据——这比我们实际需要的要多得多。使用该filterDate() 功能修改我们的原始收藏并限制图像数量。

<span style="color:#333333"><span style="background-color:#ffffff"><span style="color:#333333"><span style="background-color:#f8f8f8"><code><span style="color:inherit"><span style="color:#8f5902"><em>// Call in NAIP imagery as an image collection.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> NAIP <span style="color:#ce5c00"><strong>=</strong></span> ee<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">ImageCollection</span>(<span style="color:#4e9a06">"USDA/NAIP/DOQQ"</span>)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Filter your dataset from the entire collection to the year of interest and extent.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> naip2011 <span style="color:#ce5c00"><strong>=</strong></span> NAIP</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterDate</span>(<span style="color:#4e9a06">"2011-01-01"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2011-12-31"</span>)<span style="color:#ce5c00"><strong>;</strong></span></span></code></span></span></span></span>

此代码设置了用于显示或运行对 NAIP 图像集合的一部分进行分析的框架，但仅此而已。在我们为 GEE 提供一个可执行任务之前，它不会对这些信息做任何事情。这意味着当你点击运行时，什么也没有发生。这有点令人困惑，但将 GEE 视为一个懒惰的软件程序。您可以给它指示，但在您请求可交付结果之前，它将推迟执行指示。

<span style="color:#333333"><span style="background-color:#ffffff"><span style="color:#333333"><span style="background-color:#f8f8f8"><code><span style="color:inherit"><span style="color:#8f5902"><em>// Define visualization parameters.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsFalse <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'N'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsTrue <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'B'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Add 2011 imagery to the map with false color and true color composites</em></span></span>
<span style="color:inherit"><span style="color:#8f5902"><em>// here we specify either 'true; or 'false' in the third argument to toggle the layer to show automatically or to stay hidden when the code is exicuted. </em></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsFalse<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2011_false"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>true</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsTrue<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2011_true"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span></code></span></span></span></span>

3.4数据类型：向量

在其他 GIS 和遥感系统中，点、线和多边形通常被归类为“矢量”对象。在 GEE 中，这些数据被称为几何。一般来说，您将负责上传或创建您希望在 GEE 中使用的几何特征。您可以使用下述任一技术手动创建感兴趣区域 (AOI)。

<span style="color:#333333"><span style="background-color:#ffffff"><span style="color:#333333"><span style="background-color:#f8f8f8"><code><span style="color:inherit"><span style="color:#8f5902"><em>// Enter the desired coordinates for the upper left and lower right corners of your study area.</em></span></span>
<span style="color:inherit"><span style="color:#8f5902"><em>// You can find the lat long coordinates by using the inspector.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> bounds <span style="color:#ce5c00"><strong>=</strong></span> ee<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#c4a000">Geometry</span><span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">Rectangle</span>([[<span style="color:#ce5c00"><strong>-</strong></span><span style="color:#0000cf">105.53</span><span style="color:#ce5c00"><strong>,</strong></span><span style="color:#0000cf">40.75</span>]<span style="color:#ce5c00"><strong>,</strong></span>[<span style="color:#ce5c00"><strong>-</strong></span><span style="color:#0000cf">105.17</span><span style="color:#ce5c00"><strong>,</strong></span><span style="color:#0000cf">40.56</span>]])<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Filter your dataset from the entire collection to the year of interest and extent</em></span></span>
<span style="color:inherit"><span style="color:#8f5902"><em>// and add the filterBounds function, moving the semicolon to the end of the statement.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> naip2011 <span style="color:#ce5c00"><strong>=</strong></span> NAIP</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterDate</span>(<span style="color:#4e9a06">"2011-01-01"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2011-10-31"</span>)</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterBounds</span>(bounds)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Define visualization parameters.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsFalse <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'N'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsTrue <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'B'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Add 2011 imagery to the map with false color and true color composites.</em></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsFalse<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2011_false"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsTrue<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2011_true"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">centerObject</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#0000cf">11</span>)<span style="color:#ce5c00"><strong>;</strong></span></span></code></span></span></span></span>

3.5把所有东西放在一起

利用我们在本模块中可视化的 NAIP 数据，我们已准备好使用 GEE 执行此介绍性分析。将额外的 NAIP 数据子集添加到我们的代码中，我们可以直观地比较 High Park Fire 边界内外的植被再生情况。运行以下代码，我们发现虽然真彩色图像有些帮助，但假彩色图像（如下所示）使我们能够轻松地区分低光合活性区域（较高烧伤严重程度）和光合活性相对不变的区域（严重程度低或未燃烧）。

<span style="color:#333333"><span style="background-color:#ffffff"><span style="color:#333333"><span style="background-color:#f8f8f8"><code><span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> naip2013 <span style="color:#ce5c00"><strong>=</strong></span> NAIP</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterDate</span>(<span style="color:#4e9a06">"2013-01-01"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2013-12-31"</span>)</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterBounds</span>(bounds)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// add 2013 imagery to the map with false color and true color composites</em></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2013<span style="color:#ce5c00"><strong>,</strong></span> visParamsFalse<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2013_false"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2013<span style="color:#ce5c00"><strong>,</strong></span> visParamsTrue<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2013_true"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span></code></span></span></span></span>

2011 年（左上）和 2013 年（右上）的真彩色 NAIP 图像与 2011 年（左下）和 2013 年（右下）的假彩色图像相比。
 

但 NAIP 图像的实用性不仅限于大规模分析。放大到 High Park Fire 的较小区域（如下所示），我们可以看到由于数据集的高分辨率，可以在非常小的范围内评估烧伤程度。

仔细查看通过 NAIP 图像可获得的详细程度。在 2011 年的图像（上）中可以清楚地看到个别树木，而在 2013 年的图像（下）中仍然存在那些在火灾中幸存下来的树木。

<span style="color:#333333"><span style="background-color:#ffffff"><span style="color:#333333"><span style="background-color:#f8f8f8"><code><span style="color:inherit"><span style="color:#8f5902"><em>// Call in NAIP imagery as an image collection.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> NAIP <span style="color:#ce5c00"><strong>=</strong></span> ee<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">ImageCollection</span>(<span style="color:#4e9a06">"USDA/NAIP/DOQQ"</span>)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Enter the desired coordinates for the upper left and lower right corners of your study area.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> bounds <span style="color:#ce5c00"><strong>=</strong></span> ee<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#c4a000">Geometry</span><span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">Rectangle</span>([[<span style="color:#ce5c00"><strong>-</strong></span><span style="color:#0000cf">105.53</span><span style="color:#ce5c00"><strong>,</strong></span><span style="color:#0000cf">40.75</span>]<span style="color:#ce5c00"><strong>,</strong></span>[<span style="color:#ce5c00"><strong>-</strong></span><span style="color:#0000cf">105.17</span><span style="color:#ce5c00"><strong>,</strong></span><span style="color:#0000cf">40.56</span>]])<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Filter your dataset from the entire collection to the year of interest and extent.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> naip2011 <span style="color:#ce5c00"><strong>=</strong></span> NAIP</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterDate</span>(<span style="color:#4e9a06">"2011-01-01"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2011-12-31"</span>)</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterBounds</span>(bounds)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Define visualization parameters.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsFalse <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'N'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> visParamsTrue <span style="color:#ce5c00"><strong>=</strong></span> {<span style="color:#204a87">bands</span><span style="color:#ce5c00"><strong>:</strong></span>[<span style="color:#4e9a06">'R'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'G'</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">'B'</span>]}<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Add 2011 imagery to the map with false color and true color composites.</em></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsFalse<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2011_false"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span>visParamsTrue<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2011_true"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">centerObject</span>(naip2011<span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#0000cf">11</span>)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Add 2013 imagery to the map with false color and true color composites.</em></span></span>
<span style="color:inherit"><span style="color:#204a87"><strong>var</strong></span> naip2013 <span style="color:#ce5c00"><strong>=</strong></span> NAIP</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterDate</span>(<span style="color:#4e9a06">"2013-01-01"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#4e9a06">"2013-12-31"</span>)</span>
<span style="color:inherit">  <span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">filterBounds</span>(bounds)<span style="color:#ce5c00"><strong>;</strong></span></span><span style="color:inherit"><span style="color:#8f5902"><em>// Add 2013 imagery to the map with false color and true color composites.</em></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2013<span style="color:#ce5c00"><strong>,</strong></span>visParamsFalse<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2013_false"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span>
<span style="color:inherit">Map<span style="color:#ce5c00"><strong>.</strong></span><span style="color:#000000">addLayer</span>(naip2013<span style="color:#ce5c00"><strong>,</strong></span>visParamsTrue<span style="color:#ce5c00"><strong>,</strong></span><span style="color:#4e9a06">"2013_true"</span><span style="color:#ce5c00"><strong>,</strong></span> <span style="color:#204a87"><strong>false</strong></span> )<span style="color:#ce5c00"><strong>;</strong></span></span></code></span></span></span></span>