图形缓冲
==========================

1.描述
------------

在输入要素周围某一指定距离内创建缓冲区多边形。在要素周围生成缓冲区时，多种制图形状对缓冲区末端（端头）和拐角（连接）可用

2.使用限制
----------------

3.算子id
----------------
igis.gis.analysis.proximity.graphicBuffer

4.参数列表
------------------------------


+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
| 参数类型 | 参数名称                 | 参数关键字                   | 必要性 | 参数说明                                                                                                                                                                                                 | 数据类型 |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
| 输入参数 | url                      | 数据源地址                   | Y      | 数据源地址                                                                                                                                                                                               | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | in_features              | 待缓冲要素                   | Y      | 要进行缓冲的输入点、线或面要素                                                                                                                                                                           | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | buffer_distance_or_field | 缓冲距离                     | Y      | 与要缓冲的输入要素之间的距离。该距离可以用表示线性距离的某个值来指定，也可以用输入要素中的某个字段（包含用来对每个要素进行缓冲的距离）来指定                                                             | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | line_caps                | 将要进行缓冲的输入要素的端头 | N      | 将要进行缓冲的输入要素的端头（末端）                                                                                                                                                                     | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | line_joins               | 缓冲形状                     | N      | 两条线段连接拐角处的缓冲区的形状。该参数仅支持线和面要素                                                                                                                                                 | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | miter_limit              |                              | N      | 当线段相交呈锐角且指定了 MITER 的 line_joins 时，可使用该参数来控制缓冲输出的锐角如何逐渐变为点。某些情况下，当使用MITERline_joins时，两条线连接形成的外角会非常大。这可能会导致拐角点的延伸超出您的预期 | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
|          | max_deviation            |                              | N      | 输出缓冲区面边界将从实际理想缓冲区边界偏移的最大距离。实际缓冲区边界为曲线，输出面边界为增密折线。可以使用此参数来控制面边界与实际缓冲区边界的近似程度                                                   | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+
| 输出参数 | out_feature_class        | 结果图层                     | Y      | 所创建的要素类，并且结果将写入其中。                                                                                                                                                                     | String   |
+----------+--------------------------+------------------------------+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+


5.配置面板
--------------------

.. image:: ../../../_static/images/graphicbuffer_panel.jpg
   :width: 300px

6.调用示例
------------------
.. code::
  
    {
      "params": {
        "url":"kudu://172.20.20.11:7051/geomesa_mc_test",
        "in_features":"buffer_test",
        "buffer_distance_or_field":"20 Meters",
        "out_feature_class":"buffer_graphicbuffer",
        "line_caps":"ROUND",
        "line_joins":"ROUND"
      },
      "identifier":"igis.gis.analysis.proximity.graphicBuffer"
    }