Description:

Builds a buffer region around selected features.

Restrictions:

• SPATIALQUERY used in BUFFER cannot contain another BUFFER inside.
• When using a target layer that is the same layer as the buffer layer, the resulting buffer will be different when using an ArcMap Image Service compared to Image or Feature Services. The following ArcXML shows the syntax for a buffer layer and a target layer. The buffer and target layer are the same (cities). Note that this is only an issue when the buffer layer and target layer are the same.
  
  <!-- Set the buffer around the selected feature (Belgium) -->
  <LAYER type="featureclass" name="theBuffer" visible="true" id="buffer">
    <DATASET fromlayer="countries"/>
    <SPATIALQUERY>
      <BUFFER distance="100" bufferunits="miles" />
      <SPATIALFILTER relation="area_intersection">
        <ENVELOPE minx="4.68" miny="50.34" maxx="5.46" maxy="50.86"/>
      </SPATIALFILTER>
    </SPATIALQUERY>
    <SIMPLERENDERER>
      <SIMPLEPOLYGONSYMBOL fillcolor="100,100,100" filltransparency="0.5" />
    </SIMPLERENDERER>
  </LAYER>
  
  <!-- Select features in the target layer based on which countries fall inside the buffer -->
  <LAYER type="featureclass" name="theBufferTarget" visible="true" id="buffertarget">
    <DATASET fromlayer="countries"/>
    <SPATIALQUERY>
      <BUFFER distance="100" bufferunits="miles">
        <TARGETLAYER id="countries"/>
      </BUFFER>
      <SPATIALFILTER relation="area_intersection">
        <ENVELOPE minx="4.68" miny="50.34" maxx="5.46" maxy="50.86"/>
      </SPATIALFILTER>
    </SPATIALQUERY>
    <SIMPLERENDERER>
      <SIMPLEPOLYGONSYMBOL fillcolor="255,120,120" filltype="solid" />
    </SIMPLERENDERER>
  </LAYER>
  
  

  When using the Image Server, a feature is selected and a buffer is created around the feature. Next, the target layer is applied. All features that fall within the buffer are selected. In this example, Belgium is selected and buffered 100 miles. The resulting buffer is around Belgium only. Since the countries layer is also the target layer, all surrounding countries that fall within the buffer are highlighted.

  When using the ArcMap Server, a feature is selected and a buffer is created around the feature. Next, the target layer is applied. All features that fall within the buffer are selected. The buffer is then applied to these features as well. In this example, Belgium is selected and buffered 100 miles. All countries within the 100-mile buffer are selected. The final 100-mile buffer is generated around all selected countries. The buffer in this example is represented by the diagonal lines.

  
  

Notes:

• BUFFER can be used three ways:
  
  

  	To buffer a region around one or more selected features, use BUFFER inside a SPATIALQUERY. In this example, the Colorado River is buffered. <LAYER type="featureclass" name="theRiverBuffer" id="RivBuf">   <DATASET fromlayer="Rivers" />   <SPATIALQUERY where="NAME='Colorado'">     <BUFFER distance="80" bufferunits="MILES" />   </SPATIALQUERY>   <SIMPLERENDERER>     <SIMPLEPOLYGONSYMBOL fillcolor="255,255,0" filltransparency=".3" boundarycolor="255,255,0" boundarywidth="2" />   </SIMPLERENDERER> </LAYER>
  	To select features from the same or another layer that fall within the buffer region, use TARGETLAYER as a child element. In this example, cities within 80 miles of the Colorado River are selected. (The buffer in the picture is shown for reference. With this request, only selected cities would display. To highlight the cities and show the buffer, both the following and preceding LAYER examples must be used in a request.) <LAYER type="featureclass" name="theRiverBuffer" id="RivBuf">   <DATASET fromlayer="Rivers" />   <SPATIALQUERY where="NAME='Colorado'">     <BUFFER distance="80" bufferunits="MILES" >       <TARGETLAYER id="Cities" />     </BUFFER>   </SPATIALQUERY>   <SIMPLERENDERER>     <SIMPLEMARKERSYMBOL color="255,255,0" width="6" />   </SIMPLERENDERER> </LAYER>
  	To use a buffer as a selection tool. BUFFER is used around a defined filter within SPATIALFILTER. In this example, BUFFER is used to buffer around an envelope. The inner yellow box is the original envelope. The outer yellow box is the buffer filter. Note that these boxes would not normally display; only the selected items within the filter. <LAYER type="featureclass" name="theEvelopeBuffer" id="EnvBuf" >   <DATASET fromlayer="Cities" />   <SPATIALQUERY where="POPULATION > 1000000" >     <SPATIALFILTER relation="envelope_intersection">       <ENVELOPE minx="-119" miny="32" maxx="-113" maxy="35" />       <BUFFER distance="100" bufferunits="MILES" />     </SPATIALFILTER>   </SPATIALQUERY>   <SIMPLERENDERER>     <SIMPLEMARKERSYMBOL color="255,255,0" width="6" />   </SIMPLERENDERER> </LAYER>

  
  
• In a GET_FEATURES request, when SPATIALQUERY is a parent element to BUFFER and subfields is included, the field #SHAPE# or #ALL# must be included in the subfields list.
• A buffer distance of 0 can be used on polygon features. If a buffer distance of 0 is used with line or point features, no data is returned.
• Buffer results may be inaccurate on unprojected data. It is recommended to project data before applying a buffer.

Attribute Descriptions for BUFFER:

Examples for BUFFER: