SPATIALFILTER

Used in

Servers

Image Query Feature Extract

Parent elements

Syntax

<SPATIALFILTER	Attribute Description Table
(r)relation="area_intersection \| envelope_intersection" > (r)<ENVELOPE... /> [Or] (r)<MULTIPOINT... /> [Or] (r)<POLYGON... /> [Or] (r)<POLYLINE... /> [Or] <BUFFER... /> </SPATIALFILTER >
(r): Attribute or child element is required.

Description

A spatial filter defines the envelope for a spatial query. The envelope can be a rectangle, point, line, polygon, or buffer.

Restrictions

One ENVELOPE, POLYLINE, POLYGON, or MULTIPOINT element is required. Only one of these elements can be used.
Using MULTIPOINT as a filter against a point or line layer will yield no results. Instead, a small envelope should be generated around this point. The envelope can then be used as the filter. Similarly, POLYLINE used against a point will yield no results. If desired, an envelope can be generated around the line for use as a filter.
When using relation="envelope_intersection" on ArcSDE layers, no features are returned when
- MULTIPOINT is used.
- a POLYLINE where all x-coordinates or all y-coordinates are the same.
The reason is that all points and some lines do not have an associated envelope and hence cannot be used to query features using "envelope_intersection". Use relation="area_intersection" instead.

Notes

When "area_intersection" is used with relation, all features that partially or fully fall within the area of the filter are selected. This operation can take some time. To speed up processing, "envelope_intersection" can be used instead. This method checks to see if the bounding box of the filter overlaps any bounding boxes of the features in the layer. A much quicker search results, but the features found could fall outside the area of the filter. In the examples below, an oval shape is used as the filter. When "envelope_intersection" is used, features outside the filter can be selected even though they are far outside the filter.

Shape of spatial filter to select points	Points selected when relation="area_intersection"	Points selected when relation="envelope_intersection"
Shape of spatial filter to select polygons	No polygons are selected when relation="area_intersection"	Polygon is selected when relation="envelope_intersection"

In general, it is recommended to use "area_intersection" to be certain you are retrieving the correct features. The value "envelope_intersection" should only be used in customized environments where you plan to retrieve a subset of features on which to run a second query using "area_intersection".

Attribute Descriptions for SPATIALFILTER

Attribute	Usage
relation	Describes spatial relation. It is recommended to use "area_intersection". See Notes section for more details.

Examples for SPATIALFILTER

Example 1: Note in this example that the DATASET fromlayer is "Countries". This refers to the LAYER id in the map configuration file, not the LAYER name.

<?xml version="1.0" encoding="UTF-8"?>
<ARCXML version="1.1">
<REQUEST>
  <GET_IMAGE>
    <PROPERTIES>
      <ENVELOPE minx="-180" miny="-90" maxx="180" maxy="90" />
      <IMAGESIZE width="643" height="502" />
    </PROPERTIES>
    <LAYER type="featureclass" name="select layer" visible="true" id="300">
      <DATASET fromlayer="Countries" />
      <SPATIALQUERY>
        <SPATIALFILTER relation="area_intersection">
          <ENVELOPE maxy="30" maxx="30" miny="0" minx="0" />
        </SPATIALFILTER>
      </SPATIALQUERY>
      <SIMPLERENDERER>
        <SIMPLEPOLYGONSYMBOL fillcolor="255,255,255" filltype="cross" />
      </SIMPLERENDERER>
    </LAYER>
  </GET_IMAGE>
</REQUEST>
</ARCXML>