LAYERINFO

Used in

Servers

Image Query Feature Extract Geocode

Parent elements

Syntax

<LAYERINFO	Attribute Description Table
*(r)id="string"* maxscale="string" minscale="string" name="string" type="featureclass \| image \| acetate" visible="true \| false" > When parent element is LAYERINFO and type is acetate: (m)<OBJECT... /> [Image Services only] When parent element is LAYERINFO and type is featureclass for Image or Feature Services: (r)<FCLASS... /> <EXTENSION... /> <GROUPRENDERER... /> <SCALEDEPENDENTRENDERER... /> <SIMPLELABELRENDERER... /> <SIMPLERENDERER... /> <VALUEMAPLABELRENDERER... /> <VALUEMAPRENDERER... /> When parent element is LAYERINFO and type is image: <ENVELOPE... /> <RASTER_RENDERER... /> [Image Services only] </LAYERINFO >
(r): Attribute or child element is required. (m): Child element can be used multiple times.

Description

Defines layer information such as ID and name, minimum and maximum scale, layer type, and whether the layer is visible.

Notes

When GET_SERVICE_INFO relativescale="false", or relativescale is not included in the request, scales in LAYERINFO are calculated based on the number of map units per pixel. In requests and the map configuration file, scales can be set using a relative scale ratio such as 1:24000. In this example, 1 meter equals 24000 meters or 1 inch equals 24000 inches.

Map units per pixel refers to the number of meters, feet, or decimal degrees represented by one pixel in a map. To convert from a relative scale to map units per pixel, the size of a pixel must first be calculated. The formula for finding the number of meters in a pixel is 0.0254 / dpi where:
- The value 0.0254 is the number of meters in an inch.
- Dpi is the dpi set in the service or request. If no dpi is set in the ArcIMS service or request, the dpi is assumed to be 96.
As an example of calculating pixel size, if the dpi is 96, the pixel size is 0.0254 / 96 or 0.000265 m.

Once the pixel size is known, the relative scale can be converted to map units per pixel:
1. If the scale is in meters. To calculate the number of meters per pixel, take the relative scale and multiply by the pixel size (0.000265). For example, if the relative scale is 1:24000, then the number of meters per pixel is 24000 * 0.000265, or 6.36 meters.
2. If the scale is in feet. Do the calculation for meters (#1). Multiply the result by 3.28 (the number of feet in a meter). For example, if the number of meters per pixel is 6.36, the number of feet per pixel is 6.36 * 3.28, or 20.86 feet.
3. If the scale is in decimal degrees. For these calculations, the Earth is assumed to be an exact sphere with a circumference of 40030.174 km. One degree is 111.195 km (40030.174/360 degrees) or 111195 meters. To calculate the number of degrees, first do the calculation for meters (#1). Next, divide the result by 111195. For example, if the number of meters per pixel is 6.36, the number of degrees per pixel is 6.36 / 111195, or 0.0000571968.

Attribute Descriptions for LAYERINFO

Attribute	Usage
id	Reference to unique layer ID as defined in map configuration file.
maxscale	Maximum scale to display map. Does not apply unless maxscale is set in the service. When scale values are returned as a relative scale, values are not rounded when the map is in decimal degrees.
minscale	Minimum scale to display map. Does not apply unless minscale is set in the service. When scale values are returned as a relative scale, values are not rounded when the map is in decimal degrees.
name	Layer name as defined in map configuration file.
type	Shows type of layer as defined in map configuration file.
visible	Specifies whether or not layer is visible.

Examples for LAYERINFO

<?xml version="1.0" encoding="UTF-8"?>
<ARCXML version="1.1">
  <RESPONSE>
    <SERVICEINFO>
      <ENVIRONMENT>
        <LOCALE language="en" country="US" />
        <UIFONT name="Arial" color="0,0,0" size="12" style="regular" />
        <SEPARATORS cs=" " ts=";"/>
        <CAPABILITIES forbidden="" disabledtypes=""/>
        <SCREEN dpi="96"/>
        <IMAGELIMIT pixelcount="1048576" />
      </ENVIRONMENT>
      <PROPERTIES>
        <FEATURECOORDSYS id="4326"/>
        <FILTERCOORDSYS id="4326"/>
        <ENVELOPE minx="-180" miny="-90" maxx="180" maxy="90" name="Initial_Extent" />
        <MAPUNITS units="decimal_degrees" />
      </PROPERTIES>
      <LAYERINFO type="featureclass" visible="true" name="Countries" id="1">
        <FCLASS type="polygon">
          <FIELD name="AREA" type="8" size="12" precision="3" />
          <FIELD name="NAME" type="12" size="40" precision="0" />
          <FIELD name="ABBREVNAME" type="12" size="12" precision="0" />
          <FIELD name="FIPS_CODE" type="12" size="2" precision="0" />
          <FIELD name="WB_CNTRY" type="12" size="3" precision="0" />
          <FIELD name="HYPERLINK" type="12" size="60" precision="0" />
          <FIELD name="#SHAPE#" type="-98" size="0" precision="0" />
          <FIELD name="#ID#" type="-99" size="16" precision="0" />
        </FCLASS>
      </LAYERINFO>
      <LAYERINFO name="NorthArrow" visible="true" id="NorthArrow"<
        <OBJECT units="pixel">
          <NORTHARROW type="4" coords="20 30" shadow="32,32,32" size="15" angle="0" antialiasing="true" overlap="false" />
        </OBJECT>
      </LAYERINFO>
    </SERVICEINFO>
  </RESPONSE>
</ARCXML>