Arrow labels not rendered correctly

Question

Geoserver SLD:

  <sld:LineSymbolizer>
    <sld:Stroke>
      <sld:CssParameter name="stroke">
        <ogc:PropertyName>geo_color</ogc:PropertyName>
      </sld:CssParameter>
      <sld:CssParameter name="stroke-width">2</sld:CssParameter>
    </sld:Stroke>
  </sld:LineSymbolizer>
  <TextSymbolizer>
    <Label>
      <ogc:Literal>&#x227b;</ogc:Literal>
    </Label>
    <Font>
      <CssParameter name="font-family">Lucida Sans</CssParameter>
      <CssParameter name="font-size">20</CssParameter>
    </Font>
    <LabelPlacement>
    <LinePlacement>
    <PerpendicularOffset>0</PerpendicularOffset>
    </LinePlacement>
    </LabelPlacement>
    <Fill>
      <CssParameter name="fill">
        <ogc:PropertyName>geo_color</ogc:PropertyName>
      </CssParameter>
    </Fill>
    <VendorOption name="followLine">true</VendorOption>
    <VendorOption name="forceLeftToRight">false</VendorOption>
    <VendorOption name="conflictResolution">false</VendorOption>
  </TextSymbolizer>

I have the above style set for a WMS layer containing line strings. For most zoom levels the direction arrow aligns properly with its corresponding line. But on zooming out beyond a point, the arrows seem to be displaced away from their respective lines. Shown here:

I am fairly sure that this has to do something with VendorOption parameters but unable to put a finger on it.

Answer 1

You can edit config.yaml file in geoserver to render the arrow....

#===========================================================================
# allowed DPIs
#===========================================================================
dpis:
  - 254
  - 300

#===========================================================================
# allowed Formats
#===========================================================================
# '*' means any formats
formats: ['*']

#===========================================================================
# the allowed scales
#===========================================================================
scales:
  - 188
  - 375
  - 750
  - 1500
  - 3000
  - 6000
  - 12000
  - 24000
  - 48000
  - 96000
  - 192000
  - 384000
  - 768000
  - 1536000
  - 3072000
  - 6144000
  - 12288000


#===========================================================================
# the list of allowed hosts
#===========================================================================


# the default fileName for the files downloaded from the servlet
outputFilename: Export Map

layouts:
  #===========================================================================
  A4 portrait:
  #===========================================================================
    # override the default outputFileName defined above
#    outputFilename: A4_Layout
    mainPage:
      rotation: true
      pageSize: A4
      marginLeft: 40
      marginRight: 40
      marginTop: 20
      marginBottom: 20
      header:
        height: 50
        items:
          - !text
            font: Helvetica
            fontSize: 18
            align: center           
            text: '${mapTitle}' 

      items:
        - !table
            config:
               borderWidth: 1
               borderColor: black
               borderWidthLeft: 1
               borderWidthRight: 1
               borderWidthTop: 1
               borderWidthBottom: 1
               borderColorLeft: black
               borderColorRight:black
               borderColorTop: black
               borderColorBottom: black
            items:
                - !map
                  spacingAfter: 0
                  width: 515
                  border: true
                  borderWidthLeft: 2
                  borderColorLeft: black
                  height: 500
                  align: left
        - !table
            absoluteX: 405
            absoluteY: 772
            width: 150
            height:  100
            config:
               borderWidth: 1
               borderColor: black
               borderWidthLeft: 1
               borderWidthRight: 1
               borderWidthTop: 1
               borderWidthBottom: 1
               borderColorLeft: black
               borderColorRight:black
               borderColorTop: black
               borderColorBottom: black
            items:
               - !image
                 rotation: '${rotation}'
                 maxWidth: 50
                 maxHeight: 50
                 url: 'http://localhost:8080/geoserver/www/images/2.png'
                 align: RIGHT
                 vertAlign: MIDDLE
               - !text
                  font: Helvetica
                  fontSize: 6
                  align: LEFT
                  vertAlign: MIDDLE
                  text: 'scale:   1 : ${scale} ' 
        - !table
            config:
               borderWidth: 1
               borderColor: black
               borderWidthLeft: 1
               borderWidthRight: 1
               borderWidthTop: 1
               borderWidthBottom: 1
               borderColorLeft: black
               borderColorRight:black
               borderColorTop: black
               borderColorBottom: black
            items:
                - !legends
                   maxIconWidth: 0
                   maxIconHeight: 0
                   classIndentation: 0
                   layerSpace: 3
                   classSpace: 2
                   backgroundColor: #FFFFFF
                   layerFont: Helvetica
                   layerFontSize: 8
                   classFont: Helvetica
                   classFontSize: 6
                   textMaxWidth: 5
                   textMaxHeight: 5
                   iconMaxHeight: 5
                   inLine: false
                   fontEncoding: Cp1252
                   columnMargin: 3
        - !text
          text: '${mapComment}'
          spacingAfter: 25
      footer:
        height: 20
        items:
          - !columns
            items:
              - !text    
                fontSize: 8
                fontColor:#7D7877               
                align: left


              - !text   
                fontSize: 8           
                align: center
                text: '${pageNum}'
              - !text
                font: Helvetica
                fontSize: 8
                align: right            
                text: '${now MM.dd.yyyy}'

Printing a map in geoserver using config.yaml file...