How do I add an inner halo style?

Background

There may be times when you need to go beyond the styling of polygons by single or class based values. To achieve this you need to play with the SLD editor. 

In the example below you will find information on creating an inner halo styling effect that is ideal of planning applications or planning policy layers. 

Examples of planning applications being styled with an inner halo. 

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Warning! 

Playing with SLD editor requires a degree of familiarity with XML and SLD tags. We suggest having a look at introduction to SLDs in the first instance, and then progressing onto these examples.

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SLD notes:

The SLD file will produce an inner halo in progressively faded (by opacity) red (#ff0000) lines.

There are two scale thresholds set as well (see line 10/11, and line 54/55). 

If you want to change the colour from red, then do a find and replace on #ff0000

Key components of the SLD - 

1. <CssParameter name="stroke">#ff0000</CssParameter> -- sets the colour of the line
2. <CssParameter name="stroke-width">5</CssParameter> -- sets the width of the line
3. <CssParameter name="stroke-opacity">0.25</CssParameter> -- set the opacity of the line
4. <PerpendicularOffset>-8.0</PerpendicularOffset> -- set the offset value

SLD code:

1. <?xml version="1.0"?>
2. <StyledLayerDescriptor version="1.0.0" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.0.0/StyledLayerDescriptor.xsd" xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
3. <NamedLayer>
4. <Name>Planning Applications</Name>
5. <UserStyle>
6. <Title/>
7. <Abstract/>
8. <FeatureTypeStyle>
9. <Rule>
10. <MinScaleDenominator>1</MinScaleDenominator>
11. <MaxScaleDenominator>1250</MaxScaleDenominator>
12. <LineSymbolizer>
13. <Stroke>
14. <CssParameter name="stroke">#ff0000</CssParameter>
15. <CssParameter name="stroke-width">5</CssParameter>
16. <CssParameter name="stroke-opacity">0.25</CssParameter>
17. <CssParameter name="stroke-linecap">bevel</CssParameter>
18. </Stroke>
19. <PerpendicularOffset>-8.0</PerpendicularOffset>
20. </LineSymbolizer>
21. <LineSymbolizer>
22. <Stroke>
23. <CssParameter name="stroke">#ff0000</CssParameter>
24. <CssParameter name="stroke-width">5</CssParameter>
25. <CssParameter name="stroke-opacity">0.5</CssParameter>
26. <CssParameter name="stroke-linecap">bevel</CssParameter>
27. </Stroke>
28. <PerpendicularOffset>-5.0</PerpendicularOffset>
29. </LineSymbolizer>
30. <LineSymbolizer>
31. <Stroke>
32. <CssParameter name="stroke">#ff0000</CssParameter>
33. <CssParameter name="stroke-width">8</CssParameter>
34. <CssParameter name="stroke-opacity">0.7</CssParameter>
35. <CssParameter name="stroke-linecap">bevel</CssParameter>
36. </Stroke>
37. <PerpendicularOffset>-2.5</PerpendicularOffset>
38. </LineSymbolizer>
39. <PolygonSymbolizer>
40. <Fill>
41. <CssParameter name="fill">#ff0000</CssParameter>
42. <CssParameter name="opacity">0.05</CssParameter>
43. </Fill>
44. </PolygonSymbolizer>
45. <PolygonSymbolizer>
46. <Stroke>
47. <CssParameter name="stroke">#000000</CssParameter>
48. <CssParameter name="stroke-width">2</CssParameter>
49. <CssParameter name="stroke-linejoin">bevel</CssParameter>
50. </Stroke>
51. </PolygonSymbolizer>
52. </Rule>
53. <Rule>
54. <MinScaleDenominator>1251</MinScaleDenominator>
55. <MaxScaleDenominator>125000</MaxScaleDenominator>
56. <LineSymbolizer>
57. <Stroke>
58. <CssParameter name="stroke">#ff0000</CssParameter>
59. <CssParameter name="stroke-width">6</CssParameter>
60. <CssParameter name="stroke-opacity">0.15</CssParameter>
61. <CssParameter name="stroke-linecap">bevel</CssParameter>
62. </Stroke>
63. <PerpendicularOffset>-1.5</PerpendicularOffset>
64. </LineSymbolizer>
65. <LineSymbolizer>
66. <Stroke>
67. <CssParameter name="stroke">#ff0000</CssParameter>
68. <CssParameter name="stroke-width">4</CssParameter>
69. <CssParameter name="stroke-opacity">0.25</CssParameter>
70. <CssParameter name="stroke-linecap">bevel</CssParameter>
71. </Stroke>
72. <PerpendicularOffset>-1.0</PerpendicularOffset>
73. </LineSymbolizer>
74. <PolygonSymbolizer>
75. <Fill>
76. <CssParameter name="fill">#ff0000</CssParameter>
77. <CssParameter name="opacity">0.05</CssParameter>
78. </Fill>
79. </PolygonSymbolizer>
80. <PolygonSymbolizer>
81. <Stroke>
82. <CssParameter name="stroke">#000000</CssParameter>
83. <CssParameter name="stroke-width">.75</CssParameter>
84. <CssParameter name="stroke-linejoin">bevel</CssParameter>
85. </Stroke>
86. </PolygonSymbolizer>
87. </Rule>
88. </FeatureTypeStyle>
89. </UserStyle>
90. </NamedLayer>
91. </StyledLayerDescriptor>

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