1. Creating stunning maps
with GeoServer
Mastering SLD and CSS
Ing. Andrea Aime
GeoSolutions

2. GeoSolutions
 Founded in Italy in late 2006
 Expertise
• Image Processing, GeoSpatial Data Fusion
• Java, Java Enterprise, C++, Python
• JPEG2000, JPIP, Advanced 2D visualization
 Supporting/Developing FOSS4G projects
 GeoServer, MapStore
 GeoNetwork, GeoNode, Ckan
 Clients
 Public Agencies
 Private Companies
 http://www.geo-solutions.it
FOSS4G 2017, Boston
August 14th-19th 2017

3. SLD vs CSS
 Styled Layer Descriptor
 OGC standard
 XML based, verbose, hard to hand edit
 Only showing relevant bits of the SLD
 GeoCSS
 CSS with extensions for map rendering
 Simple, Compact, designed for human beings
 Not a standard (several incompatible variants for
mapping, GeoServer one has nothing to do with
CartoDB/MapBox one)
FOSS4G 2017, Boston
August 14th-19th 2017

4. CSS features
 Familiar for web developers
 Compact syntax
 Symbolization triggered by “key” properties
(stroke, fill, mark, label, channel-selection)
 CQL based filtering
 Cascading keeps complex styling compact (you
just express the overrides to the base)
 Interactive editor for productive style
development
FOSS4G 2017, Boston
August 14th-19th 2017

5. GeoCSS in a nutshell
• Filter by attribute/env variable in CQL
• Filter by scale
• Set properties to control symbolization
• Key properties activate certain symbolization:
– mark/fill/stroke/label/raster-channels
FOSS4G 2017, Boston
August 14th-19th 2017
[admin_level < 2][@sd < 1M][@sd > 100k] {
label: name;
font-family: ‘Noto Sans’;
…
/* this is nested rule */
[special = true][@sd < 500k] {
font-weight: bold;
…
}
}

6. SLD equivalents
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:Rule>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>admin_level</ogc:PropertyName>
<ogc:Literal>2</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<sld:MinScaleDenominator>100000</sld:MinScaleDenominator>
<sld:MaxScaleDenominator>1000000</sld:MaxScaleDenominator>
<sld:TextSymbolizer>
<sld:Label>
<ogc:PropertyName>name</ogc:PropertyName>
</sld:Label>
<sld:Font>
<sld:CssParameter name="font-family">
Noto Sans
</sld:CssParameter>
<sld:CssParameter name="font-size">10
...
</sld:TextSymbolizer>
<!–- Override would require a separate rule specifying everything again -->
</sld:Rule>
Filter
Scale
dependency
Symbolizers
and their
properties

7. Scale dependencies
FOSS4G 2017, Boston
August 14th-19th 2017

8. Types of Scale dependency
 Decide whether to symbolize based on the scale or not
 E.g., at lower scales/lower zoom levels do not show buildings
 Symbolize in a different way depending on the scale
 E.g., different thickness based on the current zoom
FOSS4G 2017, Boston
August 14th-19th 2017

9. Expressing scale dependency filters
 SLD:
 <MinScaleDenominator>
 <MaxScaleDenominator>
 CSS
 Legacy: [@scale > 10000000]
 GeoServer 2.12+: [@sd > 1M]
 More compact variable, more correct (it’s a scale
denominator, not a scale!)
 Compact expression of large numbers makes them readable
at a glance, e.g., 100k, 1M
FOSS4G 2017, Boston
August 14th-19th 2017

10. Unit of Measure
FOSS4G 2017, Boston
August 14th-19th 2017
 Useful if you have real world measures of line
thicknesses and the like
<LineSymbolizer uom="http://www.opengeospatial.org/se/units/metre">
<Stroke>
<CssParameter name="stroke">#0000FF</CssParameter>
<CssParameter name="stroke-width">5</CssParameter>
</Stroke>
</LineSymbolizer>
* {
stroke: blue;
stroke-width: 5m;
}

11. Transformation functions
FOSS4G 2017, Boston
August 14th-19th 2017
 OSM like, setting a different value depending on
the current scale/zoom level
 Not a linear scale mind
[class = 'highway’
and type in ('motorway’,
'motorway_link’)]
[@sd < 25M] {
stroke: #e66e89;
stroke-width: categorize(@sd,
2, 400k,
1.9, 800k,
1.4, 1.5M,
1, 3M,
0.8, 6M,
0.5);
…
 Less than 400k  2px
 [400k, 800k]  1.9px
 [800k, 1.5M]  1.4px
 [1.5M, 3M]  1
 [3M, 6M]  0.8
 Above 6M -> 0.5

12. Transformation functions in SLD
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:LineSymbolizer>
<sld:Stroke>
<sld:CssParameter name="stroke">#e66e89</sld:CssParameter>
<sld:CssParameter name="stroke-width">
<ogc:Function name="Categorize">
<ogc:Function name="env">
<ogc:Literal>wms_scale_denominator</ogc:Literal>
</ogc:Function>
<ogc:Literal>2</ogc:Literal>
<ogc:Literal>400000</ogc:Literal>
<ogc:Literal>1.9</ogc:Literal>
<ogc:Literal>800000</ogc:Literal>
<ogc:Literal>1.4</ogc:Literal>
<ogc:Literal>1500000</ogc:Literal>
<ogc:Literal>1</ogc:Literal>
<ogc:Literal>3000000</ogc:Literal>
<ogc:Literal>0.8</ogc:Literal>
<ogc:Literal>6000000</ogc:Literal>
<ogc:Literal>0.5</ogc:Literal>
</ogc:Function>
</sld:CssParameter>
</sld:Stroke>
</sld:LineSymbolizer>

13. Point styling
FOSS4G 2017, Boston
August 14th-19th 2017

14. Simple symbol
FOSS4G 2017, Boston
August 14th-19th 2017
[type = 'alpine_hut'][@sd < 100k] {
mark: url('symbols/alpinehut.p.16.png');
}
<sld:Rule>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>type</ogc:PropertyName>
<ogc:Literal>alpine_hut</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<sld:MaxScaleDenominator>100000.0</sld:MaxScaleDenominator>
<sld:PointSymbolizer>
<sld:Graphic>
<sld:ExternalGraphic>
<sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:type="simple"
xlink:href="symbols/alpinehut.p.16.png"/>
<sld:Format>image/png</sld:Format>
</sld:ExternalGraphic>
</sld:Graphic>
</sld:PointSymbolizer>
</sld:Rule>

15. Marks (SVG in this case)
FOSS4G 2017, Boston
August 14th-19th 2017
[type = 'bank'][@sd < 6k] {
mark: symbol('file://symbols/bank.svg');
:mark { fill: #734a08 };
mark-size: 14;
}
<sld:Rule>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>type</ogc:PropertyName>
<ogc:Literal>bank</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<sld:MaxScaleDenominator>6000.0</sld:MaxScaleDenominator>
<sld:PointSymbolizer>
<sld:Graphic>
<sld:Mark>
<sld:WellKnownName>file://symbols/bank.svg</sld:WellKnownName>
<sld:Fill>
<sld:CssParameter name="fill">#734a08</sld:CssParameter>
</sld:Fill>
</sld:Mark>
<sld:Size>14</sld:Size>
</sld:Graphic>
</sld:PointSymbolizer>
</sld:Rule>
New in
GeoServer
2.12!

16. Marks composition and override
FOSS4G 2017, Boston
August 14th-19th 2017
[type = 'fountain'][@sd < 6k] {
mark: symbol(circle), symbol(circle);
:nth-mark(1) { fill: #b5d0d0 };
:nth-mark(2) { fill: #576ddf };
mark-size: 10, 3;
[@sd < 3k] {
mark: symbol('file://symbols/fountain.svg');
:mark { fill: #576ddf; };
}
}

17.  Many other options!
 Built-in symbol names (well known marks): circle,
square, triangle, …
 From TTF fonts using the name
ttf://<fontname>#charcode
 Windbarbs, e.g.:
windbarbs://default(15)[kts]
 WKT specification, e.g.
wkt://MULTILINESTRING((-0.25 -0.25, -0.125 -0.25), (0.125 -
0.25, 0.25 -0.25), (-0.25 0.25, -0.125 0.25), (0.125 0.25, 0.25
0.25))
 See more here:
http://docs.geoserver.org/latest/en/user/styling/sld/exte
nsions/pointsymbols.html
Other mark options
FOSS4G 2017, Boston
August 14th-19th 2017

18. Filling polygons
FOSS4G 2017, Boston
August 14th-19th 2017

19. Solid filling
FOSS4G 2017, Boston
August 14th-19th 2017
* {
fill: lightgrey;
stroke: black;
stroke-width: 0.5;
}
<sld:PolygonSymbolizer>
<sld:Fill>
<sld:CssParameter name="fill">#d3d3d3</sld:CssParameter>
</sld:Fill>
<sld:Stroke>
<sld:CssParameter name="stroke-width">0.5</sld:CssParameter>
</sld:Stroke>
</sld:PolygonSymbolizer>

20. Filling with repeating images
fill
FOSS4G 2017, Boston
August 14th-19th 2017
[@sd < 800k][type in ('cemetery', 'grave_yard')] {
fill: #aacbaf;
[@sd < 50k] {
[religion = 'jewish'] {
fill: #aacbaf, url('symbols/grave_yard_jewish.png');
};
[religion = 'christian'] {
fill: #aacbaf, url('symbols/grave_yard_christian.png');
};
[religion = 'INT-generic'] {
fill: #aacbaf, url('symbols/grave_yard_generic.png');
};
};
}

21. Filling with repeating images (SLD)
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:Rule>
<ogc:Filter>
<ogc:And>
<ogc:Or>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>type</ogc:PropertyName>
<ogc:Literal>cemetery</ogc:Literal>
</ogc:PropertyIsEqualTo>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>type</ogc:PropertyName>
<ogc:Literal>grave_yard</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Or>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>religion</ogc:PropertyName>
<ogc:Literal>jewish</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:And>
</ogc:Filter>
<sld:MaxScaleDenominator>50000.0</sld:MaxScaleDenominator>
One sample rule (the Jewish religion one).
Three more needed to get the same
display as with CSS

22. Filling with repeating images (SLD)
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:PolygonSymbolizer>
<sld:Fill>
<sld:CssParameter name="fill">#aacbaf</sld:CssParameter>
</sld:Fill>
</sld:PolygonSymbolizer>
<sld:PolygonSymbolizer>
<sld:Fill>
<sld:GraphicFill>
<sld:Graphic>
<sld:ExternalGraphic>
<sld:OnlineResource
xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:type="simple"
xlink:href="symbols/grave_yard_jewish.png" />
<sld:Format>image/png</sld:Format>
</sld:ExternalGraphic>
</sld:Graphic>
</sld:GraphicFill>
</sld:Fill>
</sld:PolygonSymbolizer>
</sld:Rule>

23. Filling with marks
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:PolygonSymbolizer>
<sld:Fill>
<sld:GraphicFill>
<sld:Graphic>
<sld:Mark>
<sld:WellKnownName>shape://times</sld:WellKnownName>
<sld:Stroke>
<sld:CssParameter name="stroke">#ADD8E6</sld:CssParameter>
</sld:Stroke>
</sld:Mark>
<sld:Size>8</sld:Size>
</sld:Graphic>
</sld:GraphicFill>
</sld:Fill>
</sld:PolygonSymbolizer>
</sld:Rule>
[@scale < 10000] {
fill: symbol('shape://times');
fill-size: 8;
:fill {
stroke: #ADD8E6;
}
}

24. Painting lines
FOSS4G 2017, Boston
August 14th-19th 2017

25. Solid lines (OSM admin borders)
FOSS4G 2017, Boston
August 14th-19th 2017
[type = 'administrative'] {
[admin_level <= 4],
[admin_level = 5 or admin_level = 6][@sd <= 400k],
[admin_level = 7 or admin_level = 8][@sd <= 200k],
[admin_level = 9 or admin_level = 10][@sd <= 100k] {
stroke: #ac46ac;
stroke-opacity: 0.4;
}
}
<!-- 5 different rules with different filters followed by this -->
<sld:LineSymbolizer>
<sld:Stroke>
<sld:CssParameter name="stroke">#ac46ac</sld:CssParameter>
<sld:CssParameter name="stroke-opacity">0.4</sld:CssParameter>
</sld:Stroke>
</sld:LineSymbolizer>

26. Dashes
FOSS4G 2017, Boston
August 14th-19th 2017
…
<sld:LineSymbolizer>
<sld:Stroke>
<sld:CssParameter name="stroke">#6B4900</sld:CssParameter>
<sld:CssParameter name="stroke-width">0.1</sld:CssParameter>
<sld:CssParameter name="stroke-dasharray">2 2</sld:CssParameter>
</sld:Stroke>
</sld:LineSymbolizer>
[@sd < 75k] {
stroke: #6B4900;
stroke-width: 0.1;
stroke-dasharray: 2;
}

27. Alternating dashes with marks
FOSS4G 2017, Boston
August 14th-19th 2017
* {
stroke: darkRed, symbol('circle');
stroke-dasharray: 10 14, 6 18;
stroke-dashoffset: 14, 0;
:stroke {
fill: darkRed;
size: 6;
}
}
 Two coordinated dashed lines
 One made with lines
 One made with circles
 The offset shifts them to have
one appear in the empty
spaces of the other

28. Labeling
FOSS4G 2017, Boston
August 14th-19th 2017

29. Vendor options
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August 14th-19th 2017

30. Point labels and obstacles
FOSS4G 2017, Boston
August 14th-19th 2017
[@sd < 200k] {
label: [FULLNAME];
label-anchor: 0.5 1.0;
label-offset: 0.0 -14.0;
font-fill: #000033;
font-family: Arial;
font-size: 12;
halo-color: white;
halo-radius: 1.5;
label-priority: 200000;
label-auto-wrap: 100;
mark: url('./img/landmarks/${IMAGE}’);
mark-label-obstacle: true;
}
«FULLNAME»
attribute
Auto wrapping
label with halo.
Data driven
symbol URLLabels won’t overlap
the symbol

31. Line labels
FOSS4G 2017, Boston
August 14th-19th 2017
[@sd < 200k] {
label: [LABEL_NAME];
font-fill: #000000;
font-family: Arial;
font-size: 13;
font-style: normal;
font-weight: bold;
halo-color: #FFFFFF;
halo-radius: 1;
label-follow-line: true;
label-repeat: 400;
label-group: true;
label-max-displacement: 200;
}
Draw «LABEL_NAME»,
black, with white halo
Draw them along lines,
fuse segments with
same label, repeat

32. Polygon labels
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:TextSymbolizer>
<sld:Label>
<ogc:PropertyName>FULLNAME</ogc:PropertyName>
</sld:Label>
<sld:Font>
<sld:CssParameter name="font-family">Arial</sld:CssParameter>
<sld:CssParameter name="font-size">14.0</sld:CssParameter>
<sld:CssParameter name="font-weight">bold</sld:CssParameter>
</sld:Font>
<sld:LabelPlacement>
<sld:PointPlacement>
<sld:AnchorPoint>
<sld:AnchorPointX>0.5</sld:AnchorPointX>
<sld:AnchorPointY>0.5</sld:AnchorPointY>
</sld:AnchorPoint>
</sld:PointPlacement>
</sld:LabelPlacement>
<sld:Fill>
<sld:CssParameter name="fill">#000000</sld:CssParameter>
</sld:Fill>
<sld:Priority>50000</sld:Priority>
<sld:VendorOption name="autoWrap">100</sld:VendorOption>
<sld:VendorOption name="maxDisplacement">200</sld:VendorOption>
<sld:VendorOption name="goodnessOfFit">0.9</sld:VendorOption>
</sld:TextSymbolizer>

33. Support for pre-laid-out labels
FOSS4G 2017, Boston
August 14th-19th 2017

34. Raster styling
FOSS4G 2017, Boston
August 14th-19th 2017

35. A DEM and a color map
FOSS4G 2016, Bonn
24nd – 24th August 2016
 SRTM from USGS
 Standard color map
 No-data natively
transparent in 2.8.x
thanks to JAI-EXT
[@sd > 75000] {
raster-channels: auto;
raster-color-map:
color-map-entry(#00BFBF, -100.0, 0)
color-map-entry(#00FF00, 920.0, 0)
color-map-entry(#00FF00, 920.0, 1.0)
color-map-entry(#FFFF00, 1940.0, 1.0)
color-map-entry(#FFFF00, 1940.0, 1.0)
color-map-entry(#FF7F00, 2960.0, 1.0)
color-map-entry(#FF7F00, 2960.0, 1.0)
color-map-entry(#BF7F3F, 3980.0, 1.0)
color-map-entry(#BF7F3F, 3980.0, 1.0)
color-map-entry(#141514, 5000.0, 1.0);
}

36. Contrast enhancement
http://docs.geoserver.org/latest/en/user/styling/sld-
reference/rastersymbolizer.html#contrastenhancement
FOSS4G 2017, Boston
August 14th-19th 2017
<sld:RasterSymbolizer>
<sld:ContrastEnhancement>
<sld:Normalize>
<sld:VendorOption name="algorithm">
StretchToMinimumMaximum
</sld:VendorOption>
<sld:VendorOption name="minValue">50</sld:VendorOption>
<sld:VendorOption name="maxValue">800</sld:VendorOption>
</sld:Normalize>
</sld:ContrastEnhancement>
</sld:RasterSymbolizer>
GeoServer
vendor extension

37. Other assorted features
FOSS4G 2017, Boston
August 14th-19th 2017

38. Geometry transformations
FOSS4G 2017, Boston
August 14th-19th 2017
[@scale < 10000] {
fill-geometry: [offset(the_geom, 6, -6)];
fill: darkgray;
z-index: 0;
}
[@scale < 10000] {
fill: #b3b3b3;
z-index: 1;
}

39. Rendering transformations
FOSS4G 2017, Boston
August 14th-19th 2017
* {
transform: ras:Contour(levels:
1100 1200 1300 1400
1500 1600 1700 1800);
stroke: black;
label: [GRAY-INDEX];
font-fill: black;
font-family: Sans;
font-size: 12;
halo-radius: 2;
halo-color: white;
label-follow-line: true
}

40. Masking via alpha compositing
FOSS4G 2016, Bonn
24nd – 24th August 2016
destination-in

41. Color blendin
FOSS4G 2017, Boston
August 14th-19th 2017
http://docs.geoserver.org/stable/user/styling/sld-extensions/composite-blend/index.html
More info at:

42. Z ordering
http://docs.geoserver.org/latest/en/user/styling/sld-
extensions/z-order/example.html
FOSS4G 2017, Boston
August 14th-19th 2017
[class = 'motorways'] {
stroke: #990000;
stroke-width: 8;
z-index: 0;
}
[class = 'railways'] {
stroke: #333333;
stroke-width: 3;
z-index: 2;
}
[class = 'railways'] {
stroke: #ffffff;
stroke-width: 1.5;
stroke-dasharray: 5, 5;
z-index: 3;
}
[class = 'motorways'] {
stroke: #ff6666;
stroke-width: 6;
stroke-linecap: round;
z-index: 3;
}
* {
sort-by: "z_order";
sort-by-group: "roadsGroup";
}

43. New in 2.12
FOSS4G 2017, Boston
August 14th-19th 2017

44. Autocomplete for CSS editor
 Because there are too many properties to
remember!
FOSS4G 2017, Boston
August 14th-19th 2017

45. No more -gt- prefix in CSS
 Vendor options used to be prefixed with “-gt-”
 But CSS is its own language, no need to mark
something as “vendor” or refer to GeoTools
 Don’t worry, old syntax still supported
FOSS4G 2017, Boston
August 14th-19th 2017
* {
...
-gt-mark-label-obstacle: true;
-gt-label-priority: 200000;
-gt-label-auto-wrap: 100;
}
* {
...
mark-label-obstacle: true;
label-priority: 200000;
label-auto-wrap: 100;
}

46. GeoCSS env variable expansion
 Use @var or @var(defaultValue) in place of calling the
env function
 @var -> env(‘var’)
 @var(defaultValue)  env(‘var’, defaultValue)
 Exception for @sd
 @sd -> env(‘wms_scale_denominator’)
 to get a more fluent syntax for scale dependencies
 New in 2.12
FOSS4G 2017, Boston
August 14th-19th 2017

47. Underline and strikethrough
 New vendor options to control underline and
strikethrough
FOSS4G 2017, Boston
August 14th-19th 2017
<VendorOption name="underlineText">true</VendorOption>
<VendorOption name="strikethroughText">true</VendorOption>

48. Char and word spacing
 Control how much space there is between each
char
 And between words
FOSS4G 2017, Boston
August 14th-19th 2017
<VendorOption name="charSpacing">3</VendorOption>
<VendorOption name="wordSpacing">5</VendorOption>
charSpacing = 3 wordSpacing = 5

49. SVG marks
 Refer to a SVG file insinde
mark/WellKnownMark
 The outline of the SVG will be extracted
 Then filled and stroked as requested
 Suitable for simple shapes
FOSS4G 2017, Boston
August 14th-19th 2017
:mark {
fill: red;
stroke: yellow;
stroke-width: 3;
stroke-opacity: 50%;
}

50. More QGIS SLD export work
 In QGIS 3.0 support for label exports (thanks for
OpenGeoGroep sponsoring)
 Want to see more? Help us fund the effort 
FOSS4G 2017, Boston
August 14th-19th 2017

51. That’s all folks!
Questions?
info@geo-solutions.it
FOSS4G 2017, Boston
August 14th-19th 2017