Creating Stunning Maps in GeoServer: mastering SLD and CSS styles

Creating stunning maps

with GeoServerMastering SLD and CSS

Ing. Andrea AimeGeoSolutions

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, BostonAugust 14th-19th 2017

http://www.geo-solutions.it/

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)


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


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


[admin_level < 2][@sd < 1M][@sd > 100k] {label: name;font-family: ‘Noto Sans’;…/* this is nested rule */[special = true][@sd < 500k] {font-weight: bold;…

}}

SLD equivalents


<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

Scale dependencies


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


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


Unit of Measure


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;

}

Transformation functions


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

Transformation functions in SLD


<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>

Point styling


Simple symbol


[type = 'alpine_hut'][@sd < 100k] {mark: url('symbols/alpinehut.p.16.png');

}


<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>

Marks (SVG in this case)


[type = 'bank'][@sd < 6k] {mark: symbol('file://symbols/bank.svg');:mark { fill: #734a08 };mark-size: 14;

}


<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!

Marks composition and override


[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; };

}}

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/extensions/pointsymbols.html

Other mark options


http://docs.geoserver.org/latest/en/user/styling/sld/extensions/pointsymbols.html

Filling polygons


Solid filling


* { 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>

Filling with repeating images

fill


[@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');};

};}

Filling with repeating images (SLD)


<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

Filling with repeating images (SLD)


<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:OnlineResourcexmlns: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>

Filling with marks


<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; }

}

Painting lines


Solid lines (OSM admin borders)


[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;

}}

<sld:LineSymbolizer><sld:Stroke><sld:CssParameter name="stroke">#ac46ac</sld:CssParameter><sld:CssParameter name="stroke-opacity">0.4</sld:CssParameter>


Dashes


…<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>


[@sd < 75k] {stroke: #6B4900;stroke-width: 0.1;stroke-dasharray: 2;

}

Alternating dashes with marks


* { 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

Labeling


Vendor options


Point labels and obstacles


[@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

Line labels


[@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

Polygon labels


<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>

Support for pre-laid-out labels


Raster styling


A DEM and a color map

FOSS4G 2016, Bonn24nd – 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);

}

Contrast enhancement

http://docs.geoserver.org/latest/en/user/styling/sld-

reference/rastersymbolizer.html#contrastenhancement


<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

http://docs.geoserver.org/latest/en/user/styling/sld-reference/rastersymbolizer.html#contrastenhancement

Other assorted features


Geometry transformations


[@scale < 10000] {fill-geometry: [offset(the_geom, 6, -6)];fill: darkgray;z-index: 0;

}

[@scale < 10000] {fill: #b3b3b3;z-index: 1;

}

Rendering transformations


* {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

}

Masking via alpha compositing

FOSS4G 2016, Bonn24nd – 24th August 2016

destination-in

Color blendin


http://docs.geoserver.org/stable/user/styling/sld-extensions/composite-blend/index.html

More info at:

http://docs.geoserver.org/stable/user/styling/sld-extensions/composite-blend/index.html

Z ordering

http://docs.geoserver.org/latest/en/user/styling/sld-

extensions/z-order/example.html


[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";}

http://docs.geoserver.org/latest/en/user/styling/sld-extensions/z-order/example.html

New in 2.12


Autocomplete for CSS editor

Because there are too many properties to remember!


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


* {...-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;

}

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


Underline and strikethrough

New vendor options to control underline and strikethrough


<VendorOption name="underlineText">true</VendorOption><VendorOption name="strikethroughText">true</VendorOption>

Char and word spacing

Control how much space there is between each char

And between words


<VendorOption name="charSpacing">3</VendorOption><VendorOption name="wordSpacing">5</VendorOption>

charSpacing = 3 wordSpacing = 5

SVG marks

Refer to a SVG file insindemark/WellKnownMark

The outline of the SVG will be extracted

Then filled and stroked as requested

Suitable for simple shapes


:mark {fill: red;stroke: yellow;stroke-width: 3;stroke-opacity: 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


That’s all folks!

[email protected]

Technology

Creating Stunning Maps in GeoServer: mastering SLD and CSS styles