Mapping in GeoServer with SLD and CSS
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Advanced cartographic map rendering in GeoServer Ing. Andrea Aime, GeoSolutions FOSS4G 2014, Portland 8 th -13 th September 2014
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Various software can style maps and generate a proper SLD document for OGC compliant WMS like GeoServer to use. However, in most occasions, the styling allowed by the graphical tools is pretty limited and not good enough to achieve good looking, readable and efficient cartographic output. For those that like to write their own styles CSS also represents a nice alternatives thanks to its compact-ness and expressiveness. Several topics will be covered, providing examples in both SLD and CSS for each, including: mastering multi-scale styling, using GeoServer extensions to build common hatch patterns, line styling beyond the basics, such as cased lines, controlling symbols along a line and the way they repeat, leveraging TTF symbol fonts and SVGs to generate good looking point thematic maps, using the full power of GeoServer label lay-outing tools to build pleasant, informative maps on both point, polygon and line layers, including adding road plates around labels, leverage the labelling subsystem conflict resolution engine to avoid overlaps in stand alone point symbology, blending charts into a map, dynamically transform data during rendering to get more explicative maps without the need to pre-process a large amount of views. The presentation aims to provide the attendees with enough information to master SLD/CSS documents and most of GeoServer extensions to generate fast, appealing, informative and readable maps.
Transcript of Mapping in GeoServer with SLD and CSS
Advanced cartographic map rendering in GeoServer
Ing. Andrea Aime, GeoSolutions
FOSS4G 2014, Portland 8th-13th September 2014
Overview
Who we are
Example map
Raster styling
Scale dependent rules
Hatches, patterns and dashes
Point Symbology
Labeling
Transformations
Cross layer filtering
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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
GeoTools, GeoServer
GeoBatch, GeoNetwork
Clients
Public Agencies
Private Companies
http://www.geo-solutions.it
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Introduction
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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)
Showing the full style, it’s that short
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Example map
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Example map
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Example map
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Example map
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Example map
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Raster styling
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A DEM and a color map
SRTM from USGS
Standard color map
Just avoid the nodata values with opacity=0
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A DEM and a color map
Same as before, in CSS
Solid intervals
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Hatches, patterns, dashes and plates
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Filling with patterns
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Filling with TTF fonts
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Hatches
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Hatches
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shape://vertiline shape://horline
shape://slash shape://backslash
shape://plus shape://times
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Dashes
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Dashes
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Plates
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Plates CSS way
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Point Symbology
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Point symbols
• 600 loc for 6 different points types
• Painful…
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Point symbols
• 70 lines total • Power of cascading
…
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Dynamic symbolizers
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Dynamic symbolizers CSS way
• Down to 15 lines
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Labeling
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Line labels
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Line labels (and more) CSS way
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Point labels
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Polygon labels
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Label Obstacles
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Scale dependent rules
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Scale dependent rules
Too often forgotten or little used, yet very important:
Hide layers when too zoomed in (raster/vector example)
Progressively show details
Add more expensive rendering when there are less features
Key to any high performance / good looking map
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Example
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Hide as you zoom in
Add a MinScaleDenominator to the rule
This will make the layer disappear at 1:75000 (towards 1:1)
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Alternative rendering
Simple rendering at low scale (up to 1:2000)
More complex rendering when zoomed in (1:1999 and above)
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Alternative rendering
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Alternative rendering, CSS way
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Transformations
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Geometry transformations
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Geometry transformations CSS way
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Rendering tx: isolines
• No CSS support yet
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Rendering tx: point extraction
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Rendering tx: dynamic color map
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QGIS palettes
GDAL pam stats
Input raster
Dynamic ColorMap
Map!
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Wind barbs
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windbarbs://$(value)[m/s]?emisphere=(n/s)
windbarbs://15 [m/s]?emisphere=n
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