Using the Marlin Renderer with Spectrum Spatial
This section is only applicable to Oracle Java 8. There is no need to download the jar for Azul JDK because it is bundled with JDK, and the Marlin Renderer is enabled by default.
Spectrum Spatial renders maps and map tiles with anti-aliasing (Quality) enabled. Spectrum Spatial uses the default Ductus renderer that comes with Java 8, which does not scale its anti-aliasing. Starting with version 12.0 of Spectrum Spatial, images of maps and map tiles are only produced with anti-aliasing. This means if you have images that require a lot of anti-aliasing, it is possible you will see a lack of scaling.
A very simple way to ensure that rendering is scalable with anti-aliasing enabled is to use the Marlin renderer, "an open source (GPL2+CP) Java2D RenderingEngine optimized for performance." The new map images may be slightly different but not by a noticeable amount.
These instructions below specifically describe how to integrate the Marlin renderer with Spectrum Spatial.
Changes take effect immediately.
You should see this in the spectrum-server.log file:
INFO: ===============================================================================
INFO: Marlin software rasterizer = ENABLED
INFO: Version = [marlin-X.Y]
INFO: sun.java2d.renderer = org.marlin.pisces.MarlinRenderingEngine
...
If you do not see this in your spectrum-server.log after you initialize the Mapping Service with a mapping request, then something was misconfigured.