'High resolution image with Mapnik
I use Mapnik 2.2.0 to render a map from my Java library using the Mapnik JNI. This is working fine with no issues. I am now trying to make the map available in high resolution.
I changed the image size in my code from 256x256 to 512x512. This caused Mapnik to change the effective zoom level, because the scale has changed. For example, when rendering 15/5000/10000, I see a 512x512 image with my zoom 16 styling.
What I want to have is an image of the same coordinates as my original 256x256 image, with the same styling, only 512x512.
I found a possible parameter that could be related:
<Parameter name="scale">2</Parameter>
where 2 should be the factor I need. However it did not have any effect on the rendered image, so I may be looking the wrong direction.
Solution 1:[1]
Turns out that the Mapnik JNI renderAgg signature that I was using:
renderAgg(MapDefinition map, Image image)
sets the scale factor to 1.0. When I changed to this signature:
renderAgg(MapDefinition map, Image image, double scaleFactor, int offsetX, int offsetY)
The scale factor took effect
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | bbk007 |