When you create print composer output pdf, the vector layers are converted
in pdf by using all points present in the layer entities. If you use of bulky
layers, this results in large size pdf. In QGis version 2.12 you have a new
option that allows you to settle this problem .
Let’s consider as example the Geofla Commons layer. To appreciate the difference we will
not charge anything else . We open the print composer:
And we export as pdf the content of the composer . The resulting pdf
file (VectorMap.pdf) is 20 MB.
Now we are going to repeat the operation, but firstly we will change the
rendering of the Commons layer.
We open the window Properties->Rendering of the layer :
And we tick the option Force the display of
the layer as a raster .
At the composer layer, the Commons map is loaded. At first sight we do
not perceive any difference .
If, now, we export as pdf the content of the print composer as MapRaster.pdf
You can find that the output file size has been divided by 10.
You can compare the rendering of the pdf;
Rendering as pdf with a 600% zoom of the rasterized layer
Rendering as pdf with a 600% zoom of the vector layer . [ / caption]
Rendering in pdf with a 600% zoom of the layer vector .