I posted a little while back about issues with the quality of PDFs I have been exporting from ArcMap 9.2.
I have some very large (A0) detailed maps with several groups of layers and multiple dataframes involved and I am PDFing them via export.
I noticed that on some of my dataframes the base mapping was very crisp - vector like sharp. However on others is was rasterising and was poor quality.
I have now worked out with the aid of a colleague that this is down to some of my layers having transparency and it seems anything below these layers just becomes raster based when exporting to PDF.
My question therefore is, is there a way to stop this? Removing transparency/reordering the layers is not an option at this point.