I have a map comprised of three different sources of mosaiced DEM (two Lidar and one 1/3 arcsec float nationalmap DEM) which show up entirely intact in ArcMap (10.2.2), when I export to PDF at a DPI over 300 or even as a lossless TIF file, parts of the DEM drop out and are white. The vector graphics (line or area) are intact over the white space, just the DEM is not there. It does not affect one source of data exclusively, and the missing sections are not consistent from export to export. Also, in my elevation legend, one of the ticks for the elevation numbers comes through looking fatter than the other ticks... All of these are circled on the attached screen shot: ArcMap on left, PDF and zoomed in screenshot of PDF on right. Does anyone have any idea how to combat this? 200 dpi is not acceptable!