Mathematica doesn't do the best job of exporting figures with shading or transparency to vector graphics formats such as PDF. 

A common trick employed here and elsewhere on the web to workaround this is to rasterize just the image portion of the figure and insert this back into a vector version of the axes, labels etc. 

The axes are typically converted to a vector drawing by the command: 

    ImportString[ExportString[axes, "EPS"]]

However this appears to no longer work on V11. More specifically I'm not sure `ExportString[axes, "EPS"]]` is behaving as it should, certainly it's output is very different between V10 and V11.

Complete test case:

    fig = Plot3D[Sin[x + y^2], {x, -3, 3}, {y, -2, 2}]
    axes = Graphics3D[{}, AbsoluteOptions[fig]]
    ExportString[axes, "EPS"]

Outputs at pastebin:

[V10][1], [V11][2]


The V10 output is all understandable and can be correctly imported via `ImportString` in both V10 and V11. However the V11 output contains what looks to be compressed data in the form 

> ...g&[ie9oJbc5;SLF=49tG:f #EsI8)63Mg(KS!"/5i2neP :F"d@<>E99o<D$TG[(Zimrd=eIZ2E)DH...

and cannot be imported by either V10 or V11.


So, am I missing something or is `ExportString[...,"EPS"]` not working correctly in V11?

If so, what is a suitable workaround?

**EDITS**

Note also that simply exporting to an EPS figure via `Export` also does not produce a vector image.

The option `"AllowRasterization -> False"` does not help for either `Export` or `ExportString` however setting it to `True` results in an even more coarsely rasterized image!


Screenshot of a section of the V11 output to show formatting:

[![enter image description here][3]][3]


  [1]: http://pastebin.com/xRzkW8V0
  [2]: http://pastebin.com/A6gWQJYw
  [3]: https://i.sstatic.net/iDaIw.png