How to determine what is visible

I'm working on finding all the horizontal and vertical lines/paths/rectangles of a PDF file by analyzing the operands adn operators.  Most of the PDF files are drafted with Adobe InDesign.  I'm running into some problems where it appears that only certain things are visible in the PDF but there are many lines and other things not visible when Acrobat draws the PDF.  Is there a way to tell which objects will be visible when the PDF is rendered to the screen with Acrobat?

Attached is pdf.jpg which is a cropped image of what Acrobat draws to the screen.  Also attached is wireframe.jpg which is what PitStop Pro shows when wireframe viewing is enabled of the same region of the PDF as pdf.jpg.  You can see that there are dozens of lines, paths, rectangles, etc that are not visible when Acrobat draws it to the screen.  With my line finding routine, i only want to find the lines that are visible.  (The original PDF is also attached)

I've already filtered out (rightly or wrongly) things that are not stroked, not filled, and clipping paths but there are still "tons" of "invisible" objects.

Thanks for your consideration.
Darren