Hi Jay, the hidden line determination works by keeping track of depth values on a pixel grid - if there aren't enough pixels then you'll get a side effect like you show there. So you can't use a low resolution image size if you want to get rid of those, you will need to use a higher resolution image to solve that.

The image size is controlled by the "Canvas megapixel resolution" option, which controls both the depth resolving pixel grid and the size of the shaded background image as well. I've thought some about having separate values for those because right now if you increase the density to get better hidden line removal it also increases file size of the PDF since it will have a big image in it.

- Michael