Kore Nordmann has been making great strides on his Image_3D PEAR package and now, with some help from his brother, the package can display the images created as SVG images in a browser. Additionally, this post mentions the inclusion of "subdivision surfaces" to smooth images rendered.
This one enables you to display the threedimensional scenes created by Image_3D in your browser as a SVG. Plus you get several buttons to modify the SVG directly in your browser. For now you can move and zoom the scene - but there will be some more transformations in the near future.
The "subdivision surfaces" (adding more polygons to a surface) helps to create a smoother look to the image and has been implemented by Kore. Using it is a simple matter of calling the subdivideSurfaces() function on your object with the detail level you want.
You can check out samples of both of these enhancements on Kore's blog.