In a response to the article, the author clarifies, "Art: in re-reading my article, I see that I wasn’t very clear… I used software (in my case Paintshop Pro X2) to create multiple layers and use masking. Any software like Photoshop that allows that functionality would be usable to do VGND."
Sounds like it's pretty labor intensive, but the results are nice.
In the world of imaginary products, I'm trying to find a SVGND - Smart Virtual Neutral Density Filter, i.e., one that automatically recognizes the contrast line.
What eNo is describing is the original HDR, that is, until the software came along. One method, HDR was done by hand with a couple exposures. One shot for the highlights and one for shadows. There are other ways too
I've photographed jagged scenes like the bottom example in the article with a soft transition grad ND and the results look perfectly normal. So you don't necessarily need a completely flat scene to get acceptable results with a soft transition GND. I've never tried a hard stop one, but yeah that might be a little more touchy.
No, no, goodness, no. I am not peddling software with this write-up.
This is merely a layer/masking technique -- nothing new really -- but which can also be used to make a composite of two exposures. As FisherPete indicates, I left clarification in one of the responses... Maybe I should edit the article to make things clearer.