We asked Hervàs about the specific technique behind these images. He wouldn’t tell us, but instead reiterated the project’s description (and the reason why he makes the images):
How can we accept that we are changing?
How can we accept we hardly recognize ourselves in certain situations?
I am changing at this very moment of my life.
I do not react in the same ways I used to. I am surprised. Is that me?
These pictures are the way I see myself now.
My shadow is there but I erase myself because I don´t know who I am any longer.
The shoes remain only to make sure there is something more than… a shadow.
The technique is likely extremely simple: shoot two photographs — one of just your shoes, and one of yourself standing in that location — and then blend the two images together in Photoshop.
You can find more of his work over on his Flickr page.