I found this an interesting challenge, so I gave it a shot after
@Hornet1ba generously permitted me to do so.
Converting a Daz3D render to a photorealistic image is easy enough. But doing so while preserving the likeness of a face is a different matter, for which I could see no clear solution.
My first attempt was to use as many controlnet images as possible to capture the essential traits from the original. Normally, I'd use just the lineart model as stacking up controlnet images tend to deteriorate the image quality. And because lineart is generally not enough to preserve the likeness of a face, I also tried to use canny and reference models which I don't use very often.
Also, I experimented with normal and colour, hoping they might help transfer finer details and colours of the face respectively. It didn't work well which made me doubt the usefulness of those particular control net models.
As expected, using that many controlnet images together made it look rather unrealistic. So I masked the face area to preserve its content then inpainted the other area using just lineart and depth, which resulted as below:
View attachment 1322101
Note that I didn't bother to depict the nails and the blood because it's not the main challenge in this case. I already showed that it's doable in another render of mine before.
I wasn't happy with the result entirely (especially the skin tone, and the way the cross looks) so I decided to try it again using a different approach.
This time I started as usual, trying to find the right tone and lighting first using only the essential controlnet images. The result looked more realistic than before but the character didn't resemble the original as much, which was quite expected.
So, I just inpainted the face area using a similar controlnet setup as used in the first experiment. It restored the resemblance somewhat but had the side effect of reintroducing the "3D render like" feel to the face. So I ran it through a series of img2img processes using reduced reference model influence. It mitigated the issue but didn't eliminate it entirely.
It seems that it's a matter of choosing the right spot between the perfect likeness and the Daz3D-looking uncanny valley. So, below is the point I chose between those two extremes:
View attachment 1322104
Again, converting a 3D render to a photorealistic image itself isn't a difficult task, and it's quite easy to render images in the likeness of a given character if there's a sufficient number of reference photos.
But converting a single 3D render into a photorealistic image without destroying the likeness of the character can be a more difficult problem. So I took it as a challenge and a chance to learn control models that I haven't used much. And I'm glad that I did since I learned much from this experiment
Again, thanks
@Hornet1ba for allowing me to use his original work!