Blender is a whole separate program. It's similar to Inkscape in being an open source project, and having vector support. But other than that, they are not related. A lot of people use Inkscape and Blender together though. Typically they start creating the basic parts of the drawing in Inkscape, and then import to Blender to make it 3d. I'm sure you'll find plenty of tutorials and/or manual for Blender.
I have attached another example. Flat surface the image stands proud of the surface. Isn't that called a carving?
I understand completely what you're talking about. Inkscape cannot make the kind of drawing (3d rendering) you showed (but Blender can).
Seems the big issue is getting the photo in the right format. Once the photo is prepared, all that is needed is to carve it....right???
Well, if you need a 2D rendering of a 3D object, to use as a model, to carve it by hand, I would say "right". The question I can't answer, is whether you actually need a 3d rendering to accomplish the CNC carving. Maybe you do, I just don't know.
To my understanding, what you need is the proper code to send to your CNC. If your machine is such that you can import the 3d rendering, and it magically carves it out, then I would say that's some really awesome soft and hardware! That would mean that the machine is creating some kind of code from the image, and the code drives the cutting tools.
But what I've learned from my brief experience with Inkscape's gcode tools, is that you need to give the CNC the proper code. I think it's possible Inkscape can produce the proper code, but as I explained before, I'm not positive.
I'm really sorry that we can't get any help from the developers of Inkscape's gcode tools. In another recent topic, I learned about another program which produces gcode, and I assume other kinds of code for CNC. It has a free trial version, afaict. It's called ESTLCAM. I have no idea if it can do what you want. And unfortunately, half their website is in German, and I don't have time to get it translated right now.
I'm going to post a message to Inkscape's development mailing list, informing of the lack of support from the gcode tools makers, and asking if there are others in the community who can help. I'll post here when I get an answer. (answer could come right away, or could take a couple of days, but I'll post what I learn.)