Example of a cylindrical lithophane made with PhotoToMesh
Here is the starting photo:
And here is the final cylindrical lithophane, lit internally:
And here is the the same lithophane, lit externally:
I've deliberately used external lighting from the side in order to show better the 3D bas relief effect.
So, how to get from the photo to the cylindrical lithophane?
First get hold of your photo (from a scanner or digital camera) and bring it into PhotoToMesh. You will be given the opportunity to change the image's contrast and brightness, rotate it, as well as crop it:
The original photo does not need to be black and white, though in this case it was.
Once in PhotoToMesh you need to choose Cylindrical Mesh as the solid shape, and set a few other things:
Most of the settings above are self explanatory, For lithophanes you need to click on Invert Mesh so that dark areas have more material when you come to create the real object. You can see check box for that in the middle of the dialog above.
Also it seems that a wall thickness of 0.5mm and a mesh height (the maximum extra material added to darken the image) should be set at about 2.0mm. Your settings may be a bit different, it depends on the sort of plastic you use and and the strength of the light you will put inside the cylinder.
You'll notice that the greyscale image has some white shading at the left and right edges. This fading was not in the original photo, I've added it using the Vignette Settings. You can also see that the shoulder of the man blends in with the rest of the object in the 3D view. This is because of the vignette settings:
The original photo is on the left, and I've set a vertical band as the vignette, and the "vignetted" photo (actually a heightfield) is on the right. This has the result of "merging" the left and right edges of the "bas relief" into the mesh of the cylinder.
When you are in the main dialog of PhotoToMesh you can see either the original image or the vignetted version by clicking on the radio buttons in the middle left.
If we have a look at the final object again you'll just about be able to see the effect of the fading at the bottom left and bottom right:
Now, just save your work as an STL file and create the real object on your CNC machine or 3D printer. Jamie Wilson did this one for me, his printer is better than mine!
What I find amazing about lithophanes is that they can give that impression of a photograph. Look for example at the detail near the collar and tie in the above photo, and in the actual 3D printed object:
PhotoToMesh costs $44.95, and you can try before you buy, just download the (Windows only) demo: