In this section I'd like to go over the three different programs I've used and come to love for generating lithophane STL's. Each one has it's advantages and some with limitations, I'll try and briefly go over what settings I use for each one. I'll post links to each of the three generators on the Download & Links page.
This was the first generator I used and it works great, but is somewhat limiting on size. If you want to print small lampshades or nightlights this is a great way to get into lithophane making as it's quite easy to learn for beginners and quite effective. Below are some of the important settings I've used and is fairly self explanatory.
Change the slider from Negative to Positive! For some unknown reason the creator of this has it set to Negative as default.
Will be the longest dimension of your picture, the other dimension will uniformly scale.
This is very important depending on what filament you are using and how much contrast it has. .8 to 3.0 is very standard for many filaments
"Vectors Per Pixel"
This will increase your quality, but really bog down your search engine and possibly crash if you have too big of a picture. I find this program runs MUCH smoother and crashes less in Mozilla Firefox. I usually tried to keep vectors set at 5 or greater.
This will allow you to add a curve to your lithophane if you like that look or want to make a nightlight out of it.
Everything here is pretty much the same, but it's important to note that you should use Outer Curve under Model and then go into "Settings/Model Settings" and slide "Curve" up to 360 degrees.
Tom Brooks at Lithophanemaker has created a very intuitive tool/website which allows anyone to easily create quality STL's for many different style lithophanes and it's VERY customizable... and FREE! This has become my go to for generating STL's. I'll leave a link on my download/links page to the website.
You select what it is you want to make (Lampshade, Lightbox, Night Light, Framed Flat, Circular or Curved) from the front page and follow directions. Once you have your settings typed in you can click the "Create .stl" button and you'll receive a zipped download with the STL and settings in it.
LithophaneMaker will generate an STL with as much quality as you want or as much as your slicer can handle. Typically Cura won't open an STL over 500MB or it will, but it'll be extremely slow in slicing. I believe S3D will, but bigger STL sizes don't always mean better quality!
I've seen 1GB STL prints from a VERY high resolution picture have "okay" quality. It all has to do with how it's printed/presented (physical size, STL settings, slicer settings, filament used, backlighting, calibration on printer among other things).
PTM allows you to quickly and easily generate just about any type of lithophane you want. The biggest CON I'd have for this would be that it's not free, I believe it cost $35-$50 (for 3 years) depending on what version you get, but is a GREAT program and worth it.
Before I go into settings I'd like to describe how I find the picture I want to use. I try and find the highest resolution image I can, once I do this I try and get the sum of the resolutions as close to 3000 as I can. For example, if you have a picture with a resolution of 1920x1080, the sum of both numbers (1920+1080) is 3000.
For a basic flat lithophane you want to select Rectangular Slab from the "Solid Shape" dropdown menu.
If you play with image placement you can slightly shrink the picture within the lithophane and this will add a frame around the lithophane if desired.
"X and Y Samples"
If you are using Cura3.6 to slice you are limited to the size of the STL you can open. This size is usually around 480-520MB, if you exceed this Cura will tell you that you have an invalid file. I try and generate files as close to 450MB as I can get (give or take). The physical size of the lithophane doesn't affect the STL size. What controls the STL size are the X and Y samples. Once you have a picture with a resolution "sum" close to 3000 as described above you use these two numbers for your X and Y samples. This will generate a file right around 450MB.
If you have a picture with crazy high resolution you can just open it in a photo editor and change your pixels uniformly until you reach something close to 3000.
"Length/Width of solid"
First I like to check "Lock Y Dimension" so only one box will be highlighted and let you enter a number, the other dimension will automatically fill in to keep the size proportional.
"Z-Height of mesh and Slab thickness"
This is pretty straight forward as well. Your slab thickness is going to be your min thickness.... usually this is .8 if your using a .4 nozzle.
The Z Height is the additional height above the slab height, 2.2 is quite common.
Using .8 for slab thickness and 2.2 for Z-Height would generate an STL with a min/max of .8-3mm.
I almost always use 0 for smoothing as it creates the most detail. There may be some images where smoothing would be desired, but I just keep it at 0 for pretty much everything I do.
Once you get all your settings to where you want them, click on "Recreate Model". Depending on how fast your computer is this may take a minute. Once it creates the STL go to File and Save STL to your computer... this could also take a couple minutes, but than that's it your DONE creating the STL.