Medium quality STL:
STL is a mesh format, which means that it contains triangles, and nothing else (in case of Shapr, otherwise you could store color and lighting information in this format). This format is intended to be used for 3D printing at home with your filament based printer. This is why we are giving this for free: we are 3D printing enthusiasts, and we believe that Shapr will be one of the easiest and most affordable tools for hobbyists.
High quality STL:
Format is the same, quality is higher. If you want to use Shapr with CNC machines, or have a more expensive SLA printer, for example a Form2, you should go for Shapr3D PRO, and use the high quality STL export. This export format will create an ultra high quality, super precise STL from your model.
We are quite often asked what do these precision categories actually mean in millimeters. The answer is that precision is defined by maximal deflections.
For medium quality STL angular deflection is 0.45, and deflection is 0.1, for high quality STL angular deflection is 0.05 and deflection is 0.0025. In case if someone would need it, we could offer even higher quality STLs, but we think the current high quality STL is balanced very well between performance/file size/precision. Or we could even offer a user interface, where you could set these values to arbitrary values.
PRO file formats:
STEP is the ultimate data format for CAD data exchange. It is an awesome standard, that is meant to become the number 1 data exchange format between different CAD systems - and it actually does a great job at this. If you want to use Shapr with any other CAD, you should go with STEP export, since this file format is compatible with ALL the major 3D modeling systems (SolidWorks, CATIA, Rhino, Onshape, PRO/E, Creo, AutoCAD, you name it. Everything.) Based on user feedback, Shapr's STEP export is very robust, and does a really great job, just look at this Mars ROVR (pun intended) that I made in and exported from Shapr and imported to Rhino.
There are many really complex features in this model, complex fillets, lofts, nurbs surfaces, revolved bodies, extrusions, etc. and Rhino imported it like a charm. Wow.
The awesome GrabCAD guys wrote a great article about IGES, so I will just quote the most important sentence from that article:
But a word of caution: while STEP and IGES are often grouped together in the same breath, they are certainly not equivalent. In fact, if formats were horses, it's probably time to send the IGES pony to the glue factory.
Why do we support IGES then?
1. Because we can
2. In some very rare cases it can be useful. But you should always go with STEP if you can.
Shapr can handle STEP and IGES imports, and you can use the imported models just like if you created them in the app. It can handle really complex models, and with an upcoming update (2 weeks), you will get our brand new, and super polished rendering engine, so even for really complex imported models you won't notice any lag. Yes, the iPad Pro is really that powerful.
Why don't you guys support STL imports? I really want that!
Shapr3D is a so called solid modeler. This means that the underlying representation in Shapr are parametric surfaces and parametric curves. However, STL contains just a set of triangles. Thus importing STL would mean that we would have to convert a set of (maybe poorly connected) triangles to well connected surfaces. Do you know how to do that? No? Neither do we! Okay, just kidding, actually we do have some ideas how to do that, but that would be really, really hard to do, BUT we do have plans for doing this, maybe next year. But actually STL was never meant to be an input format for CAD, so if you want to import models, you may want to take a look at GrabCAD, where you can find lots of high quality models in STEP and IGES formats.