I think there should be some further discussion about formats. STL is certainly something of an industry standard - but it's a really terrible file format. Close to being the worst I could imagine!
It should be easily possible to convert better formats INTO STL but converting things out of STL will result in massive information loss.
For example: colour and texture cannot be represented in STL. For a simple 3D printer, that's not important - but how long will it be before we might have machines that can mix plastic in three primary colours to generate coloured models? If we encourage people to discard colour and texture information then this transition to colour RepRap will be essentially trapped by the fact of there being no coloured models for them to replicate.
Better to at least ARCHIVE models in a more comprehensive format and convert them to STL (or some other RepRap format) by discarding the colour information.
Also, from my experience in the closely parallel field of 3D graphics, it is commonly the case that the person who generates the information is best equipped with the tools to interconvert file formats - someone who makes 3D models has (of course) some kind of a 3D modeller - and all of those have format conversion features out the wazoo. But our imaginary 3rd world consumer of that data has a minimal set of OpenSourced tools - and is very likely to be unable to read files in more than a couple of formats (nor yet to have the skills to do the conversion correctly).
I think it is worthwhile looking for a standard format that is widely exportable *AND* completely, 100% Open in order that the big evil corporations won't be able to lock up content with DRM and other shit.
If I had to make a snap decision, I'd say 'Collada' was such a format. It's a widely agreed format - it's designed with portability between tools - it's extensible (so we could, for example, add hints such as the best orientation for the model while it's being replicated). It's also XML-based which means it's Open - and it's well documented and supported.
You can write Collada files from most 3D modellers these days.
- ArtOfIllsion doesn't do Collada, and that's what RepRap is stuck using right now.
but that doesn't exist yet, and even if it's a good file format, it will be a while before programs support it.
So - I think I'd recommend asking people to download every model in AT LEAST STL and Collada - with other formats being permitted as optional extras. Models for which a Collada and an STL are not available should be summararily rejected from the database.
IMHO of course!
-Steve J. Baker
- I think we'll go with a recommendation of something like that, but I don't agree with rejecting anything. For example, the two professional roboticists I know use AutoDesk inventor, so they're probably working in DXF 12, or so. If they want to upload anything, then I want to support them in doing that, even if I have to jump through hoops in order to use what they uploaded. They might dislike and avoid Collada, on the grounds that it doesn't do wire routing, to make up a reason.
- Every problem domain from molecular-visualization to boat-hull design is probably using its own file format and application keychain. We can either be restrictive, in which case many people won't or can't upload anything, or we can be permissive, in which case people upload cool stuff even if it will take us work to make use of it. I favor the latter approach.