Yes, triangles. But thousands of very tiny triangles. The triangle cover the surface of a 3D object just like thousand of tiny rectangles cover the surface of a 2D image. Maybe the analogy with pixels is not perfect but in both cases the ability to edit objects is gone and all you have is thousands of tiny "elements" and not the lines and circles and points you started with.
Technical an STL is a list of triangles where each vertice is given a location in 3D space. Circles and curves are all replaced by polygons. On Mon, Jun 29, 2020 at 6:06 PM Ken Strauss <ken.stra...@gmail.com> wrote: > Are you certain that an STL is " just 3D pixels and has lost all the > lines, > angles, and circles and points that the CAD file had."? I thought that an > STL file was made up of the coordinates of the vertices of triangles rather > than pixels. > > > -----Original Message----- > > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > > Sent: Monday, June 29, 2020 8:54 PM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] I downloaded the latest appimage > > > > It is rare for a CAD program to be able to modify .STL files. In > > Fusion360 there is a way to transform STL back into editable CAD and I > > think Onshape can do the same. > > > > An analogy is that you can edit text with a word processor but if you > take > > a photo of the document with your cell phone, the text is now an image > and > > you would not expect to be able to edit it. STL is like a photo. It is > > just 3D pixels and has lost all the lines, angles, and circles and > points > > that the CAD file had. > > > > Yes there is OCR to take images back to editable text and as said some > CAD > > systems can import STL files back into CAD. STL never translate back > > perfectly even in the best case. > > > > So, Don't give FreeCAD a "fail" for this. > > > > On Mon, Jun 29, 2020 at 1:56 PM Gene Heskett <ghesk...@shentel.net> > > wrote: > > > > > > > > And loaded up the .stl for that half a pulley I tried to make a hub for > > > yesterday, but I didn't get a touch off right and it was about .5mm too > > > small for the plastic. FreeCAD rendered it nicely, but I couldn't get > it > > > to measure anything, nor modify it in any way. > > > > > > So I went back to OpenScad and reworked it. Then exported the .stl, > > > loaded it up into the slicer, set it for super quality, and saved the > > > gcode without all the branding so I got a name short enough to display > > > on the ender's display. > > > > > > So FreeCAD failed its first test here. > > > > > > Cheers, Gene Heskett > > > -- > > > "There are four boxes to be used in defense of liberty: > > > soap, ballot, jury, and ammo. Please use in that order." > > > -Ed Howdershelt (Author) > > > If we desire respect for the law, we must first make the law > respectable. > > > - Louis D. Brandeis > > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > -- > > > > Chris Albertson > > Redondo Beach, California > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
