RE: File Format for RP

From: Justin R. Kidder (
Date: Mon Jun 01 1998 - 20:42:06 EEST

I think this is an interesting thread, because so many people have
problems with STL, but it seems that the RP companies don't seem to care
too much because they have a lot invested in sticking with STL. Some of
the problems mentioned so far this week:

- too many triangles are needed for high resolution models
- since STL is redundantly redundant ;) these files get TOO BIG!
- no topology information included
- no support for color (this may be important someday soon)
- ...

I'm interested in knowing what else people think is bad about STL, either
in terms of specific features (support for "X") or in terms of more vague,
"I wish an STL file was/had..." type answers. I will try to compile the
wish list and post back with a comprehensive list. Someone mentioned a
while ago something about the need for a "3-D Postscript" to replace
STL...let's try to find out all the things it should do! And remember,
look to both the present and future of RP for features to include...


On Mon, 1 Jun 1998, Denton, Karl R. wrote:

> Al,
> Agreed! I now spend more in file space (files with several million
> tri's) in order to get our stl files to a resolution high enough that
> the triangulation will not show through on our Sanders equipment. Truly
> a more efficient file would help Williams International.
> Karl
> -- [ From: Al Hastbacka * EMC.Ver #2.5.3 ] --
> Someone Who Is Looking for a New RP File Format,
> The present STL format is enough in accuracy for the present RP
> processes with dimension forming accuracy of 0.25mm. STL is still simple
> , effective and easy to process.
> As a rebuttal to this comment, the following is my opposing position.
> In some of our advanced development efforts, the hardware is more
> accurate than the STL file. Therefor, it would appear that a new file
> structure or type is needed.
> Regards,
> Al Hastbacka

Justin Kidder, Research Asst. | Automation and Robotics Laboratory | University of Pittsburgh
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