Why does Simplify always scale a model that is modeled in cm

[SHoutzager]

I get a lot of models that are cm based. Everytime simplify will scale them up 2540%. I will have to reduce it to 1000% and it will be fine.

Is there a way for them to import at the right size if they are cm based?

[horst.w]

here is the solution:

viewtopic.php?f=9&t=6399



horst.w, GER

[SHoutzager]

thanks. But stl files have to have some sort of scale to them that stays fixed, they just dont track whether it is inches, mm, cm.

[horst.w]

... if you believe so, it is ok for me.
But I trust to "Wurstnase"; member of the german RepRap-forum and professional softwaredesigner:

http://forums.reprap.org/read.php?247,7 ... msg-721429

Wurstnase [ Privatnachricht ]
Re: Slic3r zeigt stl "komisch" an ...
07. November 2016 21:41 Registrierungsdatum: 2 Jahre zuvor
Beiträge: 4.802

...
Das STL-Format ist dimensionslos und normalerweise speichert man das in mm ab.
...

Another proof,
when load up a STL-files to an professional printservice like TRINCKLE.com you must declare the right dimension of your object.
That would be not necessary if the stl contains the messure-scale like inch, cm or mm. The stl seams to contain only their values


Regards
horst.w

[dkightley]

Have a read of this: http://www.fabbers.com/tech/STL_Format

In the format specification section: "The StL file does not contain any scale information; the coordinates are in arbitrary units."

S3D assumes that 1 arbitrary unit equals 1 mm.

This is backed up by the prompt box suggesting the imported item may be small and possibly have one arbitrary unit equal to 1 inch, asking if you want the software to scale up the item accordingly from inches to mm.

Check the "models" tab of the General Options in S3D. The top flag is "Automatically scale to correct unit system without prompting". Uncheck this to stop the auto-scaling of small sized objects.

[horst.w]

Thanks, Doug!

Every day I can learn anything, it was worth to stand up in the morning.
Today I had my 1st lesson before breakfast


Greetings to Matlock (well known by motorcycle-tours)


horst.w, GER

[pinthenet]

Aha,
I meant to ask about that too. I use Sketchup and I read a tip to size things in meters for better accuracy. I loaded the STL into SD3 without thinking then realised later that the object was sized in mms

Another mystery solved

John

[dkightley]

To be truthful, I wasn't sure if the .stl format file had scale information in it or not....so I took the opportunity to spend five minutes researching on the internet.

I quickly found the linked page...and others...and had a quick read, and then put two and two together to form a conclusion where I could provide the above answer.

As they say....it's not rocket science.


And I wonder where that phrase came from.........

[shi]

If you save your STL in ASCII format, as opposed to binary, you can actually confirm this yourself. The format of STL files is very, very simple. It's just a list of vertices organized into structures like loops and facets, and normal vectors describing the orientation of these structures.

A simple 15mm, 1.5mm, 1.5", 1.5m (you get the idea ) cube would be composed of twelve triangular facets made up of 3-vertice edge-loops, the 6 surfaces of the cube being described by two of these facets per surface. Each facet also has a normal vector, that describes which side of the facet is the "outside".

Like so:

Code: Select all

solid ASCII
  facet normal  0.0  1.0  0.0
    outer loop
      vertex    1.5  1.5  1.5
      vertex    1.5  1.5  0.0
      vertex    0.0  1.5  1.5
    endloop
  endfacet
  facet normal  0.0  1.0  0.0
    outer loop
      vertex    0.0  1.5  1.5
      vertex    1.5  1.5  0.0
      vertex    0.0  1.5  0.0
    endloop
  endfacet
  facet normal  0.0 -1.0  0.0
    outer loop
      vertex    0.0  0.0  1.5
      vertex    0.0  0.0  0.0
      vertex    1.5  0.0  1.5
    endloop
  endfacet
  facet normal  0.0 -1.0 -0.0
    outer loop
      vertex    1.5  0.0  1.5
      vertex    0.0  0.0  0.0
      vertex    1.5  0.0  0.0
    endloop
  endfacet
  facet normal -1.0  0.0  0.0
    outer loop
      vertex    0.0  1.5  0.0
      vertex    0.0  0.0  0.0
      vertex    0.0  1.5  1.5
    endloop
  endfacet
  facet normal -1.0 -0.0  0.0
    outer loop
      vertex    0.0  1.5  1.5
      vertex    0.0  0.0  0.0
      vertex    0.0  0.0  1.5
    endloop
  endfacet
  facet normal -0.0 -0.0 -1.0
    outer loop
      vertex    1.5  1.5  0.0
      vertex    1.5  0.0  0.0
      vertex    0.0  1.5  0.0
    endloop
  endfacet
  facet normal  0.0  0.0 -1.0
    outer loop
      vertex    0.0  1.5  0.0
      vertex    1.5  0.0  0.0
      vertex    0.0  0.0  0.0
    endloop
  endfacet
  facet normal  1.0  0.0  0.0
    outer loop
      vertex    1.5  1.5  1.5
      vertex    1.5  0.0  1.5
      vertex    1.5  1.5  0.0
    endloop
  endfacet
  facet normal  1.0  0.0  0.0
    outer loop
      vertex    1.5  1.5  0.0
      vertex    1.5  0.0  1.5
      vertex    1.5  0.0  0.0
    endloop
  endfacet
  facet normal -0.0  0.0  1.0
    outer loop
      vertex    0.0  1.5  1.5
      vertex    0.0  0.0  1.5
      vertex    1.5  1.5  1.5
    endloop
  endfacet
  facet normal  0.0  0.0  1.0
    outer loop
      vertex    1.5  1.5  1.5
      vertex    0.0  0.0  1.5
      vertex    1.5  0.0  1.5
    endloop
  endfacet
endsolid