1 of 3 DXF files exported with wrong scale

SketchUp
1

Ok, I know any of you reading this will think this is a case of human error, which I think is most likely.

Please give this a review, as I am having a hard time seeing where I could have made the error.

I have three skp files called Pane 1, Pane 2, and Pane 3. Each contains an outline for a pane of glass, and the glass cutting company wants a DXF file.

I export each with (apparently!) the exact same settings, and send the DXF files to the glass cutter.

On install day, Pane 3 is too large by a few inches.

I go back, and open each SKP and DXF file, and I find that for Pane 3 only, the DXF file is scaled exactly 1.05 larger than the SKP file. I can confirm this by importing the DXF file back into the SKP file, and using the scale tool on the imported DXF file.

I’ve combed through the export process (it’s pretty simple! I didn’t change any of the default settings, and to my recall I did not change anything on each of the DXF exports).

I triple checked the model settings in all the SKP files: they are identical.
I used the default 2d DXF export settings, at full (1:1) scale.

A possible answer
The only possible difference I can see is that the camera in SKP file #3 was set to perspective, while the camera for SKP files 1 and 2 are set to parallel projection.

I found this in the help documentation)

This seems to say that, if I export a 2d CAD file with the camera set to perspective, the actual size of the exported model will change!?! This seems absolutely crazy to me as I would never expect that a camera setting could impact the size of the underlying model.

2

This is a common reason for CAD exports to be the wrong size. Set the Camera to Parallel Projection and the appropriate standard view and export it again.

It does because it’s exporting the view of the model.

3

Thanks Dave.

I’m trying to imagine a situation where you would want this behavior? I would never want an unknown scale being applied on export…

4

I can’t think of a reason to want an unknown scale to be applied either but this thing of setting the camera to Parallel Projection for scaled output has been the norm for more than 20 years. It’s the same for viewports in LayOut. You can’t set a scale unless the camera is set to Parallel Projection.

5

It makes sense that a scale can’t be applied in LayOut unless you are in parallel projection, and by extension the same thing is required for 2d export.

I’ve been using sketchup for over 20 years, and this is the first time I’ve run into an exported DXF file not being the scale I expected.

6

Yeah. Me, too.

That’s good.

If you remember to when you could print to scale directly from SketchUp it was the same thing. You couldn’t even set a scale unless you had the Camera set to Parallel Projection.

7

By definition a perspective view cannot be to scale. If the only thing in your model is the outline of the glass pane, you can also use the 3D Model export and the result will be accurate.
Exporting Perspective views to 2D PDF or DWG/DXF is usually used for creating illustration files for postprocessing in another software.