(SOLVED) Can you set (increase) the calculation accuracy of freecad?

[thomas-neemann]

in this example i would expect an intersection to be found. does anyone have a solution?

Bildschirmfoto_2022-09-26_19-43-56.png (47.13 KiB) Viewed 1280 times

1942.FCStd

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[demonlibra]

There are no intersection.
Use Snap Angle or draw extra line from center of circle.

изображение_2022-09-26_224646147.png (4.53 KiB) Viewed 1241 times

изображение_2022-09-26_225004734.png (46.02 KiB) Viewed 1234 times

[thomas-neemann]

...

Thanks for the tip, that works, I just showed a simple example here. but it should also work something like this

Bildschirmfoto_2022-09-26_21-49-55.png (18.17 KiB) Viewed 1228 times

[Roy_043]

The problem is caused by the BoundBox check inside the findIntersection function:
https://github.com/FreeCAD/FreeCAD/blob ... #L107-L113

Quite recently a tolerance has been added, but this is not enough here. The BoundBox of the circle is not as accurate as you would want (or expect) it to be, it is namely based on the polygonal representation of the circle in the 3D view:

Code: Select all

BoundBox (-29.9027, -29.9757, 0, 30, 29.9757, 0)

We need to rethink this portion of the code.

But for now: make the circle smoother:
Angular Deflection = 1.00 °
Deviation = 0.10
The intersection is then found even if the Draft "Internal precision level" preference is set to 8.

The spiral example most likely fails for a different reason as the BoundBoxes of the objects seem to clearly overlap. Please post that file.

[thomas-neemann]

...Please post that file.

thanks for the info, will test it, here is the file

start26sep.FCStd

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edit

it works, thank you very much

[Roy_043]

The start26sep.FCStd file is perhaps wrong? There is no line connected to the spiral.

[thomas-neemann]

The start26sep.FCStd file is perhaps wrong? There is no line connected to the spiral.

yeah that's what it's all about. I'm currently making a video with your information. here is the file

tn2243.FCStd

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[mfro]

The problem is caused by the BoundBox check inside the findIntersection function:
https://github.com/FreeCAD/FreeCAD/blob ... #L107-L113

Just for clarity and to avoid misunderstandings: this isn't caused by any intersection calculation inaccuracy.

FreeCAD does not even try to calculate it because it thinks as the bounding boxes don't overlap the entities can't intersect.

[thomas-neemann]

...

here is the video

https://www.youtube.com/watch?v=D-inGbwiSTU

phpBB [video]

[Roy_043]

FreeCAD does not even try to calculate it because it thinks as the bounding boxes don't overlap the entities can't intersect.

I am aware of that.