dimension incorrect value in 3D view

Discussions about the development of the TechDraw workbench
Forum rules
Be nice to others! Respect the FreeCAD code of conduct!
frodo
Posts: 3
Joined: Wed Dec 01, 2021 4:55 pm

dimension incorrect value in 3D view

Post by frodo »

For some reason the dimensions in the 3D view in TechDraw show the wrong dimensions. The correct ones are 27 and 60. The factor of error is approx. sqrt(1.5). I added a screenshot where the bug is visible.
Attachments
Schermafbeelding 2021-12-01 180256.png
Schermafbeelding 2021-12-01 180256.png (42.87 KiB) Viewed 3069 times
jmaustpc
Veteran
Posts: 11207
Joined: Tue Jul 26, 2011 6:28 am
Location: Australia

Re: dimension incorrect value in 3D view

Post by jmaustpc »

Your first post, welcome to FreeCAD.

You are measuring the projected edge, which of course is different to the real edge. There are some properties you have to change. Read the wiki, I think it's all explained in there. I am on my phone and in a hurry I have to get one of my kids to her final high school exam here in the Australian outback. Exciting time for her!! :)

Jim
domad
Veteran
Posts: 2051
Joined: Mon Jun 22, 2020 12:16 pm

Re: dimension incorrect value in 3D view

Post by domad »

Hello, greetings to the Community!
...... I add https://forum.freecadweb.org/viewtopic. ... &start=70
frodo
Posts: 3
Joined: Wed Dec 01, 2021 4:55 pm

Re: dimension incorrect value in 3D view

Post by frodo »

Thank you.
The wiki was a good start, but this guy also helped out.
https://youtu.be/z3w84RfvqaE?t=250

I get that this works, but why can't this standard factor just be integrated in all isometric views?
chrisb
Veteran
Posts: 53919
Joined: Tue Mar 17, 2015 9:14 am

Re: dimension incorrect value in 3D view

Post by chrisb »

frodo wrote: Wed Dec 01, 2021 9:11 pm why can't this standard factor just be integrated in all isometric views?
Not sure, if it can't be done. The point is, that it isn't implemented yet, but helping hands are always welcome.

I have learned here, that in technical drawings only the lines in the projection plane are to be dimensioned.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
User avatar
wandererfan
Veteran
Posts: 6265
Joined: Tue Nov 06, 2012 5:42 pm
Contact:

Re: dimension incorrect value in 3D view

Post by wandererfan »

frodo wrote: Wed Dec 01, 2021 9:11 pm I get that this works, but why can't this standard factor just be integrated in all isometric views?
There is no easy way to know which edge in the 3D model corresponds to a given edge in a drawing. An edge in the drawing may not even have a corresponding edge in 3d (ex the circumference of a sphere).

People can do this easily, but you would need a geometry AI to do it with code.
chrisb
Veteran
Posts: 53919
Joined: Tue Mar 17, 2015 9:14 am

Re: dimension incorrect value in 3D view

Post by chrisb »

Hi Wandererfan, good to hear from you!
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
jmaustpc
Veteran
Posts: 11207
Joined: Tue Jul 26, 2011 6:28 am
Location: Australia

Re: dimension incorrect value in 3D view

Post by jmaustpc »

frodo wrote: Wed Dec 01, 2021 9:11 pm I get that this works, but why can't this standard factor just be integrated in all isometric views?
Just thought I would let you know that Wandererfan is the developer who wrote most of TechDraw WB, since being new here you wouldn't know.

wandererfan wrote: Sat Dec 04, 2021 6:00 pmping
G'day Chris! :)
Jim
user1234
Veteran
Posts: 3328
Joined: Mon Jul 11, 2016 5:08 pm

Re: dimension incorrect value in 3D view

Post by user1234 »

frodo wrote: Wed Dec 01, 2021 9:11 pm I get that this works, but why can't this standard factor just be integrated in all isometric views?
Because the norm says, the the default measures are projected. For example this:
0.png
0.png (19.73 KiB) Viewed 2689 times
If an edge is slanted, you always get false results.


Gotcha, this part is slanted in 3D!
1.png
1.png (18.67 KiB) Viewed 2689 times
So the default must be projected, because the part can be orientated in the room anyhow, also random isometric, else you do not know what you get. This does not mean, that others are not allowed, the others are just not the default.


Greetings
user1234
Post Reply