show colour deviation representation error?

[[Gá...]]

Dear development team,
I would like to inform you that after trying several different software versions (2022, latest 2023), we have noticed a wrong display of the "Display"-"Show color deviation representation" function on the right side of the screen in several different GD&T evaluations.

Page 3
The error is reproducible on GOM test pieces, for example in the case of line profiles the direction of the arrows is opposite to the value and colour of the deviation labels. For a deviation of +0.07, indicated in red, the red arrows should appear outwards from the surface. 

Page 4
In the case of flatness, at -0,03 deflection mark at the top centre, the blue arrows should point inwards into the material.

Please check and correct in the software.

With thanks
Gábor Tóth

Visualization_error.pdf

[[Gá...]]

[[Gá...]]

[[Ch...]]

Hi Gábor,

The surface comparison on CAD that you show in the first page is entirely alignment dependant, and is also going to change slightly depending on the quality of the CAD - importing the CAD as low quality vs high quality will show slightly different results due to the way the comparison is calculated.

The difference you are seeing in the last page with the flatness is because flatness does not care about location or orientation - it is purely a form measurement. This means that the calculated plane is allowed to move around to minimize to deviations. There is also the fact that the prealignment takes into account all of the CAD and mesh data, whereas the flatness only considers the data that makes up the plane.

Take a look at this surface comparison, where, in the prealignment, we compare the surface to a gaussian best fit plane and its flatness colormap - we definitely see a difference. 

 

Now let's do the same comparison, but with a plane calculated using the Chebyshev middle fitting algorithm

 

[[Ch...]]

My apologies, I realized that I read through your post too quickly.

As for the direction of the vectors, I do believe this by design and to indicate the direction the material needs to move, not to reflect where it is.

[[Gá...]]

Hi,

Thank you for addressing the issue.
However, still in the first description I wrote the direction of the arrows is not correct. I think this is a bug.

[[Ja...]]

The arrows in positional check representations are a bit confusing i must admit.  My interpretation is that they show the direction your actual tolerance zone needs to move in to meet the target.  I think it would be nice to have a toggle on the representation style as mostly you would expect it shows the direction of material/ zone movement .

[[Gá...]]

Hi James, Thank you!

Such an interpretation is possible, but in the measuring software I know so far it works the same way as the "Surface Comparison" in the case of GOM/ZEISS.
That is, excess material compared to the nominal surface should be indicated in the + direction in red and with a positive value. 
This works perfectly for Surface Comparision. 
For example, it does not work correctly for the GD&T flatness listed.

Page 3

The error is reproducible on GOM test pieces, for example in the case of line profiles the direction of the arrows is opposite to the value and colour of the deviation labels. For a deviation of +0.07, indicated in red, the red arrows should appear outwards from the surface. 

Page 4
In the case of flatness, at -0,03 deflection mark at the top centre, the blue arrows should point inwards into the material.