2 points and use the one that it's the highest in a direction

[[Ma...]]

If I have 2 (or 3) points that in the CAD are on the same Z, but in different surface in the same CAD, and I want to use in the aligment the measured point that have the highest coordinate in (for example) Z direction, it's possible?

This is necessary because in a stage project it's possible that some cavity has the highest point A and some other has the highest point B (see image below).

[[Na...]]

Hello Marco,

the highest Point can be detected with a touch point disc (on selection):

https://techguide.gom.com/en/article/cmd_primitive_create_touch_point_disc_on_selection.html

The selection would be the area of the two points. What kind of alignment is it? 

Regards,
Nanno

[[Ma...]]

Hi, thank you for your response! I know the touch point disc (on selection), but in this case I can't use it because the surfaces are too small and I have to use interection point. There are not other possibilities? Thank you very much.

[[Na...]]

Another approach using the touch point disc: 

• select both nominal intersection points, right click -> select all points of element
• Construct -> Point cloud -> Discrete point cloud from selection. This will give you a point cloud consisting of the two points
• Construct a touch point disc with a big enough radius to span over both points -> right click on point cloud and select all points

Just realized it's a bit complicated to write down so here is a video 🙂 The alignments I created represent the stages in your case.

 

Regards,
Nanno

 

[[Ma...]]

Thank you very much! I think the solution is very good, but it doesn't work fine. See images below.

 

[[Be...]]

Hi,

without the concrete data it's hard to give a good hint but the following could have happened: The introduced rule with the 'Touch disc' is a so called static rule which means that no iterative calculation of this disc could be applied during the RPS calculation. This means the surface points are used as fixed points. But if the part is moving in x and y  due to the other rules in your RPS the intersection surface point can change, but for the calculation only the computed coordinates of the surface points are considered (calculated in the parent alignment).

If this could be the reason, you should think of a hierarchical alignment: In the RPS alignment you can introduce both surface points as rules in Z as dynamic rule. And then you have to create a dependent further RPS alignment which is constrained only for moving in the Z-Direction with the 'Touch disc rule'.

Hope this helps?!

Regards,

Bernd

[[Ma...]]

I tried and it gets better (not perfectly, error of 0.01/0.02 mm in some cavity), but I don't understand why I have to do 2 aligment for do this and the result anyway it's not perfect. I think GOM it's a spectacular software, but the only achille's heel are the alignments. Sometimes it's not possible to obtain what I want in a easy way, but only with different action like this. Mine it's a suggestion, improve the alignments. I had problems in the past, and this problems were not be solved because GOM can not do the alignments i want. In this case 0.02 mm of errors I think can not be accettable.

[[Be...]]

Hi,

again, if you have a concrete data problem you can contact the professional support via your local GOM partner in your country. Without the data we can't see what you really have constructed inside your project and the 'Forum' is not the right place to discuss concrete data problems. In my example dataset the deviation is zero as expected therefore it's hard to guess what you have done differently. Please contact your local GOM partner and supply your concrete data!

Regards,

Bernd