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Basic transformation of alignment


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When i do my first alignments i was belived what what it will change orientation, rotation and translation. But its not happen 

So i want to make my coordinate system similar like this: So i want it to be on place chosen by me 


But i have this

and here is is how a made my Alignment 

The origin is somewhere 370..mm under the measured mesh and cad model, i do not understand why




When i'm constructing some theoretical points its look this way: 

and i have to put some crazy values on Z to construct point just over top plane 



I tried to move my origin using alignment by coordinate system, translation. 

Once i "moved" cad or mesh to the ogirin, but one of them stayed where was before.

So when i created nominal elements on cad, program put actual elements not on real mesh but "in air"

Can please you simply explain me how to make sure what my origin is on cad and mesh in same place. So i can construct points in reference to real part, and everything is nice and sweet. 



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quite hard to judge what went wrong only from some images which not show the complete data situation. If you have a valid support contract it might be easier to contact your local GOM partner?!

  1. Have you started with an initial alignment which brings your actual data to your CAD data, e.g. a Prealignment or a 3-points alignment with an additional Local Bestfit?
  2. If you don't see why the Alignment By Geometric Elements  is not working, it makes sense to create a Local coordinate system by Geometric element.
    1. Then you can easier see where the coordinate system element would be placed in regards to your part
    2. This can be done on nominal as well as for actual.
    3. If the data sets are already good enough aligned by an initial alignment, you can create nominal elements on your CAD, apply the measuring principles, create the nominal coordinate system and the actual coordinate system could be created by Referenced construction.
    4. Keep in mind: The created local coordinate systems are not transforming data, but you can use them in the Alignment by coordinate system

Hope this helps to get a clue why your alignment is not working as expected?!



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  • 4 months later...


Thank you Bernd

Your answer it sowed me some things but i need more help. 

I have prealignment made after scan and polygonization

Nominal and actual features  build on this 

i did like you said build the coordinate system - and it not bad becouse it gives me some control about how its created. 

Then i used this coordinated system as aligment and my mesh has "run away from my cad model", - its the part i do not understand it would be good to have i cad and mesh together 

Then i created alignment with geometric elements using the same elements like i usually do 

But its problematic becouse for example when i need to create some line i cannot do based to alignment, but need to do others method what is a lots of clicking 

(also cad comparsions are based on alignments  and it gives me some problem with understand what degres of freedom are taken by witch elements, but its for later i think.)


For me the moust imporatant now is how to make cand and mesh in one alignment. And if it will be made with use of the Coordinate system it will be the best becouse i understand how degres of freedom are restricted in this. 

i tried to find some informations in help but not really sure what should i search for, training is expensive and its not an option at this moment. 

Any basic help appreciated 








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usually you are doing the following steps:

  1. Align your part initially (e.g. via Prealignment)
  2. Construct nominal primitives (cylinder, planes, points, ...) on your CAD or import them via PMI
  3. Apply measuring principles, e.g Fitting element for cylinder/planes
  4. Construct a nominal coordinate system on the according nominal elements
  5. Apply 'Referenced construction' on the nominal coordinate system
  6. Create 'Alignment by coordinate system' where you choose the nominal and actual coordinate system
  7. Last but not least: The alignment via geometric elements is using the same mathematic like constructing the coordinate system elements, therefore you can create this alignment directly, but sometimes it is more helpful to have also the coordinate system as elements, e.g. for checking coordinates under this coordinate system

That's it!

For detailed question with any kind of data dependency (your special project) you have to contact your local GOM partner. A deeper investigation of your special project is not possible via the Forum.

Hope this helps?!


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