Quilt merge intersect unexpected behavior

Forum|Forum|3 years ago
September 7, 2022
1 reply
2808 views

I have some basic geometry that when merged presents different solutions based on the order in which the merge reference quilts are selected. I am not able to explain this when considering the boolean logic resultant from the set intersection. 3 Unique solutions are available depending on the order in which the merge reference quilts are selected.

Can anyone offer an explanation as to why this is the case? See the video for a detailed explanation of my observations. Creo 7.07.

(view in My Videos)

Surfacing

T

Tdaugherty

16-Pearl

Maybe this is helpful? It seems that the first quilt in the list is the parent quilt (the one you're modifying). The subsequent quilts are the ones that you use to modify the parent quilt. In my experience, this logic seems consistent with the other merge commands in Creo (component operations > boolean > merge, data doctor merge).

http://support.ptc.com/help/creo/creo_pma/usascii/index.html#page/part_modeling%2Fpart_modeling%2Fpart_three_sub%2Fto_merge_more_than_two_quilts.html%23

I recommend using the preview that is mentioned here (#3). It's very helpful to see what the merged geometry will look like.

tbraxton

Author

22-Sapphire II

@Tdaugherty thanks for the reply. The support article does not address what I am looking for. I am able to get the desired geometry in this case. The issue is that the resultant geometry is different depending on the order of the references and I do not think that should be the case.

I should add some context to this inquiry. It is driven by me being frustrated by some undesirable behavior in models when modifying them. I have recurring issues with surface normal vectors of draft features being reversed and the direction of merge intersections being flipped without user input. This results in lost productivity in the design process. Manual verification of these issues is quite tedious in the models I typically deal with.

I am trying to understand exactly how the algorithm works for merge (and draft) when determining the directions. If it is predictable then I can attempt to build the models such that they are more robust and avoid this unpredictable behavior when editing models.

Consider this geometry and compare the results to my test model above. There are 4 unique solutions here as I would expect and I can generate all 4 regardless of which reference is selected first. i.e. if one reorders the quilts, the resultant solution does not change. This is not the true for my test model in the original post.