Selecting Restricted Areas on Surfaces

[[Er...]]

Frequently, only a particular 'portion' or 'sub-area' of a surface needs to be measured due to the fact that outside this portion the part does not contact its counterpart.

In the CAD software this can be done by drawing a sketch on the surface and make it a 'designated area'. (in Creo terminology, other packages might name it differently)

This area can be exported in the STEP model. You can think of it as a kind of infinitely thin sticker.

The designated area appears as a spotty region on the CAD-model in GOM Inspect:

So far, everything is fine ?

The problem is in the selection of this area. Just pointing and clicking works 50% of the time. Often the whole surface is selected, instead of the designated area.

I worked around this by assigning a unique color to each area and use 'Select by Patch Color'.

This sometimes  takes a very large number of different colors, about 20 in the model that I am presently working on.

Is there some other selection method available? Can these areas be selected in the explorer somehow?

Does it help to import the native model instead of the STEP file?

[[Er...]]

Addition to my previous post:

In some GOM-projects these 'Designated Areas' (Creo term) are visible as 'CAD Bodies' in the sub explorer.

Once they are displayed here they can be selected easily.

The thing is: I don't know how they got there.

[[Na...]]

Hello,

the second screenshot looks like a legacy project (not part based like in 2019+). You can access the same structure with the pen symbol next to the CAD in a part project. Here you could show the designated areas exclusively, select and create a plane for example. They could also be moved into a different part in the project.

Regards,

Nanno

[[Be...]]

Hi,

I'm not an expert for CAD programs but I can give some hints how other customer try to do this:

1. Conservative way: If they want to highlight special areas in their CAD they apply special colors to these patches. Of course, this is only possible if the areas could be colored for unique purposes. Then they select these patches via the 'Select by color' and create a patch compound in our sofware. This patch compound could be used to extract data from the actual mesh for special purposes or these geometrical subset of the CAD could be used in many construction function in our software as a replacement for the CAD
2. Progressive way: A lot of customers now design a measurement plan in their CAD programs. The names are always a little bit different, e.g. FTA, PMI, ...
   This measurement plan is usually based on GD&T as common "language" and therefore it's quite normal that subareas of your CAD are also referenced in the PMI data of your CAD program. We are able to import these PMI information from several vendors and for example a patch compound is automatically created during the CAD import.

One last hint: To create a geometry (patches) twice in your CAD program is usually not a good recommendation and could lead to follow-up errors (in your image you can see that the yellow patch and the original patch are interleaving in the graphical representation).

Hope this helps?!

Regards,

Bernd

[[Er...]]

Thank you Bernd and Nanno.

I tried working with colors, but this turned out to be a bit impractical due to the large number of areas. For repetitive features you would choose one main color, let's say blue, and I ended up with 10 shades of blue. I also tried PMI, but it seems Creo 7 is not fully mature in that aspect.

Eventually, the best workaround was to export the CAD-model twice. First as a solid, then as a collection of patches (surfaces). By storing these in separate parts I can access the patches independently with the pen option (Thanks Nanno!)

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Fully agree, Bernd! Sadly Creo doesn't offer a 100% satisfactory solution for surface partitioning. Creo 'designated areas' are nothing more than surfaces lying on top of the solid. Not an ideal solution really, but acceptable as a workaround.