.STL: non-closed manifold surface
Hi foamers i'm in trouble with my .stl file. I need to extract the feature of my surface but OF recognizes a non-closed manifold surface.
I tried to fix the surface with admesh, but, although admesh not find more errors, surfaceFeatureExtract doesn't work! Any hint? Thank you |
Greetings Giulio,
AFAIK, you've got two more applications that might help you:
Best regards, Bruno |
Thanks Bruno.I tried but i can't manage. I tried netfabb (http://www.netfabb.com/) too but no improvement.
It's strange because all those tools recognize that my surface is closed! In the worst case they find some holes but can fill them and so fix the surface. Nevertheless OF can't extract the features because of the absence of closure! I don't what else to do... |
Hi Giulio,
My guess is that there might be overlapped surfaces... Nonetheless, OpenFOAM has several tools that can help you. If you type surface in the terminal and press the Tab key a couple of times, a list of applications should appear. Here are the ones that might help you: Code:
surfaceAutoPatch Best regards, Bruno |
Thanks a lot Bruno!
I'll try and i'll let you know! |
I tried with surfaceCheck.Here the log:
Code:
giulio@giulio-System-Product-Name:~/OpenFOAM/giulio-2.1.0/run/sistema_aspirazione_prova1/constant/triSurface$ surfaceCheck sistema_aspirazioneSPLIT.stl I can read this Quote:
Worse yet is that surfaceFeatureExtract recognizes not closed surface...what do you think about Bruno? thanks for your help |
Hi Giulio,
OK, there are a few indications that not everything is sane in this STL file:
Best regards, Bruno |
surfaceSubset (or my brain) doesn't work!I didn't understand if i have to launch
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Thanks a lot P.S. i can also attach the .stl file if you want to check!! |
Hi Giulio,
Indeed, without an example STL file, it's complicated to figure out how things should work. Additionally, I can cross check with a recent build of OpenFOAM 2.1.x, to confirm if this is something that has already been fixed or not. Don't forget to compress the file before attaching. If the package is larger than 97~100kB, then you better use some other file sharing system, such as Dropbox. If the content of the file is sensitive, you can always send the link just to me via private message. By the way: what about those OBJ files? Have you checked where the floating/disconnected triangles are? Best regards, Bruno |
1 Attachment(s)
Hi Giulio,
OK, so I've given a few trial-and-errors to your 200MB STL :eek: The commands I've used to ascertain what's going wrong are as follows: Code:
#Create a log file with the whole list of errors I've chosen OBJ files as output because they usually are lighter than STL files. Technically none of these commands will fix your STL file; they will only help you diagnose the problem zones. You might have to do some cosmetic surgery on this STL file, to fix those problematic areas. Either that, or reduce a bit on the STL resolution. I've also tried this to join points: Code:
surfacePointMerge sistema_aspirazione.stl 0.0001 sistema_aspirazione_crippled.stl I also tried a couple of times the surfaceClean but with not success. It always crashed indicating that it was unable to collapse certain edges. Example: Code:
surfaceClean sistema_aspirazione_crippled.stl 0.001 0.0025 sistema_aspirazione_clean.stl AFAIK, these kinds of issues cannot be solved with automatic surface fixers. You'll need a powerful surface mesh editor to fix these crazy triangles! Good luck! Bruno |
You are an angel! Thank you very much for all the work you did to help me. I'll try to fix the surface with MeshLab and I'll keep you updated.
thanks again Giulio |
nothing to do ... I do not ever graduate! :D
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Hi Giulio,
Quote:
Additionally, the commands I wrote in the last post provide the triangles that are deemed bad! Whether you like it or not, having to deal with and to fix damaged geometries for using in CFD is part of (almost) every CFD engineer! Additionally, if you could export the original geometry (not the STL) to OBJ file format, it would possibly fix these issues right away! Best regards, Bruno |
I saw you first reply but it didn't help me (maybe because i can't use blender at all).
How could export the geometry in obj help me??snappyHexMesh needs an stl...is it true or am i wrong?? Anyway i exported my geometry in obj!What to do now?How can snappy read obj? Thanks a lot again |
snappyHexMesh can read the OBJ file as if it were an STL file.
Simply modify the file name (and extension) used in "system/snappyHexMeshDict" and it should work as intended. As for Blender, if you have a computer with a Windows installation nearby... you can use the ZIP files, which don't require installation: http://download.blender.org/release/Blender2.49b/ |
Dear Bruno i apologize if i'm annoying you but i had already tried with Blender with no success!
After exporting geometry in .obj i tried to check the surface with surfaceCheck and i ascertained that the geometry is closed (alleluja!) but there are 84 unconnected parts. Checking with paraFoam i saw that there are something like "internal walls" that split the whole geometry in 84 sub-geometry. i tried to modify the snappyHexMesh declaring sistema_aspirazione_*.obj (instead of sistema_aspirazione.obj) to catch all the parts but it doesn't work. I am attaching the link of my .obj so you can check...obviusly if you want!:o (https://dl.dropbox.com/u/87990776/si...losedOK%29.obj) I've got another question: can i use surfaceFeatureExtract on that .obj? Thank you so much for all the help you are giving me and for all the time you're devoting :) |
I won't be able to look at the geometry any time soon, but here are a few hints/details:
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Dear Bruno i removed all the internal faces that splitted my geometry one by one........But no improvements.I also removed inevitably good faces.So now i've got an obj worse than before...but it is possible that it is so hard to get an acceptable geometry?
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Quote:
If surfaceCheck doesn't complain about bad faces, then don't bother with the multiple files. Have you tried using the single OBJ file you've got now with feature extraction and snappyHexMesh? |
Hi, I've had the same problems using surfaceCheck on my .obj file. What I suggest and what removed my badFaces error, is the easy to use program MeshLab. MeshLab is a freeware program available for linux (buggy) and windows (best version imo). It has a clean and repair option that did the trick for me. Hope it helps.
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