15 Replies Latest reply on Jun 13, 2012 5:12 PM by Jerry Steiger

    Performance betweed surface model and normal model

    Ari Arponen

      Is there a big performance difference between normal "thickened" 3D-model and surface model? Because I have just a feeling that surface models doesnt rotata as smooth as normal models. Even if its the same part, just made to surface model from normal model.

       

      If you check the attached image, you'll see lots of surface models and its pain in my a**e to make drawings from this model. So would it be better to make those surface models to thickened models? Or does the things get even worse. I hate surface models because its hard to make desent section cuts with them.

       

      Why I started wondering this was that I have original chassis 3D model with normal parts, and for some reason my co-worked converted the parts to surface models. And when i tried to work with the original files it seemed like they worked much faster that surface models. Can someone give little heads up what would be the best solution.

       

      thanks.

        • Re: Performance betweed surface model and normal model
          Jerry Steiger

          Ari,

           

          It seems counter-intuitive to me that the surface model would be slower than the solid model. A face on a surface model is only one surface;The simplest solid, a sphere is also one face. A lens shape would have two. From there you grow to three, like a cylinder; four, like a tetrahedron; six, like a rectangular prism. I would think that it would take a solid model more time to keep track of all the extra faces. On the sheet metal parts that your assembly is mostly made up from it seems like the surface would have roughly twice as many faces to keep track of, as the large front and back faces would generate a lot more triangles than the side faces.

           

          Try timing how long it takes to rotate your surface and solid models a certain number of times.Then you've got some hard numbers to base your decision on.

           

          It would be nice if drawings would show cross section views of surfaces. Since they don't, it seems like a good reason to go with solid models. Plus your solid models would make it easier to get the weight and center of mass of your parts and assemblies.

           

          Jerry Steiger

           

          I see that I garbled my original text when I messed up the editing. It makes a little more sense now, but is still wrong! I was thinking that you had built sheet metal parts with just a midplane surface. It seems like your sheet metal parts have front, back and side surfaces, so they have as many faces as the solid and, as Mark points out, twice as many sides to keep track of, since SolidWorks is smart enough to know that it doesn't need to show the inside surfaces of a solid. I should have noticed all of the parts that weren't sheet metal as well.

           

          Message was edited by: Jerry Steiger

          • Re: Performance betweed surface model and normal model

            Hi Ari,

             

            Yes, your observation is correct. this is something that anyone would notice when they, for instance, import an IGES file but don't chech the options to trim and/or knit.

             

            The reason being is that surface bodies create twice as many faces verses solids to tesselate and display by the GPU - i.e. need to render both sides vs. single side for solid. this also applies to edges in that they are non laminar first laminar causing another ding to graphics performance.

             

            Mark

            • Re: Performance betweed surface model and normal model
              John Burrill

              Ari, it's not a minor thing that the solid bodies on your models have been turned into surfaces.  In addition to th performance drag that Mark talked about, surface models don't have goemtry validation, mass properties and the faces don't have to be trimmed to form a water-tight manifold like the way solid features do.  In your place, I'd investigate the change that made your solids show up as surfaces.  It could indicate an export/import problem or othe geometry error that may keep the part from being producable.

              If the only change in your model turns out to be that it's made of surfaces, then use the knit command to grab all of them and stitch them into solids.

              Good luck.

              John

              • Re: Performance betweed surface model and normal model
                Ari Arponen

                Thank you guys for answers, I had a little chat with my collagues here. They agreed to make the surface models to solid models and we try to make some section drawings after that. But even that we can produce good surface models to our CNC-engineer and moulder. We need some protips to convert the surface models to solid models. I'll attach one of our parts here, which we cannot turn to solid model. I tried knitting it, but when I try to thicken the knitted surface it just wont do it. Which are the problem points here?

                  • Re: Performance betweed surface model and normal model
                    Jerry Steiger

                    Ari,

                     

                    I can't open your part (still on 2010), but I can give you some advice based on my experience. If the Thicken feature doesn't have a check box for "Create solid from enclosed volume", then your surface is not water-tight; it has gaps or openings. The edges that aren't closed will show up with a different color. You can also run the Check feature to find the open edges. If you've got some openings, you can often use a Fill Surface to close them. Sometimes you will need to add some edges, probably with a 3D line or spline, if there is an opening that crosses over a sharp edge. Sometimes you have to rebuild faces that have tiny gaps at the edges.

                     

                    It can all get very frustrating. Sometimes it is better to just rebuild a part in SolidWorks, using the imported part to make sure you aren't deviating too far from the original.

                     

                    Jerry Steiger

                    • Re: Performance betweed surface model and normal model
                      Alin Vargatu

                      Run the Import Diagnostics first. There are a lot of importing errors in your file.

                    • Re: Performance betweed surface model and normal model
                      Ari Arponen

                      newface.jpg

                       

                      Im new to to surfacing modelling, been basicly doing sheet metals all my career. But I think its time to learn something new, but in this point I need to learn how to fix faulty surface models. So up there is the image of two faulty faces. And I think properly way to fix is to make two new faces. How do I make face for that rounded red part? I know that all the edges must be "correct" and that prevents the faulty geometry shown in earlier pic. So I just need to know how to add "edges" to that empty part?

                       

                      edit:

                      okay I got it with help of 3Dsketch. but after I added some surfaces, knitted them (but it still shows some gaps) I cannot use the diagnostics anymore.

                        • Re: Performance betweed surface model and normal model
                          Charles Culp

                          Click on the open edge (blue) and press the delete key. It will ask you if you want to delete the hole, or delete the feature. Pick delete the hole.

                           

                          If that doesn't work (which on the ones you have shown so far it looks like it might not), then you will have to use Insert>Face>Delete, then use the "Delete and fill" function. This should work well on your previous posted question.

                           

                          If worse comes to worst, you might have to delete all of the surrounding fillets, then use the first method above (delete hole). Then recreate the fillets.

                          • Re: Performance betweed surface model and normal model
                            Jerry Steiger

                            Ari,

                             

                            Yes, unfortunately Import Diagnostics is only for imports, so once you add a feature to the model it is no longer available. That is a bit of a shame. It would be nice if you could use the diagnostics and repair tools at any time. Since we don't have that option, use the Check tool to see what problems your part may still have.

                             

                            If you have tiny gaps that you can't fill, you might want to delete the face on one side or the other, using the Delete and Fill, or just deleting and then filling manually, if Delete and Fill fails. Another option is to Offset one face 0 distance, then Delete that same face. Now Untrim or Extend the new Surface and use Mutual Trim to fit it to the rest of the part.

                             

                            Jerry Steiger

                          • Re: Performance betweed surface model and normal model
                            Ari Arponen

                            Geesh.. looks like I have to put my hands up with this. I have managed to make and fix faces to model, but no luck making it as solid. Guess it is too messed up surface model or something. Makes me wanna hang the person who made these. And if I recall right these originally came from some 3rd party design company.

                             

                            The major problem here is that I cannot make section drawings from these part, or is there some way to cut surface models in assembly?

                            • Re: Performance betweed surface model and normal model
                              Ari Arponen

                              Looks like I have to make configurations for section view. Geesh thats frushtrating. I think Im gonna officially hate surface models now.