17 Replies Latest reply on Jul 23, 2018 1:16 AM by Damir Galic

    Strange artifacts on part when rendered

    Mark Jackson

      I'm baffled by the strange artifacts showing up on a part when rendered in a model I'm working on. In Preview mode the artifacts don't show, but in Fast and Accurate modes they are there. I've tried a generic appearance with no textures, and I've tried various appearances with textures. The appearance does not make a difference. Could it be some sort of corruption of the part brought in from SolidWorks?

       

      Picture0001.jpg

      ^ Preview mode with Brushed Aluminum appearance applied

       

      Matrix 2501.jpg

      ^ Fast mode render

       

      Matrix 2501 2.jpg

      ^ Accurate mode render

        • Re: Strange artifacts on part when rendered
          Rich Fagioli

          That looks like a "fitting" artefact: where the appearance is, "for whatever reason known only to Visualize", poorly fitted to the part.

           

          Try adjusting your appearance parameters, namely, tiling and mapping method. Manipulating the texture around an axis may also remove this effect. Try fitting the appearance to the part, as well.

           

          I used to get these artefacts too when rendering brushed metal appearances with bump maps. Given the low relative size of bumps in brushed metals, I no longer use "bump strength" and almost always use a specular appearance.

           

          And, no....there is nothing wrong with the SW part.

            • Re: Strange artifacts on part when rendered
              Mark Jackson

              That doesn't seem to be it Rich. Here it is with a generic appearance with no textures at all. Did I understand you correctly that you thought the issue might be textures?

               

              Picture0001.jpg

                • Re: Strange artifacts on part when rendered
                  Rich Fagioli

                  Mark Jackson wrote:

                   

                  That doesn't seem to be it Rich. Here it is with a generic appearance with no textures at all. Did I understand you correctly that you thought the issue might be textures?

                   

                   

                   

                  Yes....That was how I had  resolved this problem (if I can remember that far back): correctly fitting the appearance to the part. I also remember what a PITA it was too because it didn't seem to make sense at the time, as I was doing nothing to the part that I hadn't done to the others! Sorry I can't be more help....

              • Re: Strange artifacts on part when rendered
                Brian Hillner

                Hi Mark,

                 

                Might this be 'z-buffering' you are seeing from co-planar surfaces? If 2 surfaces in Visualize are co-planar (exactly on top of each other), then you will get this jagged artifacting.

                 

                If there's indeed only 1 surface there, then you might try 'Repair' or 'Rebuild' normals - these are buttons in the Models Tab when you have the desired part selected with the blue Part selection tool. This might fix your issue.

                 

                Thanks,

                Brian

                  • Re: Strange artifacts on part when rendered
                    Andreas Olofsson

                    I'd go with Brian's guess. Looks like overlapping geometry.

                    It's happened to me too when Visualize decides to import duplicate parts that were hidden in Solidworks.

                     

                    What I do when that happens is suppress in SW instead of hiding and then re-import to Visualize.

                     

                    Here's a tip for finding the hidden part (assuming you're using Solidworks):

                    Right click anywhere in the empty space of your viewport. Click on the "select" dropdown menu and choose "select hidden".

                      • Re: Strange artifacts on part when rendered
                        Rich Fagioli

                        I've seen this "Z-buffering" artefact before, notably at the plane where two imported (non-treated) surfaces meet. When I have to import multiples of the same part, this artefact will always pop up in some surprising ways; but it's an easy artefact to kill: just move the entire part, or change its scale, or simply delete it. However, the artefact never shows up on surfaces with "properly" assigned appearances, where "properly" means "whatever works". For example, in my project below, I've 3 rendered flanges visible, all of which are of identical overall dimensions. In fact, I could keep exposing new parts until the cows come home and never see this z-buffering artefact, perhaps because a (properly fitted) appearance has been assigned to each surface.

                         

                         

                         

                        As proof, if I delete my appearances, and adjust the opacity of one of my parts slightly, this z-buffering artefact pops up:

                         

                         

                        Now I've applied an off-the-shelf brushed metal appearance to only one part and made both parts 100% opaque. Even if I apply the same appearance to both parts, nothing changes and this z-buffering artefact persists. 15 minutes spent weaking all other texture settings also changes little.

                         

                         

                        However, applying a different, customized appearance that dispenses with a bump texture, and the z-buffering artefact disappears. I won't claim to know why, just that this seems to work for this case:

                         

                         

                        However, even armed with this knowledge, getting to this point still required considerable fiddling with the texture mapping dials. YRMV!

                      • Re: Strange artifacts on part when rendered
                        Mark Jackson

                        That was it Brian. It was a co-planar surface that I was able to find per Andreas' instructions.

                         

                        Thanks very much Rich, Brian and Andreas for the early Christmas present. I love this forum. It saves me so much time and keeps me from getting big headaches! Merry Christmas you guys!

                      • Re: Strange artifacts on part when rendered
                        Lily Martin

                        In Preview mode the artifacts don't show up to you as co-planar surfaces in your artifacts are bipolar to one other.

                        The buttons in Models Tab will fix this issue of z buffering