9 Replies Latest reply on May 13, 2016 12:02 PM by Szalam

    Rendering issue: Light's shadow causing vertical line artifacts

    aland81090138 Level 1

      So I've got two 3D planes next to each other occupying the same Z space but off set in X so there is no overlapping. I've got a camera & light. By animating the light in Z, I get strange vertical lines that appear over one or both of the red planes. Disabling either plane gets rid of the issue. The light is casting shadow and disabling it fixes it but then I lose out on shadows. I'm using the classic 3d renderer and still get the same issue at 8 bit, 16 or float. Increasing the comp's shadow resolution makes the lines thinner but still apparent.  Any ideas?

       

      For anyone who wants to take a look, a simple scene file is here http://bit.ly/1CMX0xq

      verticalLines.JPG

        • 1. Re: Rendering issue: Light's shadow causing vertical line artifacts
          Mylenium Most Valuable Participant

          occupying the same Z space but off set in X so there is no overlapping.

           

          Quantum physics and n-th dimensional string harmonics? This statement makes no sense. Of course they overlap and due to limited precision AE has issues figuring out which is on top of each other. You simply can't do it this way. Pre-compose or offset the planes.

           

          Mylenium

          • 2. Re: Rendering issue: Light's shadow causing vertical line artifacts
            Rick Gerard Adobe Community Professional & MVP

            I looked at your comp. You have a very odd workflow unless this is just for a test. Move either pre-comp 1 pixel in Z and the problem goes away. I'm not sure what production problem you are trying to solve with this setup.

            • 3. Re: Rendering issue: Light's shadow causing vertical line artifacts
              aland81090138 Level 1

              I meant to say there's no intersection. Bummer about the AE limitation.

              • 4. Re: Rendering issue: Light's shadow causing vertical line artifacts
                Rick Gerard Adobe Community Professional & MVP

                It's the shadow calculation that gets things fouled up. Not enough decimal points when both layers are at the same Z and you are diffusing the shadow. It is part of the sub pixel interpolation that AE is using to try and smooth out edges that don't exactly line up with the pixel grid. Set the shadow diffusion to 0 and the problem also goes away. Another way to make the problem go away is to go into your pre-comps and make all of the layers 3D and turn on continuous rasterization.

                 

                Again, I'm not sure what you are trying to do with this comp setup. I can see no reason to pre-compose the Red Solid layer and I do't see any reason in this comp to pre-compose the red solid and the text layer unless you are planning to do something else with the project. It's rare that I would ever pre-compose 2D layers for use in a 3D comp because there are only a few situations where that would be an advantage. If your pre-comps were set up in a more normal workflow as 3D layers and you were using collapse transformations

                • 5. Re: Rendering issue: Light's shadow causing vertical line artifacts
                  aland81090138 Level 1

                  I looked at your comp. You have a very odd workflow unless this is just for a test. Move either pre-comp 1 pixel in Z and the problem goes away. I'm not sure what production problem you are trying to solve with this setup.

                  Yes, it's test to demonstrate the issue of what I now understand to be an AE limitation.

                  • 6. Re: Rendering issue: Light's shadow causing vertical line artifacts
                    aland81090138 Level 1
                    Re: Rendering issue: Light's shadow causing vertical line artifacts

                    Rick Gerard

                    It's the shadow calculation that gets things fouled up. Not enough decimal points when both layers are at the same Z and you are diffusing the shadow. It is part of the sub pixel interpolation that AE is using to try and smooth out edges that don't exactly line up with the pixel grid. Set the shadow diffusion to 0 and the problem also goes away. Another way to make the problem go away is to go into your pre-comps and make all of the layers 3D and turn on continuous rasterization.

                     

                    Again, I'm not sure what you are trying to do with this comp setup. I can see no reason to pre-compose the Red Solid layer and I do't see any reason in this comp to pre-compose the red solid and the text layer unless you are planning to do something else with the project. It's rare that I would ever pre-compose 2D layers for use in a 3D comp because there are only a few situations where that would be an advantage. If your pre-comps were set up in a more normal workflow as 3D layers and you were using collapse transformations

                    Thanks for the detailed explanation Rick. I noticed early on as well that turning down the shadow diffusion to 0 eliminates the issue but also changes the look that has previously been established.

                     

                    This test scene looks like a wacky workflow, sure, so some context is in order: I've created an AE version of a C4D scene that I will hand over as a template to an editor. The scene has several tiles unfolding with the contents of each tile subject to change. The camera move is also subject to change. The PSR info for each tile was baked in C4D and imported into AE via Cineware. PreComposing each tile would make it easier for the editor to drop in video or stills into a tile and allows for them to add little PSR embellishments there than in the parent comp which has the baked C4D keys on it.

                     

                    Seems like I should just do it C4D, right? Yessir that would have been my first choice, but 1) the editor doesn't know C4D to swap textures or animate  2) the added step of exporting videos from premiere and prepping them for use as textures in C4D and 3) the upload/download time for those movies/image sequences for each time the tile content is changed (we are working remotely).

                     

                    Sounds like I'll have to create another set of precomps for each precomp just to workaround this AE limitation

                    • 7. Re: Rendering issue: Light's shadow causing vertical line artifacts
                      Rick Gerard Adobe Community Professional & MVP

                      A single pixel or even a half pixel offset in Z will fix the problem. So would making the original layers 3D and collapsing transformation.

                      • 8. Re: Rendering issue: Light's shadow causing vertical line artifacts
                        blaneg81599181

                        Throw a single 2D adjustment layer in between the two 3D layers and it should sort out your problem.

                        It helps separate overlapping 3D objects for some reason.

                         

                        Why?

                         

                        The world may never know.

                        • 9. Re: Rendering issue: Light's shadow causing vertical line artifacts
                          Szalam Adobe Community Professional & MVP

                          blaneg81599181 wrote:

                           

                          Throw a single 2D adjustment layer in between the two 3D layers and it should sort out your problem.

                          It helps separate overlapping 3D objects for some reason.

                           

                          Why?

                           

                          The world may never know.

                          Because it breaks AE's rendering order (and I don't mean "breaks" as in, "it's messed up", I mean "breaks" like a chef using a knife to break up a carrot - he's making something good with it). A 2d layer thrown in the middle will break ALL 3d interaction. It doesn't matter how far in front in z-space a layer is, if it's below another layer in the layer stack and there's a 2d layer between them, it will appear behind the other layer. This is a very useful feature for solving certain problems. However, if people are unaware of this, it can cause a bit of a surprise.