11 Replies Latest reply on Nov 16, 2012 4:10 PM by Rick Gerard

    Starfield. CCparticle World stop static stars from blinking in and out

    Mrocperine

      Ok, so I'm trying to have a simple 3D starfield in the background of my scene. A ship will come into the scene and possibly dive. So my After Effects camera will slowly follow the dive. So, the stars have to move properly to look realistic. Now, as I mentioned the starfield is already setup. But the stars blink-in and then blink-out, a almost twinkle effect. I just want the twinkle to stop. My only problem. Please help.

      CC Particle World. AE CS6

        • 1. Re: Starfield. CCparticle World stop static stars from blinking in and out
          Mylenium Most Valuable Participant

          Simply use larger particles/ custom particles.

           

          Mylenium

          • 2. Re: Starfield. CCparticle World stop static stars from blinking in and out
            Rick Gerard Adobe Community Professional & MVP

            You've probably run into sub pixel interpolation. I'm guessing your stars are very small. A star that's only say 4 pixels aross will flicker as it moves across the screen unless it is moving at exactly whole pixel increments on each frame.

             

            Try this test to see what I mean. Add a vertical or horizontal solid to your composition that is 2 pixels wide then move it 40 pixels in 30 frames. Step through each frame one at a time and observe how the line continues to change size. That's probably what is happening to your star field. Look at what's happening to this 2 pixel wide line as it moves an in partial pixel increments. The screenshot is at 1600%.

             

            subPixelinterpolation.jpg

            • 3. Re: Starfield. CCparticle World stop static stars from blinking in and out
              Mrocperine Level 1

              But how do i get it to just stop? I want complete static in 3D. The stars are very tiny in size yes. But they look perfect the way they are. I would just want them to stop the random going from nothing to fading in, getting bright then fading away and appearing elsewhere and cycling again. I will post what they are doing. heres a link, i uploaded a comp example to show. http://www.youtube.com/watch?v=NiF9Q3ndKh4&feature=youtu.be

              • 4. Re: Starfield. CCparticle World stop static stars from blinking in and out
                Dave LaRonde Level 6

                But how do i get it to just stop? I want complete static in 3D.... heres a link, i uploaded a comp example to show. http://www.youtube.com/watch?v=NiF9Q3ndKh4&feature=youtu.be

                 

                Sorry, but all I see in that video is a title: unwanted blinking.  No stars.

                 

                But if you're moving a layer farther back in z-space, you need to think about what's happening from the camera's point of view: the pixels are getting smaller.  Eventually, they'll be at a size where one pixel is a substantial percent of the star, and any kind of motion -- even on a static starfield -- have big implications for the way the image looks...

                 

                ...and Rick's comments about lines changing white values affects what you're doing.  And you should think seriously about Rick's suggested solution: make your stars bigger.

                • 5. Re: Starfield. CCparticle World stop static stars from blinking in and out
                  Mrocperine Level 1

                  cams not moving nor the star layer. its just sitting there currently. I would actually invite a natural blink when the cam moves. Thats fine. But its the twinkle. You say you cant see the stars in the youtube video, i'll have to repost it. i'll do it in a bit.

                  Oh wait, it does seem like the stars arent there until i fullscreen it. then i can see the stars. please try full screen and see if that works so you can see the stars. thanks

                  • 6. Re: Starfield. CCparticle World stop static stars from blinking in and out
                    Rick Gerard Adobe Community Professional & MVP

                    I watched your video in HD and the stars are there but they are way too small. The blinking looks like a problem with life cycle from particle world.

                     

                    If you're just trying to generate a static star field then I'd make it in Photoshop and import it as a still. If you make two star field layers and scale one then you can create the illustion of flying through space.

                     

                    Here's the formula for a star field in Photoshop.

                     

                    New Image transparent background RGB that's about half the size of your composition

                    Pick something like red and yellow for your foreground and background colors

                    Select Filter>Render Clouds

                    Select Filter>Noise>Add Noise 25% and Uniform and Monochrome

                    Add an adjustment layer above with threshold applied

                    Set your foreground and background layers to black and white

                    Add another layer above your Adjustment Layer and select Filter>Render>Render Clouds

                    Set the top layer's blend mode to Multiply

                    Adjust the Threshold value to build your star field

                    Adjust the opacity of the top Clouds layer to contrl the look.

                     

                    Once you've got the star field you want then save the PSD as a PNG or JPG to flatten the image.

                    Open up the saved flattened star field and scale it up 250% with Bicubic Smoother selected. There's your star field... EZ as pie. The stars are big enough not to cause interlacing or flickering problems, and your comp will render quickly.

                     

                    You could also bring the PSD file into AE as a comp and scale that up 250%

                     

                    You could also overlay colors and add multiple layers blurred copies of the star field layer to give the stars a nice glow.

                     

                         stars.jpg

                    The biggest part of this trick is scaling up the PSD file to make the stars big enough to not cause problems.

                    1 person found this helpful
                    • 7. Re: Starfield. CCparticle World stop static stars from blinking in and out
                      Mrocperine Level 1

                      Thank you i believe its life cycle as well but dont know how to stop it in its tracks. As far as the Photoshop image, i will try that but its still 2D and i like how with Particle world the stars move properly with the 3d camera whether moving forward/backward and sideways. Actually, a 2D starfield was my first attempt. Didnt seem quite right or what i was looking for. This 3D starfield once i've ironed out the kinks will be recycled over and over again in many 3d AE comps in the future.

                      Is there an easy way to stop the life cycle affect? after i enlarge the star size?

                      • 8. Re: Starfield. CCparticle World stop static stars from blinking in and out
                        Rick Gerard Adobe Community Professional & MVP

                        Make 3 photoshop files with different star fields. Make them 3D layers. Position them in 3D space and then fly the camera. They won't flicker, they won't sparkle, and they will look 3D. That's how they did it in Star Wars...

                         

                        If you're moving the camera on the starfield you've created with CCParticle world then you've introduced movement to the starfield layer. That movement and the incredibly small size of your stars is what's causing the flickering. I also don't know how to stop CCParticle World from moving the particles. 

                        1 person found this helpful
                        • 9. Re: Starfield. CCparticle World stop static stars from blinking in and out
                          Mrocperine Level 1

                          Oh wow, I will definitely try that! Thank you very much! I totally didnt think of that. So much simpler.

                          • 10. Re: Starfield. CCparticle World stop static stars from blinking in and out
                            Pierre Devereux Level 2

                            Hi Rick,

                             

                            This looks really interresting, unfortunately, my Photoshop skills leave something to be desired!

                             

                            I am following your steps, but, as embarresed as I am to admit it - I have no idea how to set the foreground and background layers to black and white (firstly) and then when I do seem to get something right, it looks like this:

                             

                            Capture.JPG

                             

                            Not much of a starfield - When I move the slider I am left with "Clumps" of stars.

                             

                            Anyway - sorry to hijack the thread (as I seem so want to do....) but if I can figure this out, it would help a lot of my projects as well, as a nice looking 3D starfield is something I know I am going to have to deal with in the future.

                             

                            Pierre

                            • 11. Re: Starfield. CCparticle World stop static stars from blinking in and out
                              Rick Gerard Adobe Community Professional & MVP

                              Try going into your bottom layer and adding more noise. Then readjust the threshold. Change the default colors to black and white (click the little box at the top left of the colors in the tool bar) and re render your clouds layer on the top. Set that layer to multiply and adjust the opacity.