11 Replies Latest reply on Apr 2, 2013 2:46 PM by SeanH_bos

    Need help with masking a time-lapse animation

    SeanH_bos Level 1

      Hi all,

       

      I'm working on a time-lapse project where I have taken 240 shots of a highway heading into my city, and have erased the cars from the shot, creating the look of an "empty city". This will be one of many sequences like this.

      I got the highway background plate perfect, no cars, and I threw that into my AE comp (CS6), along with the 240 images as a JPEG sequence. I've layered the background plate on top of the image sequence and used a mask to "hide" the cars from the highway.
      The problem is, some of the cars are taller than the roadway (trucks, busses, etc), so they push into the upper part of the frame where the motion is supposed to happen. If I extend the mask upward, you can see a literal bisection between the still plate and the animated JPEGs. If I just move the mask path to hide cars as they go by, the moving mask becomes VERY obvious in the exported QuickTime.

      I've attached a still of my setup and a short video for explanation. If anyone can help me salvage this shot, I'd be very grateful. I do NOT want to have to erase out the tops of the cars in every photo I took

       

      dorch cars comp.jpg

        • 1. Re: Need help with masking a time-lapse animation
          Mylenium Most Valuable Participant

          I do NOT want to have to erase out the tops of the cars in every photo I took

           

          You may have to. Some things just don't come easy. Generally this is the kind of shot that most people would reconstruct from photos using 3D layers, though, only using the parts from the video that really have motion. It's more or less camera projection stuff as in the respective Andrew Kramer tutorial, just by an order of magnitude more complicated....

           

          Mylenium

          • 2. Re: Need help with masking a time-lapse animation
            Dave LaRonde Level 6

            I don't know if you even NEED an image sequence, judging by that video.  If you get rid of the vehicles on the exit ramp, you're left with a static image, correct?  why not just use what you have to build a clean plate including the portion above that guard rail?  If you feather your masks, things should be fine. 

             

            Two bonuses:  you won't have the atmospheric distortion in the current movie.  You shot on a long lens, yes?  It accentuated the distortion.  The second bonus: you wouldn't have to stabilize the minor jitter in the shot.

            • 3. Re: Need help with masking a time-lapse animation
              SeanH_bos Level 1

              Dave LaRonde wrote:

               

              I don't know if you even NEED an image sequence, judging by that video.  If you get rid of the vehicles on the exit ramp, you're left with a static image, correct?  why not just use what you have to build a clean plate including the portion above that guard rail?  If you feather your masks, things should be fine. 

               

              Two bonuses:  you won't have the atmospheric distortion in the current movie.  You shot on a long lens, yes?  It accentuated the distortion.  The second bonus: you wouldn't have to stabilize the minor jitter in the shot.

              I actually do have a clean background plate, that's the topmost layer in AE. There is no exit ramp, what you're seeing for cars are the tops of them not hidden by the mask. They're part of the image sequence.

              Not sure what you mean by "use what you have to build a clean plate including the portion above that guard rail?" I already have a clean background plate with no cars, are you saying I should feather the mask I already have to eliminate the tops of the cars that are showing through?

              I did shoot through a telephoto lens, though I didn't think that was causing distortion. Looks like heat waves to me, no?

              • 4. Re: Need help with masking a time-lapse animation
                Dave LaRonde Level 6

                As Mylenium wrote, you'll just have to build it.  The result will be a static, no-motion plate.  So build it out of those 240 images you have.

                 

                No one said this stuff was going to be easy.  Remember, Rhythm & Hues went bankrupt within days of winning an Oscar for Life of Pi.

                • 5. Re: Need help with masking a time-lapse animation
                  SeanH_bos Level 1

                  Dave LaRonde wrote:

                   

                  As Mylenium wrote, you'll just have to build it.  The result will be a static, no-motion plate.  So build it out of those 240 images you have.

                   

                  No one said this stuff was going to be easy.  Remember, Rhythm & Hues went bankrupt within days of winning an Oscar for Life of Pi.

                  That's not a solution for me. I'd prefer to just reshoot it from a different angle/location.

                  As I said before, I already *have* a static, no motion plate. The project is to show time lapse motion video scenes, with cars & people erased. So the roadway should be static, but the sky, lights, billboards, etc, should all be moving.

                  I think the way I shot this clip, I'd have to erase the cars above the guard rails photo-by-photo to get a time lapse completely clean of cars. But that wouldn't solve the lens distortion or whatever is going on from shot-to-shot.

                  Might be the best way to approach this project is just shoot everything with the standard wide-angle and a higher shutter speed.

                  • 6. Re: Need help with masking a time-lapse animation
                    Dave LaRonde Level 6

                    The project is to show time lapse motion video scenes, with cars & people erased. So the roadway should be static, but the sky, lights, billboards, etc, should all be moving.

                     

                    Well, good luck.  This isn't the simplest thing in the world to do. 

                     

                    For example, it will be EXTREMELY difficult to maintain proper exposure on a day with broken clouds in the sky: sometimes things will be in shadow, sometimes they won't... and you'll need to build a time-lapse while eliminating the things you don't want in the time-lapse while the shadows of clouds mess up your shots.

                     

                    I suspect you're attempting this because you've never seen it done.  There's a reason why you've never seen it done, as you are learning.

                    • 7. Re: Need help with masking a time-lapse animation
                      SeanH_bos Level 1

                      Dave LaRonde wrote:

                       

                      The project is to show time lapse motion video scenes, with cars & people erased. So the roadway should be static, but the sky, lights, billboards, etc, should all be moving.

                       

                      Well, good luck.  This isn't the simplest thing in the world to do. 

                       

                      For example, it will be EXTREMELY difficult to maintain proper exposure on a day with broken clouds in the sky: sometimes things will be in shadow, sometimes they won't... and you'll need to build a time-lapse while eliminating the things you don't want in the time-lapse while the shadows of clouds mess up your shots.

                       

                      I suspect you're attempting this because you've never seen it done.  There's a reason why you've never seen it done, as you are learning.

                       

                      Um, I never said it was easy, and I have been successful in other shots. This was one where I got stuck. This is a new process for me and yes, I'm learning.

                      I come to these forums to learn and get help from others who've perhaps done what I'm trying to do.
                      I don't come here for cynical, gloom-and-doom posts. If you don't have a solution, there's no need to post negative comments.

                      And for the record, I have seen it done. YouTube the Empty America series, you'll see what I'm trying to do.

                      • 8. Re: Need help with masking a time-lapse animation
                        Dave LaRonde Level 6

                        A lot of planning went into those shots. 

                         

                        You'll note that in many of them, the things that move -- clouds in the sky, for example -- can easily be masked, and they were shot time-lapse over a short duration of time.  In other shots, the sun wasn't an issue: it was cloudy or it was night.  Others were assembled shooting in real-time with masking, and again, changing light angles would not have been an issue. 

                         

                        There are a lot of different techniques used in those things.  It's interesting to note that at this web site, the photographer/editor/VFX practitioner only mentions some of them: particularly the use of clamps instead of tripods.  He doesn't give away many of his tricks.

                         

                        I presume you've doped out how the zooms, pans and tilts were done.

                        • 9. Re: Need help with masking a time-lapse animation
                          SeanH_bos Level 1

                          Dave LaRonde wrote:

                           

                          A lot of planning went into those shots. 

                           

                          You'll note that in many of them, the things that move -- clouds in the sky, for example -- can easily be masked, and they were shot time-lapse over a short duration of time.  In other shots, the sun wasn't an issue: it was cloudy or it was night.  Others were assembled shooting in real-time with masking, and again, changing light angles would not have been an issue.  

                           

                          There are a lot of different techniques used in those things.  It's interesting to note that at this web site, the photographer/editor/VFX practitioner only mentions some of them: particularly the use of clamps instead of tripods.  He doesn't give away many of his tricks.

                           

                          I presume you've doped out how the zooms, pans and tilts were done.

                          Easily masked is I think where I got tripped up. In the Golden Gate shot, for example, it's pretty much a straigh mask up the center of the shot. In mine, there are curves with lots of buildings right next to the highway. Poor choice of location, perhaps.

                          Yes, Ross definitely doesn't share a lot of how-to, mainly just erasing objects and layering in After Effects. How he deals with problems/challenges isn't covered, so that's my learning curve.

                           

                          The zooms are easy, you can do that in post if you shoot high enough resolution. The pans were done on a pocket dolly using a remote device that automatically tracked the camera across the scene over time. Couple hundred bucks to rent one, but too advanced for me at this point. I'm more concerned with getting stable, usable shots.

                          • 10. Re: Need help with masking a time-lapse animation
                            Dave LaRonde Level 6

                            The pans were done on a pocket dolly using a remote device that automatically tracked the camera across the scene over time. Couple hundred bucks to rent one, but too advanced for me at this point. I'm more concerned with getting stable, usable shots.

                             

                            Surprise!  They were just shot at the resolution of an image sequence -- which can be much higher than HD -- and the position was animated. You'll note the pans don't go very far, so it's easy to do with existing resolution.  The same trick works for tilts.

                            • 11. Re: Need help with masking a time-lapse animation
                              SeanH_bos Level 1

                              Dave LaRonde wrote:

                               

                              The pans were done on a pocket dolly using a remote device that automatically tracked the camera across the scene over time. Couple hundred bucks to rent one, but too advanced for me at this point. I'm more concerned with getting stable, usable shots.

                               

                              Surprise!  They were just shot at the resolution of an image sequence -- which can be much higher than HD -- and the position was animated. You'll note the pans don't go very far, so it's easy to do with existing resolution.  The same trick works for tilts.

                              No, actually in most of the videos, especially the Seattle one, Ross used a pocket dolly and a remote control. If you watch the making of for Seattle, he explains how he did the panning shots.

                              But yes, if you shoot hi-res JPEG, you can scale it up and then pan and zoom as you like.