3 Replies Latest reply on Oct 11, 2012 5:52 AM by PaulFAubin

    Making a trail of blood

    PaulFAubin Level 1



      I am working on a scene where the character has been injured and is crawling along a carpeted area. We are trying to create a trail of blood in the carpet in post. It is tedious work as you can imagine. I have tried to create solids with masks that follow tracking points for the blood stains on his shoe and body, but for the carpet, I am trying to use the paint brush to paint the blood stain. I still need to make it follow a tracking point to compensate for the camera movement. The tracking is working out OK so far. Painting is a little bit cumbersome. Since I have to paint on the layer directly. I really want to paint on a transparent layer on top of the footage (like you can in Photoshop) so that it is easier to make it track the movements of the footage (in other words it needs to stay on the same part of the carpet as the camera shifts around). I found the paint on transparent option, but this makes the footage disappear making it difficult to paint in the correct spot. Working in the paint workspace helps, but again it would be so much easier if I could just paint right in the COMP. (If anyone has suggestions for improvements here, I am open to them).


      Anyhow, what I have not figured out how to do is add a highlight to the blood. If blood were really soaking into the carpet, I think it would catch the light shinning on it and form a highlight area. I tried searching for highlights, and specular, but I cannot figure out how to do it. I am hoping there is a fiter or effect I can run that would create a glint of light on the paint. Any ideas?



      This image is just the begining of the sequence. Later he has crawled much further and I need the blood trail to mark where he's been.

      At the start of the sequence, he is outside on a hard surface like this image. But the rest is on carpet.



      Thanks in advance for any suggestions.

        • 1. Re: Making a trail of blood
          BenjaminMarkus Level 4

          Which version of After Effects are you running?  If you're on CS6, have you tried using the 3D Camera Tracker?  If the camera movements aren't too complex you should be able to use it to create a 3D Camera with 3D track points that match the original movement of the shot.  If your shots can be solved in 3D space then you can attach objects to the 3D track points.  These objects could be red solids with masks that you could animate as your puddles of blood grow larger.  Here's a link to a tutorial on how to use the 3D camera tracker:




          Once you make everything 3D and solve your 3D camera, try playing with the settings and lights in the screenshot below to see if that gets you the spectral highlights you're looking for on your puddles of blood:




          Blood Settings.png 

          1 person found this helpful
          • 2. Re: Making a trail of blood
            PaulFAubin Level 1

            Fantastic. I am running CS6. So I will check out the links you posted and give it a try. Sound perfect though. Thanks so much.

            • 3. Re: Making a trail of blood
              PaulFAubin Level 1

              I watched the first video and I think this is exactly what I need. Thanks very much. I will post when I have had a chance to try it out!