07_fight cloud

This was a video project that involves what i’m calling ‘long exposure video’. Nothing was exposed for a long time, which is meaningless in terms of video cameras which are constantly on, but once filmed the individual frames were combined algorithmically in various techniques which serve to smear the image in an analagous way to long exposure photography.

I’ve always been charmed by fight clouds in comics.
Here’s one i drew earlier. I wanted to recreate this on film. It should slowly churn.


The basic method

1. Film myself and a couple of friends fighting against a green screen.
By fighting we were throwing punches and kicks in slow motion.

2. Remove background and Chroma Key away the green area.

3. Fade each clip in and out and slowly rotate it through 1080 degrees over one minute.
Each clip had to be shrunk by 75% to avoid the edges. all this was easily done in the powerful
Premiere CS3. Export out as an image sequence – images compressed as JPEGS.


4. Now i have 10 folders of 1500 frames (720*576pixels) of rotating action against black. Each folder is a different person/outfit. The first 5 rotate anticlockwise, the last five clockwise. These are then manipulated using a Java program. The program loads up each frame as a RGB array and then places the pixels onto a new movie-clip, each frame moved along from the previous. The many different pixels which pass over any single point are combined in a number of different ways until the right effect is achieved.

Rule 1 – Average

Each new film pixel is the average of all the non-black pixels which passed through this point. this serves to grey out the middle of the cloud, and leaves the outer edges (where the fists and boots are flying) more colored + detailed, hopefully.


OK got my head around the code involving moving one image sequence around another larger one, where it bounces at the ends back and forth. Some of the debugs done on this:

1) remember to seperate the RGB into three ints (0-255) before averaging
2)&3) check the images to be averaged. in this case large areas around the figures looked black (0,0,0) but were actually slightly off coming out of the Premiere ChromaKey process (up to 8,0,4). theses were thresholded – so any pixel with r*r+g*g+b*b>300 are treated as colored and averaged. before everything was getting averaged with 9 other off black pixels resulting in these dark images and over-flooded sections.
4) this was what i was aiming for with each of the 10 different sequences
5) too much symmetry due to all images starting from their frame 0.
6) corret output with 100 sequences layered
7) 200 sequences layered

this last one took a few minutes on its own so to output the entire sequence of 1 minute (=1500 frames) is an overnight job.

The cloud effect is good. Will probably over edit in some figures which stick out more, but less of them. Need to reshoot everything with a better green screen which doesn’t chop off the feet.

Reminds me of a Guston image which is good as he’s one of my favourite artists – definitely need bigger boots.
The cloud will be slowed down and fade in and out in an ever repeating brawl.


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