How to make a radial gradient around image or movie?



  • I've been trying to come up with a way to make a radial gradient around a movie in Isadora. It seems like I should be able to do it with some of the QC or CI actors (I'm using v2) but I can't seem to get them to display video.

     Basically, I'm trying to make it so that media within the bounds of the projector doesn't have hard edges. So if there's a way to apply blur to just the edges of a projector... or... suggestions? 
    I was looking at making a gradient mask in photoshop, but I couldn't seem to get that to work right either. I think that's probably the right way to do it, but I'm not sure which masking actors and settings will get the right blending going on.


  • I would do this with two movie files. On is the movie you want to project and the other is a very short(no more than 1sec long) solid color movie with a transparent part in it. You encode it with alpha channel (millions of color+ or RGB+) into PNG, ProRes or HAP. Then you will mix it in Isadora where the movie with the transparency lays on the top.

    There are some trix to produce this mask without gray/white pixels on the edge. Some years ago there has been lots of talk about this also on Modul8 forum.


  • awesome, thanks for the hint! That makes sense. I'll see what I can find on the modul8 forum.



  • Here is a sample how to set it up in Isadora 134a6c-alpha.zip



  • works beautifully, thanks!



  • @ tadakan,

    i always use the shape actor. i can change the shape, size and blur of my mask according to my needs. just take a look at the attached file if this is what you are looking for.

    3aae84-mask.zip



  • i would use a bit of cardboard and some gaffa.



  • @dbini

    this is a solid advise. I have done this as well. Specially if I can not afford loosing CPU power to playing transparencies and specially for using blurs(otherwise gapworks sample is the most easy one).
    Or when layer stacking gets too complicated.


  • @dbini I prefere aluminum tape, more safe -,-



  • thanks @gapworks! also a great suggestion. I didn't realize that the mask actor would correctly interpret a shape.

    I made a semi-snarky comment the other day about how Isadora is like a video game with hidden achievements: there is usually a way to do what I imagine doing, and it often involves actors I haven't used, frequently named slightly differently than I would have named them.
    I was aware of the potential for physical masking, but in this particular scenario it won't work. I want to take the hard edges off of stuff so that I can play multiple pictures and movies on a large screen (roughly 26'wide x 9'tall ~8m x 3m) I'm trying to avoid pre rendering video so that I can flexibly change positioning of stuff when I get to rehearsal.
    Thanks again everyone! 
    Tom


  • I just tried both methods with the same video clip behind the mask and on my 15" 2.5ghz i7 MBP with 16gb ram and 750M 2gb the video mask actually seems to be a little bit easier on the resources. One instance is running roughly 30cycles (sometimes more) faster that way than the with the shape actor method. The shape actor method also drops down to about 18fps when I have safari open. It can maintain 29.5-30 when Izz is the only thing running.

    The difference in GPU vs CPU rendering (forced by shapes and mask actor I think) is enough that I'll probably start out with building my scenes using vanakaru's method. It would be nice if we had a shapes and mask actor that were gpu compatible, being able to edit the mask quickly would certainly be handy.

  • Tech Staff

    Not sure if this would be a solution for you but I know that I have seen a vignette FFGL, maybe some searching would turn it up.



  • I used an Iris from a light attached to a metal arm coming off the projector. It was great reliable and the iris is adjustable. This was for a tour with a lot of other things to setup. The arm and iris meant that setting the "circular mask" each show was a 2 minute job.


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