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Pesky Props

Discussion in 'General Discussion' started by Hughie, Feb 26, 2015.

  1. Hughie

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    What tools and techniques are others using to clip out props in post production.

    I am using a Hero 3+ Black in at 1440 (1920x1440).
    To remove the props basically means losing the top 1/4 of the view which is fine, but tools like GoPro studio / Prodrenalin appear to do this to all edges (basically via zoom) which means I am left with a rather crappy looking centre of 960x720. Not completely sure whether it is the loss in resolution or something else about the generation of the new file, but a lot of quality is thrown away.

    Any clues about how to do this properly ? Perhaps shoot at 2.7K ? Use a different tool, or different technique ?

    Thanks.
     
  2. ianwood

    ianwood Taco Wrangler
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    Switch to medium FOV. Problem solved.
     
  3. Hughie

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    Thanks for the reply ianwood.

    This camera has one FOV in 1440p - Wide. Medium is only available in 720p, 1080p and 2.7K (17:9).

    I will try the top two.
     
  4. newdayoutdoors

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    1080 and 1440 are essentially the same thing in a GoPro. One is 1920 wide x 1080 tall, the other is 1920 wide x 1440 tall. Just 1440 is taller. Same width though. So if shooting 1440 you will want to crop in post to get the typical 1080 project aspect ratio anyway.

    It is explained pretty well in this video by GoPro. https://www.youtube.com/watch?v=HLH5LhGjRLc

    If you want to keep the props and landing gear out of the frame 99% of the time, shoot in 1080 Medium field of view. The tilt of the camera relative to the phantom as it sits level also comes into play. The only time I get props in my image is if I run the gimbal all the way up to 0 degrees tilt down (basically perfectly level with the horizon) and I am moving forward at a fast rate of speed. But I have found, if I set my tilt at 10 degrees below horizontal then I never get props in the footage. Even at 0 degree tilt it is easy in post to remove the props by leaving the bottom of the footage still at the bottom of the frame and up scaling the footage by about 15% ... if that makes sense.
     
  5. Hughie

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    Good points newdayoutdoors. I will go for the 1080p option, that way I get to keep some control over framerate too.
    Thanks.
     
  6. PTCX

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    An ND filter (Neutral Density Filter) will help to make the props less visible in most situations.
    I use Snake River Prototyping Blurfix Air filters on my GoPro 3 Black.They weigh less than 7 grams so don't have an adverse affect on the gimbal.I mostly use an ND4 and have an ND8 for very bright days.
     
  7. ianwood

    ianwood Taco Wrangler
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    If you shoot 2.7K medium you get no props and you can down-rez to 1080p or crop as needed. It produces much better results than shooting 1080p. You're computer will be processing more as result though.
     
  8. Hughie

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    Thanks chaps. I will try both resolutions.
     
  9. Hughie

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    I have an unbranded 37 mm filter set for the gopro but have not used it yet. It weight about 2.5g more than yours but completely unbalances the h33d gimbal. When your lens adapter and filter are fitted are you saying that with the power off to the gimbal the camera can be positioned so that it stays level in the roll axis ?
     
  10. PTCX

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    If a filter does present a balance issue you can add a counter weight to restore the balance.Use an accurate scale to weigh the filter and make the counter weight the same weight to a little heavier,a gram or so.
    This video is a good example of how to do it using the same filter as I use and the gimbal you use.
    https://www.youtube.com/watch?v=mkqDNV1ALRM
     
  11. Hughie

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    Thanks for posting. Nice video.
     
  12. PTCX

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    Thanks,but not my video.I spotted it only yesterday while looking at the SRP website,or maybe it was their youtube channel.
     
  13. f1nutter

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  14. Hughie

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    Yes that would be a good plan - at present I have the standard landing gear - but good idea.

    Another one is to tilt down slightly (or limit the "up" end movement in calibration), but I find that a bit restrictive.
     
  15. Hughie

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    I ran a few full speed tests today in the cold Yorkshire wind late in the afternoon at these settings, on a Hero 3+ Black :
    2.7K 17:9 (2704x1440) Medium FOV
    1080p *1920x1080) Medium FOV

    In GPS mode there is a relatively small amount of prop spin visible, but it could be possible that an ND filter could resolve this. I have not tried yet. I have a cheap unbranded ND4 and ND8 for the gopro, but I dont know yet how much the quality and result would vary when compared with something like the SRP ND filters.

    in ATTI mode however, for both camera settings. I can see the arms easily in both modes, and in 1080p mode I could see all 4 motor screws of the left arm as well !.

    In order to crop out the ATTI props and arms one would have to lose 25-30% (*2, top and bottom). At those resolutions above, that does not leave a lot of definition left. 4K is not an option really on this camera. I think it is limited to 12.5 fps (PAL).

    One mistake I made was to run in 2.7K 17:9 mode instead of 16:9 mode - that would have increased the height very slightly to 1524, but I dont think it would have made that much difference.