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Virtual accuracy contest (Read 12872 times)
Hondero
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Re: Virtual accuracy contest
Reply #45 - Dec 1st, 2011 at 12:39pm
 
Well, till now we have two sorts of suggestions to measure the distance. One, that could be called “direct” method (suggested by Yurek and Jaegoor), uses a tape, wheel or rope to measure. Other, that could be called “comparative” method (suggested by Ulrica and me), estimates the distance from the slinger position comparing dimensions. The first one is more accurate but needs more time of video. The second one, being shorter, may be less accurate (though enough valid).

I think the easiest way to use the direct method is with a rope or cord of enough thickness to be seen in all its length in the video. So there is no need to buy tools like long tapes or measure wheels if you have not yet one. I like to imagine the process: the slinger walk to the target holding a stick of 50 cm (the target diameter). There is a rope stretched between the target and the shooting position. He checks up the target with the stick and walk back dragging the rope to the camera position. There he measure the stick and the rope (the rope can be folded several times to measure only a fold). Then the series of shots begin. The camera position and the zoom can be free.


The comparative method requires that the zoom adjustment and the distance from the camera to shooting position are fixed for all slingers. Also the heights of the target and camera to the floor are fixed. The camera must be not touched during the video (except initially as we shall see), which is easy to check up in the image. Suppose for example a camera-slinger distance of 5 m. and a height of the camera (lens) of 1 m. There will be a pole or stick at the slinger position of 2 m height that fill permanently the entire height of the image. The top of the target will be also at 2 m. height (the center will be at 1.75 m). If the top of the target in the video matches a height of 1.20 cm on the pole, height that will have previously marked on it, then the distance will certainly be of 20 meters. To clearly understand this calculation one can make a little drawing.

To check up these fixed positions of the target and the camera, you could proceed as follows: the video begins by zooming on the target as close as possible. There will be a common object close to it, like a beer can (empty if possible,  Cheesy). The can may even be stuck on the target with plasticine, and possibly come away at first impact on the target. If its height is 12 cm then the target will measure approximately 4 cans. Likewise, the height of the base of the target on the ground should be three targets. After checking the target, zoom back to its fixed position, covering exactly the pole height, and remain there motionless for the entire video.
The height of the pole will be directly measured with a tape and the camera-pole distance also with a tape, attaching its end to the pole and extending the tape till the camera lens ( blurred fingers will occupy the entire image).
Procedure time is small as there are not  need of walking to the target and its verifications can be made stopping the video (1 second of video on the target will be enough).  Only the distance camera-pole would take 5 or 6 seconds.

If we don´t find another method we can use one of these. Which seems most appropiate?
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Morphy
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Re: Virtual accuracy contest
Reply #46 - Dec 1st, 2011 at 1:06pm
 
I would vote for the first method. The way I was planning on doing it is to have a 25 meter length of rope with a stake tied to each end. I would be standing at the 25 meter mark in the video with the camera a few feet away from me. I would pound the first stake into the ground at this pre measured 25 meter mark. Then proceed to measure the rope along the meter stick starting with the the stake in the ground while on camera. Once I had shown that the rope with the stakes was exactly 25 meters I would walk out to the target with the meter stick and the opposite end of the rope in hand. When I reached the target I could knock on it with the other stake showing the rope was taut and that it was 25 meters away and I was standing next to the target. Then pound the stake into the ground next to the target. Now I would have a 25 meter rope stretch taut between the two points. Then hold the meter stick up to the Diana showing it is exactly .5 meters across. (The meter stick would be colored so exactly half was a bright color. When held up to the Diana even at a distance it should be easy to see that it is half a meter across.

A measuring wheel would be a lot easier. I may have to invest in one if we actually start doing this regularly.

Let me know what you guys think.
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Yurek
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Re: Virtual accuracy contest
Reply #47 - Dec 1st, 2011 at 1:33pm
 
Morphy, I just meant filming either the measures and slinging in the same take. The measures can be  pretty quick. There is no need to remove the camera from the tripod. It would be enough to bring the wheel or tape to the camera close enough to see the readings. If someone use a measuring type, he would have to stretch it on the ground between the target and "slinging line", next grab the tape in the proper place with two fingers and show the scale to the camera. Similarly with the wheel - show the "zero reading", roll it to the target and show the "end reading". Thats all about the distance. About the size of the target, the slinger could use the same method like during measuring of the slinging distance with a tape or just measure that one close in front of camera and next hung it up in its place.

Morphy, I think if someone wants he could use a smaller target, no problem. But besides making others jaw drooping he wouldn't get extra points Smiley

Oops, I didn't saw Hondero's Morphy's posts above  .
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Yurek
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Re: Virtual accuracy contest
Reply #48 - Dec 1st, 2011 at 1:55pm
 
My Friends, you are going to make things too complicate. There isn't simpler method than direct measurements with using mentioned tools. There is no need to buy expensive wheels or long tapes. A 5m or even 2m tape is pretty cheap and I think most of us own a one. Of course a long one or wheel would be more easy to use, but there is no problem to measure the 20 m distance with a 5m tape and show it in front camera. I can't understand why measuring of a stick with a measure type and next measuring of a rope with the stick is better than a direct measure. The same with other indirect methods which require calculations and are both complicated and inaccurate.
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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Hondero
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Re: Virtual accuracy contest
Reply #49 - Dec 1st, 2011 at 2:20pm
 
Yurek wrote on Dec 1st, 2011 at 1:55pm:
The same with other indirect methods which require calculations and are both complicated and inaccurate.



Indirect methods could be more dificult to understand the calculus basis , but they are more simple to carry out than walking onwards and backwards between the target and the shooting line Cheesy. As simple as to see in the video how the top of the target mach a mark on a pole.
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Morphy
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Re: Virtual accuracy contest
Reply #50 - Dec 1st, 2011 at 2:54pm
 
Yea that would be easier... I guess I was thinking from the point of view of the easiest way to do it right this second rather than going out and getting a longer measuring tape LOL... ahh... I need a nap.  Shocked

As far as using smaller targets I think at some point that is just going to be the natural progression of things eventually.
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Hondero
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Re: Virtual accuracy contest
Reply #51 - Dec 3rd, 2011 at 8:37am
 
It seems that we have reached an impasse, but perhaps we have achieved the intended purpose of analyzing the possibilities of organizing a virtual contest. Beyond the natural disagreementes and preferences of each one on the method to test the standards, I think we have all shown that the virtual contest is possible. Another thing is to decide and specify  in detail the procedure, and especially to start the contest. In my case, I have still much to train before I hit at least 8 out of 10 times the diana Tongue.
When I have time I´ll make a real test of the different methods, comparing its length, reliability, video observation, etc.
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Yurek
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Re: Virtual accuracy contest
Reply #52 - Dec 4th, 2011 at 4:36pm
 
In fact doesn't matter how someone would measure/prove the slinging distance. The only one thing is important, a chosen method should be convincing for most of us here. I would use a measuring tape or wheel when I decide to film my shots. Hondero, I think that these indirect methods are clever and sometimes very useful. If someone would want to use a one - why not. However it would be more difficult to defend it when is questioned. Anyway I am curious of results of your test, it is interesting though. When we know them it would be time to work up clear simple rules.

Alas, I am afraid the present time isn't favorable for discussions about contests. People are rather prone to think how to survive an apocalypse Wink
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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