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Thread: Writing in the Sky

  1. #21
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    writing on clouds is like writing on a tree, the only way to make this look ok from distance is with a very large image so you do not see the imperfections so much. A fatter beam would also help but then you need also huge power lasers.

    The view from the laser will be nice but move 100 meters away and you will see a messed up image because the clouds are not a flat enough surface. Its like trying to project on a screwed up newspaper and expecting a nice image.

    Flat enough clouds are rare but sometimes do exist.

  2. #22
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    Did a test for a very large show once with a 171 where Airforce Jets flew over at low altitude laying down a blanket of smoke.. Nil wind was required and a single flyover was not sufficient.
    A static audience somewhere behind the source on an overcast night works.

  3. #23
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    all clouds are diffuse, yes there are levels of diffuseness, you get the same effect on outdoor pyrotechnics or in a large arena where the source of the smoke is a long way from the laser source. The people at the laser source will see the image as intended, the more off axis you get the more it looks just like laser beams going through fog.

    The best and only analogy I can come up with is...think of rail road tracks, when standing in the center of them, they always appear to come to a point (at some distance individually determined by individual viewers) and maybe that is why it "appears" to work when you are at the laser source. You may not be seeing the "surface" of the cloud, but you are seeing where your vision allows you to see the "surface". Maybe not the best explanation but thats all I gots. (hopefully that makes sense because that is how I understand it)

    I have projected in rain and snow and actually love the way that makes the beams sparkle.
    Pat B

    laserman532 on ebay

    Been there, done that, got the t-shirt & selling it in a garage sale.

  4. #24
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    Now go back to the first posted (the american airlines logo).

    To the best of my knowledge, that photo was taken in San Francisco, you will note that there are NO clouds in the sky. If paul actually did project that, and took that picture (which is possible) the biggest laser he EVER had at his disposal (unless he was using mine) was a Liconix water cooled argon laser rated at about 4 watts (5 watts on its best day). The photo is a trick of a very long exposure in possibly some fog in the sky. The photo is washed out. It is possible that one could do that with even very low powered lasers that only the operator could see.

    The effects and phenomena can be probably be best explained by Raleigh Scattering.
    Pat B

    laserman532 on ebay

    Been there, done that, got the t-shirt & selling it in a garage sale.

  5. #25
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    What I don't understand is that everyone keeps saying how you only see this correctly if nearly in line with the laser source.
    If that is the case, the beams should be seen to expand as perspective 'does it's thing'.
    In the iriginal shot, they look nearly parallel, which would indicate the pic was taken from off to one side and from quite a long way 'downstream' from the source.
    If you imagine where the beams converge back to the origin (the scanners), at that rate of expansion, that would appear to be under the ground, if the camera is assumed to be at ground level.
    It looks more like an image with a blur effect dragged across the screen in Photoshop.
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  6. #26
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    WADR - it appears he has walked forward of the projector and the beams are coming over his right shoulder. You can change the perspective by changing the image size. I would bet he is within 20 paces from the projector.

    and i would like to add, it looks like it is his apartment complex
    Pat B

    laserman532 on ebay

    Been there, done that, got the t-shirt & selling it in a garage sale.

  7. #27
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    I agree with Norty completely. All the above comments about perspective and the analogies hold, but the first image does not follow them. An alternative to Photoshop is that the image is small and in the foreground. This looks similar to my eyes to the flying saucer hanging by a thread. The source may not even have been fixed.

    Regarding the perspective issue in general, the more effective technique may be a high level cloud layer. If the laser is powerful and the night dark, the longer baseline relative to the absorption depth will increase the visibility angle and then again because of the longer baseline, a given visibility angle will produce a longer radius of visibility on the ground (its squared).

  8. #28
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    Deep underground or the photo is taken at the top of a hill PhotoShop is a better theory

  9. #29
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    Quote Originally Posted by Internatlaser View Post
    Deep underground or the photo is taken at the top of a hill PhotoShop is a better theory
    I was doing lasershows in san francisco when this clown was circulating this 35mm print to his (and mine) clients as an illustration of his capabilities. I personally knew the guy, he was a real trader and barterer, he told someone at american airlines that he would project their logo on the clouds in exchange for air fare to somewhere. HE DID THIS ALL THE TIME, I never bartered...I would have charged AA $5000.00 to project their logo on the clouds. Trust me...the ONLY lasers he owned at the time were an ILT 250mw air cooled argon and a 4 watt liconix and a comodore 64 with laserdream software or something like that (I was using apple iie's at the time). As a matter of fact...I bet that same night he projected 10 different things, photographed the logos then went and made a barter deal with them. It was probably very foggy that night which explains the near field brightness. The parallelism illustrated in the photo cant readily explain nor do I try to think about it much.

    WADR - planters and norty (love ya both) are making this far more complicated than it actually is. I cant explain the phenom. you are trying to imply, but you are wayyyyy over thinking it. I personally knew the guy and his capabilities.

    Photoshop did not exist in the 1980's.

    EDIT- I would like to clarify one thing - my earlier post I said that I did not know who did the original projection. When in fact, i am fairly positive that Paul R. DID in fact do the projection...but he was such a pathological liar that I doubted that it was his "work". At that time he was taking MY WORK and calling it his own...anyway...wanted to clarify.
    Last edited by Laserman532; 10-15-2012 at 12:02.
    Pat B

    laserman532 on ebay

    Been there, done that, got the t-shirt & selling it in a garage sale.

  10. #30
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    I'm not over thinking it. All of the visual elements don't add up to something my mind interprets as 'real', given what i understand about the world around me and how I perceive it.
    Either it IS possible to view cloud projections far off axis, or something is fundamentally wrong with that shot.

    Interestingly the other shot posted later also seen to exhibit an amount of the parallelism, so maybe the explanation is with the shooter of them.

    Edit: sorry, I mean Photonbeam. Interestingly, his shots also show that the image is deformed due to being viewed from the side. The first shot looks like a good deal of geometric correction has been applied, if we are to believe it is being viewed off to one side. In Photonbeams shot we do see the effects of perspective (subtly) but we also see the distortion due to viewing angle.
    Last edited by norty303; 10-15-2012 at 13:15.
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

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