Smearing top of 360 pano's.

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Thread: Smearing top of 360 pano's.

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  1. #16

    Hi,

    I had been doing all of that, though according to the 'smooth' article with the sigma I don't need any minus pitch. I've been optimizing manually actually and creating the pano then viewing within Panotours. I seem to have found 6.5mm as my perfect setting without any teeth, the 'circle' is still somewhat angular however so I'm working along the top rail trying to find the correct setting there to get a real circle.
    Last edited by Ben Rubinstein; 08-21-2011 at 10:08 AM.
  2. #17
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    This is how it should look like:

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    Success,
    Heinz
  3. #18
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    Ups, another set which is complete from cut to right , ok, cut to the left:

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    You have to look close to see the very small cutting teeth, specially on the last one.

    Heinz
  4. #19

    OK I think I've cracked it, here are the RAW's www.studio-beni.net/RAW.zip sorry for the lower resolution, it's only a 5D, I can't see any teeth and this is as circular as my testing can get me so far. If I should be testing to within half mm levels then let me know please. I'm still getting the smearing at the top of the frame unfortunately, the resolution near the edges of the fisheye becomes very very soft and I'm wondering if that is what is causing it. I've tried using the above NPP points but shooting -15 degrees around with a zenith shot and see if that helps.
    Last edited by Ben Rubinstein; 08-21-2011 at 11:02 AM.
  5. #20

    Hello Ben,

    Is it OK if I chime in ?

    I have experience with the 5D and Sigma 8 lens and I can confirm that the lens is not as sharp at the edges as you wish, the result is a soft nadir and zenith when you only shoot roundshots.

    A zenith and nadir shot can enhance the result but you can also can get a much better result when you sharpen the outerpart of the images a bit.
    You can do this with Photoshop, use a circular selection tool with a large feather of approx. 50 px and select a circle of approx. 3/4 of the diameter of image circle, inverse the selection and sharpen the image.

    BTW, 6 full circular images is a bit of overkill with this camera and lens combination, even with 3 images around it is possible to stitch a fine panorama and for a good overlap, a sharp image and easy stitching 4 around is really sufficient.
    When you shoot 4 around (instead of 6 around) you have to move the camera approx. 2-3 mm backwards to get the lens in the proper NPP position.

    Tip: when using only roundshots a tilt of approx. +5 degree will give you a much better coverage in zenith.

    Success,
    Wim
    Last edited by Wim.Koornneef; 08-21-2011 at 12:02 PM.
  6. #21

    Hi Wim,

    The smearing problem I'm having is even when I'm using a zenith shot so that the periphery of the fisheye circle is not being used, it's extremely fustrating.

    Here is a crop to show the problem (heavily accentuated as it's not as apparent on a white surface):


    This is 6 frames at -15 degrees plus a zenith though the problem is identical with 3 frames at +5 degrees and no zenith shot.
  7. #22

    Hello Ben,

    Is the crop a part of the equirectangular ?

    If so this is not smearing but just the way the pixels in zenith (and nadir) are normally stretched.
    You should only judge the quality of the nadir and zenith of the pano when the equirectangular is remapped to cubes or viewed as Flash or QTVR pano.

    BTW, imo your image looks a bit oversharped (perhaps this is due the accentuating you applied).

    Wim
    Last edited by Wim.Koornneef; 08-21-2011 at 12:25 PM.
  8. #23

    Not a bit, hugely! :-) I had to oversharpen and over contrast the image to show the pattern in what is just a white blank surface.

    If you look at the link at the very beginning of this thread the effect of this smearing is having at the zenith with this spiky 'bellybutton' effect.
  9. #24

    Hello Ben,

    The first link in the thread gives a 404 error...
    (http://www.studio-beni.net/Town.html)

    You didn't answer my question of the crop was taken out of a equirectangiular, this is important to know as I suspect that if this is part of the equi nothing is wrong...

    Wim
  10. #25

    It's a 360X180 if that helps and it's the top 10% of the frame. Sorry not sure what you were getting at?
  11. #26

    Hello Ben,

    So the crop is from a 360x180 --> equirectangular --> stretched pixels by nature in zenith and nadir--> always a smearing effect when viewing an equirectangular at nadir and zenith.

    You really should remap the equirectangular to a cubic pano to judge the quality of nadir and zenith.
    You can do this with PTGui by converting the equirectangular to Flash or HtmlCss3 pano or by outputting the pano as QTVR instead of equirectangular.

    I have stitched your example images and the output looks fine to me (except for a small hole in zenith and the many bad spots caused by dirt on sensor and/or lens) so I think you are a bit to critical about the quality...
    The NPP setting looks fine to me, very low CP errors and no stitching errors so you got it right.

    Wim
  12. #27

    Ben, Is this shot of the zenith showing what you call "smearing" : http://tinyurl.com/3otejzz . I think the radial streaking is the stretching of noise due to the image warping at the edge of the image circle. The sharpening you have applied has accentuated the effect. If you apply some noise reduction and don't sharpen in ACR, then the smearing will be considerably reduced. Shooting at a lower ISO setting (with longer exposures) will reduce the noise too.

    John
  13. #28

    Quote Originally Posted by John Houghton View Post
    Ben, Is this shot of the zenith showing what you call "smearing" : http://tinyurl.com/3otejzz . I think the radial streaking is the stretching of noise due to the image warping at the edge of the image circle. The sharpening you have applied has accentuated the effect. If you apply some noise reduction and don't sharpen in ACR, then the smearing will be considerably reduced. Shooting at a lower ISO setting (with longer exposures) will reduce the noise too.

    John
    I'm getting it even when the zenith shot is the only one used for that part of the zenith, i.e. it's the center of the frame rather than the edge. I'm going to do a test outdoors in a couple of hours (bit tied up now) and post up the results with what should be mm perfect NPP according to the smooth method. Then you guys can tell me what you think.
  14. #29

    Hello Ben,

    It could be very well that over sharpening in ACR is the reason of the pattern John showed in his screenshot.
    I didn't see this pattern in my output because I processed the RAWs with Canon's DPP software with a moderate sharpening (using a non canon lens with DPP is only possible after modifying the Exif info to fool DPP).
    The pattern itself is normal for many other fisheye lenses when using only roundshots but is not disturbing if the noise is removed and the image is not oversharped.

    The grey spot in the center of John's zenith image is caused by the dark edge of the circular fisheye image, with a smaller crop circle the dark spot is gone but then you have a small hole in zenith, that is the reason why I suggest to use a tilt of +5 degree to get a better coverage of zenith.

    You said that the smearing also occurred in a pano when using rounshots with a downtilt of 15 degree and a zenith shot, the radial pattern John showed is then not possible as there is no overlap of the roundshots in zenith so I am puzzled what the smearing is you are talking about.
    If you show a screenshot, or a crop, of the cubic pano then perhaps that can make clear what the smearing is.

    Wim
  15. #30

    Right,

    Here is an example of the problem I was having with the smearing showing up in regular pano's at the zenith (not on first pano but pretty much all the others) http://www.studio-beni.net/Bart.html This was using the NPP values provided by NN.

    Now here is a VT showing two pano's, one shot with zenith and one without, now using the NPP's obtained with the 'smooth' method that Heinz had recommended. The smearing is still there but not showing up with regular processing and the zenith now looks clean: http://www.studio-beni.net/New.html

    I've just gone and shot an HDR of the same scene to see whether the HDR processing is accentuating the smearing. HDR is very important to my shooting as most of the times I get into properties it's the middle of the day and I need to preserve window view details. I'll report back as soon as I've done them!
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