Black triangle on ceiling?

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larryfield
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Black triangle on ceiling?

Post by larryfield » Fri Oct 18, 2013 10:51 pm

I'm shooting panos with a 5DIII and Sigma 8mm, 3 shots @ 120° and I'm getting a small black triangle on the ceiling at the zenith. I've tried tilting up between 4-7° but then the stitching is all wrong in PTGui.

I can easily clone this out in PS but was wondering if it's something with my alignment of my camera lens?

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360Texas
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Re: Black triangle on ceiling?

Post by 360Texas » Fri Oct 18, 2013 11:23 pm

We take panoramas with a Canon 5d1 and sigma 8 mm fisheye on a Nodal Ninja R1 bracket. We tilt up 7.5° and shoot 4 at 90° and all 4 images converge properly at the top... no hole in zenith.

If this comment below is not your issue maybe its a setting in PTGui I can help you with. Talk with me on Skype (see signature block below). We are online Central Texas Time GMT -6)

Depending on how large the hole is at the top.. maybe it might be caused by 2 issues. Not tilted up far enough ( i.e. 7.5°) or maybe you have forgotten to remove the lens cap AND ring. The 8mm lens cap has 2 parts the cap and lens housing friction fit ring. Removing the end cap only will reduce your view to 120 degrees.. causing the zenith hole.

I did that same thing for about a week...LOLLLL then someone politely showed me a better technique with both cap parts removed.
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edgar_ali
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Re: Black triangle on ceiling?

Post by edgar_ali » Thu Jan 23, 2020 11:21 pm

I am having a similar issue (please see the photos) Having said this, I used the same exact photos in Panotour (Kolor) and did not have this issue before..

I am not doing something right here?:

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Re: Black triangle on ceiling?

Post by 360Texas » Fri Jan 24, 2020 5:56 pm

THE FIX:
The black dot is caused when all your final stitched image is not 2:1 ratio dimensions. example 1200 wide x 600 high or 2400 x 1200 etc.

IF your image is 2 wide :1 high and STILL have a black dot... then open it in your image editor (ours is Photoshop CS6 non CC) then zoom in and look for a thin black line at the very top of the image. The thin 1 or 2 pixels thick... is your black dot in the panorama. You can fill that black line with sky or adjacent pixel content.

THE Real FIX
The black dot is probably caused by not tilting your lens (TILT UP) far enough that when stitched all your images do not converge at the top.
We use a full circle Sigma 8mm lens on a Canon 5D1 full 35 mm sensor AND tilt the camera UP 5°. This covers the zenith hole.

When tilting up 5° the zenith hole is closed but makes the bottom nadir hole larger in diameter. The Nadir hole is either clone filled in OR we place a Nadir tripod cap image to cover the tripod and head area... This patch is useful for placing advertising information like "Powered by" our website URL or clients contact information. When the visitor tilts down they can momentarily read the useful information like Buy More Panoramas at: your company name. Its like a company business card.
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Re: Black triangle on ceiling?

Post by edgar_ali » Mon Jan 27, 2020 11:39 pm

360 Texas:

Thanks for your reply but I'm not quite sure if I understood right when you say that the hole may be caused by "not tilting your lens far enough".

When I take the panoramic photos, I use a 16 mm fish eye Nikon mounted on a nikon D3s (so everything is full format, FX). I take 6 shots horizontally and then tilt the camera 90 degrees looking at the sky. So how come I am not tilting the lens enough?

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Re: Black triangle on ceiling?

Post by 360Texas » Tue Jan 28, 2020 4:49 pm

It appears you have the right gear and take the proper number of images for your lens type.

Q. Is this a one - time issue .... do your other stitched panoramas have the same issue?

Did you try opening your stitched equirectangle image in your photo editor.... zoom in to pixel level at the top edge of your image ?
You should find a 1 or 2 pixel thick black line from top left to right image edge.

You mentioned that you take 1 zenith (UP) image. That should have covered that hole. Did you stitch your 6 @ 60° images including the zenith image?

IF you see a triangle (title of this thread) then each side of the black triangle is the top edge of each of your images. Your screen grabs look more like a well formed circle. Which might mean the 2 or 3 full width lines across the stitched panorama images.

NB
We use a Nodal Ninja R1 pan head. Sigma full circle 180° 8 mm fisheye lens. We take 4 images @ 90° around the horizon. Since the NNR1 is set for 7.5° tilt up we do not need a zenith 1 UP image. Picture pointer reads 5 degrees tilt for other panheads. All 4 images converge (closing the hole) at the top properly. On the tripod head... its difficult to actually determine the degree tilt unless the panhead allows for measurement. I can not visually determine 1 degree.

There is a Phone App that can be useful. Its called "Ridgid Digital Level" But then your tripod / panhead and camera must be LEVEL first... then tilt can be applied.
rigidlevel.jpg
Rigid Level App
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NNR1.jpg
Nodal Ninja
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Re: Black triangle on ceiling?

Post by edgar_ali » Thu Jan 30, 2020 2:57 am

360Texas:

Thanks a lot for taking the time to reply to this post. Regarding your questions:
1. So far i have opened just a couple of tours and realised this issue... I wrote before that this did not happen with Kolor Panotour, but I am just realising that Kolor Panotour automatically would restrict the images when there an empty spaces, like the hole I have, while with Pano2vr you need to that manually.

I also have noticed that when I stitch 8 images (6 horizontal, 1 zenith and one nadir) apparently this does not happen. So far I have seen this behaviour when I only stitch the 6 horizontal images and the 1 zenith... I still need to confirm this...

You mentioned:
Did you try opening your stitched equirectangle image in your photo editor.
Do you mean opening the image that looks like a cube instead of a rectangle (could not find visual example,but do you understand what I am saying?)... I have never done that before..what editor can use for that..I currently use Autopano Giga...

So far this is not a major pain since i am restricting now with the viewing limits...but eventually I would like to find out why this is happening.

Thanks again!

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Re: Black triangle on ceiling?

Post by 360Texas » Thu Jan 30, 2020 4:53 pm

Here is a 10 meter pole panorama example.

The black line across the zenith top is thicker for discussion... typically its only 1 or 2 pixels thick... but you would use photoshop to zoom in to see and clone fix it. If the black line is not removed it will display as a small round circle in the zenith.

I used a CD disk on the pole top under the camera. It covers the tripod/pole cap in the nadir.
pole1.jpg
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Re: Black triangle on ceiling?

Post by edgar_ali » Fri Jan 31, 2020 4:56 am

Thanks for the tips...I'm starting to look at those tiny hole in the panoramas :D

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