How to create a equirectangular image

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Tengil
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Joined: Wed Mar 12, 2008 10:19 pm

How to create a equirectangular image

Post by Tengil » Wed Mar 12, 2008 10:50 pm

Hello guys,

I try to understand how equirectangular images are being taken but I still don't get it! This is the equipment I use. Canon 300D with Tamron 28-75 lens. As you see it is not really wide angle. I do have a tripod but unfortunately not a fish eye-lens.

I read somewhere that I should take a row of pictures 30 degrees up and a row of pictures 30 degrees up. One picture facing the ground (nadir) and one picture facing zenit. How many pictures do I need to take in total?

Finally, what program do I use to stich all these pictures together so they become one equirectangular image?

:?:

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360Texas
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Re: How to create a equirectangular image

Post by 360Texas » Thu Mar 13, 2008 3:34 pm

An equirectangular image is any image that has a 2:1 ratio. Example, 2500high x 5000 wide, 2000 x 4000, 1000 x 2000... or an 1024 x 2048.

The Canon 28mm has a 65 degree vertical angle holding the camera in portrait [long side up]. Yes 30 degrees up and 30 degrees down works as long as you have say 20-30% overlap vertically and horizontally. This will give you a +/- 100 degree vertical angle of view. These are called multi row. What you won't get is an image set that is 2:1 ratio. But not to worry. Go ahead and stitch your image sets. You should get an odd dimensioned single image. In photoshop resize your image width down to an even width dimension like 9000 pixels and let the software adjust proportionately the height.

Now you have an image that is 9000 pixels wide. In photoshop create a new blank picture canvas with a black or white background color that is 9000 wide by 4500 high. Copy your stitched 9000 wide picture and paste into the new 9000 x 4500 picture canvas. Flatten it. Save it. Now you have an equirectanglar image that is 2:1 ratio dimensioned. BUT you have a white or black band across the top and bottom on the image.

Open Pano2VR and load up this new black/ white banded new image. Create a QTVR .mov or Flash .swf. When you view the image tilt down or up and you will see that you have a black/white hole in the top and bottom. This is because your lens does not have a large vertical field of view like a fisheye lens that has a 180 degree angle of view.

Hope that helps
Dave
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