Photograph 360 Degree Around With A Nodal Rotator
A rotator Nodal is a must for precise capture of panoramas with consecutive shots, especially when the image includes objects nearby, such as is the case with indoor panoramas.
This does not mean that you can not simply turn a camera taking pictures and put them together into a panorama, but when the camera turns to a side nearby objects tend to move covering and discovering the different objects in the background. If the picture contains only distant objects, as is the case of a landscape panorama, this phenomenon does not occur and the overlapping portions of the photos to be joined are very similar, which makes the task of editing not only possible but even easy.
If there are nearby objects, the movement of the camera between shots will normally produce a relative movement of objects as nearby objects seem to move more than distant ones, and then the images would not be able to be stitched without defects.
Unless the camera is rotated around the nodal point of the lens.
What is the nodal point of a lens?
The nodal point of the lens is the point all light rays cross after having traversed the lens. It is located on the central axis thereof and their separation varies according to the characteristics of each camera, lens, and also its location, for example if the zoom is in its extended position, or it is contracted or in an intermediate position. In the case of wide angle lenses, such as fisheye, the nodal point is within the lens, a few millimeters behind its surface.
Considered from the point of view of an interactive panorama, the nodal point is the point around which the observer looks at the big picture. This is because the panoramas are not three dimensions, which would require two different points of view (eg, two eyes), but are flat images, viewed from a single point of view, that is, from the nodal point of the lens.
The importance of nodal point is that only if all pictures in a sequence intended to merge into the same panorama are taken keeping unchanged the nodal point of the lens, only in this case the images will perfectly match to each other and the editing of the picture will be simple and fast and the final result will be free of defects.
However, in case of changes between shots, such as camera shifts or rotation about any axis other than the nodal point's, the areas photographed in successive shots will have differences between picture and picture, differences that will become greater as the photographed objects are closer to the camera. The influence of the aforementioned small camera movements is nearly or completely undetectable in distant objects, but causes much larger changes the closer the object is to the camera, to the point they can make the creation of the panoramic image fail.
How do we find the nodal point of a lens?
Other than complicated methods involving measuring devices, laser light pointers, etc, a practical way to determine the location of camera's lens's nodal point is turning the camera from right to left and viceversa, while looking at the screen to find movement of the objects in view relative to other objects. You'll find for this it's worth it to place a narrow object, such as as a needle or a pencil in vertical position, in a place close to the camera, to use it as a reference. If when turning the camera to the sides we see that our reference object moves in front of the objects in the rear part of the scene, hiding and unhiding them from view depending on the camera's orientation, this means the axis around which we are turning the camera is not aligned with the nodal point of the lens.
Then we'll need to move the camera a bit forward or backwards and repeat the experience. If the relative movement of the objects is now smaller we are on the right path. If instead it has grown more apparent, the change in the camera position has surely put the nodal point of the lens further away from the axis around which we rotate the camera. If we repeat the step the neccesary times until we find the position in which when turning the camera to the sides the objects in view never move in front of other objects, this means that now the axis around which the camera turns matches exactly an axis that contains the nodal point of the lens. The nodal point, also, is horizontally aligned with the center of the lens.
If we only want to photograph a strip or horizontally alinged shots, it will be enough to make the vertical axis of the nodal point coincide with the vertical axis of the camera rotation. If instead we are going to photograph a higher panorama in multiples rows, then we'll need to determine the precise position -both vertical and horizontal- of the nodal point so that nearer objects will not move in front of objects in the background when we change the vertical position of the camera.
The procedure is similar. This time it will be more useful to place our pencil or needle in horizontal position and to move the camera pointing alternatively up and down. To determine with presition the nodal point of a lens requires attention and patience. To keep the camera in the exact place while moving it to photograph the panorama is almost impossible unlees we count on an element which can hold it firmly in place.
What is a nodal rotator?
A nodal rotator is an accesory for panoramic photography, which is mounted on a tripod and to which a camera can be adjusted, so that the nodal rotator guides the turning movement of the camera around its lens nodal point, thereby constraining the movements of the camera to rotate only around the nodal point. In this way, you take all the photos you want being sure that at editing time, all of them will be seamlessly stitched together.
There are different types of nodal rotators. For this tutorial we have classified them into three categories :
And we will begin by presenting the first.
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With any camera
360 Degree Interactive Panoramas
In Three Easy Steps
After reading this tutorial you'll be able to create your first 360 degree interactive photography with the camera you already have :
1 - Photograph
Take one or more pictures of the place you want to show.
2 - Edit
Convert your pictures into 360 degree panoramas.
3 - Publish
Make your panoramas interactive and available to the world on the internet.
If a picture is worth a thousand words, a 360 degree interactive panorama is worth a thousand pictures...
Online Virtual Tour Creator
Using the online virtual tour creator you can :
Convert your 360 degree pictures to virtual tours with a single click.
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Know in a practical way all kinds of 360 degree pictures.
Discover that you can create hundreds of interactive virtual tours just as easily as you take pictures with your camera.
Check that with just one click from your camera and another click from your mouse it is possible to create a 360 degree interactive virtual tour out of nothing. And completely free of charge!!!
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