How to create a spherical panorama

I think many people have looked at panoramic photos of streets in Google Maps or Yandex.Maps more than once. An interesting technology that allows you, in a sense, to be virtually present in the place you need.

In addition to street panoramas on Google maps, you can place panoramas of almost any place, even your own apartment (I have met such). They are displayed as separate circles on the map.

Anyone can do this. Personally, I have already accumulated about 1.3 million views of my panoramas.

Ways to create panoramas
So, if you want to create a spherical panorama, you have 2 ways:

1) buying a specialized panoramic camera, such as the Ricoh Theta V, which I reviewed a couple of years ago

2) creating a spherical panorama by “stitching” individual images in special programs (such as PTGui).

The first method is good for its simplicity. I took out the camera -> pressed the button -> done. However, this method has a couple of significant disadvantages.

The first drawback is that these cameras are obscenely expensive. Below is a list of cameras sold in CSN at the time of this writing.

The second disadvantage is that the image quality leaves much to be desired, despite the seemingly high resolution of the images. Yes, they look acceptable on a smartphone screen, but if you look at the panorama on a regular monitor, the pixels start to ripple in your eyes. In addition, the quality of the optics and sensors in such cameras is very mediocre, so chromatic aberrations and high noise in low light are guaranteed to you.

The advantages of the second method are the relative budget (you can use the existing photographic equipment) and the good quality of the resulting panoramas.

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The cons are also obvious. Firstly, the shooting will take much longer. In this case, the use of a tripod is almost mandatory (in contrast to panoramic cameras). Secondly, you will also have to spend some time on “stitching” the panorama.

Theoretical basis
So, if, when shooting with a panoramic camera, the main attention should be paid to the settings and shooting modes (described in sufficient detail in the review ), then when shooting a series of frames with an ordinary camera, it will be necessary to take into account some technical aspects.

Lens selection

Lenses have such a parameter as focal length . The shorter the focal length, the wider the angle of view of the lens and the fewer frames are needed to shoot a panorama.

Thus, short-throw (wide-angle) lenses are preferable for creating panoramas.

Separately, it is worth mentioning such a variety of wide-angle lens as ” fisheye ” (aka “fisheye”). Due to significant image distortion, such lenses can have an angle of view of 180 ° or even more, which makes them a very convenient tool for shooting panoramas.

Tripod selection

As I wrote above, it is almost impossible to make a panorama without a tripod. But not every tripod is suitable for this purpose. With a conventional tripod, the camera rotates around an axis passing through the center of the mounting hole located on the body. In this case, a change in the relative position of closely spaced objects and their proportions is inevitable when the lens is rotated (the so-called parallax ). An example of such a distortion is shown in the following animation.

Changing the aspect ratio of an object in adjacent frames

In order to avoid this, it is necessary to rotate the camera around an axis passing through the center of the lens. Sometimes this place is called the nodal point, but this is not entirely correct.

It would seem that a slight distortion of some objects can be easily corrected by manually placing key points or hiding mismatched parts of the frame. In reality, distortions affect all parts of the frame and programs for “stitching” panoramas can be very difficult to determine the correct position of the images relative to each other. As a result, individual frames are rotated at unpredictable angles, gaps appear in straight lines that are striking, etc.

Artifacts when creating panoramas

Even if it is possible to collect a normal panorama through long manipulations, distortions in the near field remain noticeable, and it takes an unreasonable amount of time, which can discourage the desire to do this in the future.

To shoot panoramas, special panoramic tripod heads are required, which allow you to change the position of the camera relative to the rotation axes, achieving minimal distortion. They also allow you to rotate the camera 90 ° to increase the vertical shooting angle.

Unfortunately, these heads are rather bulky and not very comfortable.

An example of a panoramic head

At first approximation, it seems that shooting panoramas with an ordinary camera is a tedious and tedious task that requires a lot of time and additional equipment. In general, this is true, but the process can be optimized quite well.

Equipment for shooting panoramas
The choice of lens is a key success factor. As I wrote above, the wider the angle of view of the lens, the fewer shots we will have to take. The best option in this case is fisheye. For my old Sony NEX-7, the cheapest option was the manual Meike 6.5mm f / 2.0 lens for Sony-E mount. Its viewing angle is 190 ° – just what we need.

There is no electronics in the lens, so it is quite cheap – an order from a well-known Chinese site cost 10K rubles a penny.

The picture from the lens is almost completely placed on the APS-C format matrix, only a dozen pixels are cropped from the top, but given the large viewing angle, this is not critical.

Next, we move on to mounting on a tripod. An elongated quick-release plate, ordered on the same Chinese website for 600-something rubles, will help us to move the axis of rotation forward.

With her help, I managed to move the camera back as much as possible. True, the lens turned out to be too “thick”, so for more or less free rotation of the focusing ring, we had to put several sheets of paper under the body.

However, focus changes when shooting panoramas does not happen often. It is enough to point the lens at a more or less distant point and that’s it.

Panorama shooting
The shooting itself is not very difficult. The use of a fisheye lens allows you to get by with the rotation of the lens only around the vertical axis. Theoretically, having a 190 ° angle of view of the lens, you can “stitch” a panorama of just two frames. However, given the strong compression of the image and the loss of sharpness at the edges of the frame common for most lenses, in practice this is almost impossible to do.

Therefore, I will “stitch” a panorama of four frames. ISO value, focus, aperture – these parameters will be fixed. The shutter speed will be set automatically depending on the light (this is important when shooting in sunny weather). It is desirable to maintain the angle of rotation more precisely. Having corner marks on the tripod will make the task a lot easier.

After processing the RAW files, you can start stitching individual images into a panorama.

Panorama stitching
To create a panorama, you can use different programs, including free ones. For example, there is a free program called Hugin . Unfortunately, it didn’t work out quickly.

From the paid ones, you can watch PTGui , a trial version is available on the site, so you can practice creating panoramas (though it shamelessly litters the final images with its logo). I will illustrate the creation of a panorama using this program as an example.

First, load all 4 images into the program and specify the lens parameters.

The sequence of shots matters. You can edit it on the “Source Images” tab.

After loading the images and choosing the “Circular Fisheye” lens type, the “Crop” tab will become available, where you can set the image cropping area. This also matters for a problem-free “stitching”.

If you want to remove some objects on separate frames, you can use the “Mask” tab. For example, if a person appears in one of the frames, you can delete him (of course, if the same area of ​​space is present in the adjacent image).

Next, click the “Align Images” button on the “Project Assistant” tab and go to the preview window. If everything was filmed carefully, then the automation works perfectly.

Then click “Create panorama” on the same tab and set the parameters of the financial image.

As a result, we get a good panorama that can be placed on Google maps. If necessary, the visible parts of the tripod can be easily retouched.

How much better is the resulting panorama taken with a panoramic camera and is the game worth the candle? Let’s compare.

Left – 100% crop panorama from the Ricoh Theta V camera, right – freshly created panorama. The size of the panoramas in pixels is the same.

As you can see, a specialized tool from Ricoh is seriously inferior in quality.

Now a comparison of night panoramas.

The situation is similar.

In general, if you choose between convenience and quality, then quality is somehow preferable (IMHO, of course). And the set of a manual lens and a tripod is much cheaper.