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In this article I am going to show you what is a 360×180° panoramic photography and its possibilities. I hope I can show you how fascinating it can be. It is, nowadays, one of the most complete ways of knowing some place without being there. That is one of the reasons why it is also called “Immersive Photography”. In the following sections I hope I can get your attention to the subject and maybe teach you how to make it under a BSD or any Unix like system, using only free open source software.
After reading this text you will know:
To follow the first step of this article as a simple 360×180° panoramic photography spectator you should basically know how to use a computer, and access the Internet using a browser with a flash plugin or an apple device.
To learn how to make a basic panoramic photography you should:
To learn how to make and publish a complete 360×180° panoramic photography you should also:
Electronic engineer, graduated in 1995 in UFRJ2). Have worked for around 15 years with Unix, mainly with FreeBSD but also Solaris, Tru64, Linux and others. Experienced in free and open source software, IT infra-structure, network management, system development and project management. Organized the BSDCon Brazil in 2003, created the “BSD em Revista”, the first magazine dedicated to BSD in Portuguese and the news site http://www.myfreebsd.com.br (not online anymore). Organized and taught in FreeBSD courses. Studied photography at school in 1985. Built amplifiers, tripods, home made cameras and so on. Make panoramic pictures since 2002 and got specialized in 2010. Keep a blog of immersive pictures3) and the first open forum in Portuguese, the Panoforum4).
If you like photography and have a hack spirit, as almost every BSD enthusiast, you probably have already tried to join two or three pictures together to make a panoramic image. If you haven't yet you probably can guess that this is possible, don't you? What about Google Street View, do you know it?
Well, anyone can guess what is a panoramic image. One possible definition is that it is a picture that extends the lens or the human eye field of view. The most accepted is that it is a question of the field of view degrees, but sometimes it is hard to discover the angle used in a ready made picture, so we finish with the image aspect. Probably it is ok to call any picture with an aspect of 2:1, or wider, a panoramic photo. Most of the times it is achieved by joining pictures together to make a new one with a wider coverage angle. The “immersive” or “360×180°” or “full sphere” or “spherical panorama” is the panoramic picture that extends this to the wider possible angle, covering all visible areas.
To see a full sphere picture you will need a specific software or the image will have some distorted parts. The best way to look at them is interactively, in a computer or any other device, preferentially with a big screen. These pictures are usually not very much adequated for printing, although you can convert them to some projections that are better for that, like the equirectangular or stereographic. This last is also called “little planet” in an allusion to the classic “The Little Prince”. Figure 1 shows an image in a stereographic projection.
After this little introduction it is a good idea to have an immersive experience. Follows some links where you can see some of these pictures, and these is only a very small list of them:
Try to experiment everything, clicking and dragging to every side, up and down too, making zoom in and out and so on. Most of the people get really impressed and a good amount gets astonished with this kind of photography, mainly when it is made with high quality. Google street view doesn't care about perfect quality and even this way their images cause a good impression. The possibility to have a point of view as if we were in the place and be able to chose what to look at is really amazing, isn't it?
Google Street View is available from the Google Maps5) system but they have not shot everywhere yet. Small cities and countries might not have it. With it you can discover the place without going there physically. Try to see some streets in New York, Rio de Janeiro, London or Tokio. It is totally amazing. Probably every BSD user already know how to use it, but anyway, you need to put the map over where you want, click and drag the orange little guy figure over the zoom rule on the left side and release the mouse button when the guy is over some street. The streets with street view available will turn to blue when you start dragging the orange guy. You will need flash plugin to see this.
By now you can probably guess all the possibilities of this images: hotel sites, tourism, realstate, restaurants, parks, … Any enterprise or individual that want to show any place can take advantage of this. Even those crazy guys that only what to keep a family memory. Do you think it can be made totally with free software? Surely! The free softwares available to make panoramic images already exist at many years. Hugin, the main free software I use to stitch my photos, has its first files at sourceforce dated from 2003. And he is only a GUI to other tools, like PanoTools, that already exist before that. The German physician and mathematician Dr. Helmut Dersch has began to make PanoTools in 1998. In 2004 I have made the first Hugin and its dependencies ports to FreeBSD. In 2000 I have participated in a project to build an Internet Brazilian tourism portal that used 360º images to present hotels. It was a big news at that time, but the picture qualities were much poorer than today and also the computer and Internet capacities were inferior, so it was difficult to make higher resolution images. Nowadays it is possible to make images with very high resolution and commercial quality using only free software. So let’s start talking about the process and free software tools that can be used to make such images. I have already made some speeches and workshops and I usually like to split the process into steps, like this:
Each step has its own details and secrets to achieve a good result at the end and I will try to talk a little about each. Before that, however, let me try to show you a simpler process to mount a partial panorama with just a few images.
For a beginner it is surely easier to start mounting a partial panorama. For that you just need some images taken with some overlap between them, like 30 to 50% for example. There is no need of specific cares about the way you shoot and probably also won't have no need of post editing.
Hugin site has a very good English tutorial on it6). By doing this step one can have a first contact with the tool and start recognizing it's menus and tabs. The good aspect of the tutorial is that it teaches you how to do the steps manually. It is not so important when stitching just two pictures, but can be necessary to join a full sphere panorama, so it is a good way to start learning to do a full sphere.
First of all we need to take the pictures (obviously). It is possible to use any camera to do a spherical panorama, but it is highly recommended that it has “Manual Mode” and that you use a panoramic tripod head in a tripod. It is also possible to make it not using all this, but it can put the newbie in such a difficult situation that he might give up without been able to finish his first panorama. Without the manual mode the color and luminosity difference between images will be very difficult to solve, although yet possible. One will also have a hard time to correct parallax errors without using an adequated tripod head. Nevertheless, my very first stitch had all this problems – and it never had a good final quality. It is shown in Figure 4. It has been made with a common point and shoot camera (Olympus C-120) using a common tripod and automatic mode. I have made 42 pictures to cover the full sphere. It is easy to see each original picture in the final stitched image.
For the beginners I strongly recommend making the previous step, mounting a simple panorama to get used with Hugin. Patience will certainly be of great value in your learning journey, cause mounting a complete sphere panorama can take some time. If you are going to try to shoot without a tripod, some important tips are:
Those tips will make your first try much easier. Using a tripod would make it easy? Yes, but the best would be using a tripod with an appropriated head for panoramic shooting. Rotate the camera around the No Parallax Point makes a huge difference in the stitching step and it can be made using this tripod head I mentioned.
There are many models of panoramic tripod heads and you can even make your own one at home. There is a page in the Panotools Wiki7) that shows many commercial models of them and also many home made ones in the section called “Self Made”.
But who in hell is this guy called No Parallax Point? Even if you can't buy or make your own panoramic head, it can help a lot if you know where he is. This will decrease the perspective errors, usually called parallax errors, making it easy to stitch and decreasing the need for post editing.
In a few words it is the point that, if used as the axis for rotating the camera, won't cause any perspective errors between the objects in the scene. Usually it is located in front of the camera, many times in the middle of the lens. In Figures 9 and 10 we can see some examples of panoramic tripod head being used to turn the camera using the no parallax point (NPP).
The No Parallax Point is sometimes confused8) with the Nodal Point9), which is an optical concept and not necessarily is the same point where one would be able to shoot pictures with no parallax errors10). Well, what I want to tell you here is that there is one special point where you can put the rotation axis of the camera and this way you will be able to take pictures rotating the cameras and have no parallax problems. And what is a parallax problem?
Between Figures 6 and 7 it is possible to see a parallax problem. Notice how the big difference of position between elements like the island and the window, the buildings and the window and so on. An object that was behind the other can be seen in the next picture. The relative position between objects changes as we rotate. The resulting image will have probably some problems. In Figure 8 I tried to joing the two pictures. We can see lines not joining (1), a building that got distorted (2) probably to make it possible to join another part of the image and an object showing twice (3).
If we use an appropriated tripod head and rotate the camera around the NPP the objects would be exatcly in the same relative position, making it much easier to stitch pictures then.