Foto Panoramica 360° - © Pietro Madaschi - www.360visio.com

Technique for 360° Photographs and Virtual Tours

The 360° TECHNIQUE

How are 360° Photographs created? If you are curious about the technical aspects read these notes. If you have any questions or need information contact us through the CONTACTS webpage.

  1. Definitions
  2. Equipment and shooting techniques
  3. Joining the images
  4. The HDR – High Dynamic Range – technique
  5. Create Virtual Tours
  6. Placement in a website
  7. Little planets and transformations in two dimensions

 

Definitions

When talking about 360° Photographs one uses different terms to indicate that they allow:

  • A spherical vision: meaning Spherical Photography
  • A virtual yet real vision: meaning Virtual Reality Photography
  • An immersion into a situation: meaning Immersive Photography
  • A trip around the environment in the photograph: meaning Virtual Tour

In fact one always refers to the same technique and the same results. Actually, we prefer the simple term 360° Photograph -or Image- and Virtual Tour to indicate a group of 360° Photographs connected to each other or relating to the same subject.

Equipment and shooting techniques

Every high quality 360° Photograph is seen on the screen by the observer as one single photograph, but is actually the sum various exposures taken separately and later joined. The photographic equipment needed can vary greatly, but the minimal kit needed to create high resolution 360° Images includes:

  • A digital camera with interchangeable lenses
  • A fisheye lens
  • A tripod with a special panoramic head
  • A remote shutter

The camera with the fisheye lens is mounted with the correct settings on top of the panoramic head, which is fastened onto the tripod. The photographic session begins by choosing the point in which you want to “center” the 360° Photograph. Then, depending on the focal length of the fisheye lens, you take 3-6 exposures rotating the panoramic head horizontally. Next, you take a picture upwards (Zenith) and a picture downwards (Nadir). These two images allow you to complete the visual sphere and the second, in particular, to make the photographer and his equipment invisible. All of the pictures must overlap partially to allow them to be joined afterwards.

Joining the images

Once you have obtained images which cover the entire visible sphere with a partial overlapping between them, they must be joined, “stitched”, to create a 360° Image: this is the first step in post-production. With this goal in mind, there are various stitching programs on the market which use sophisticated mathematical algorithms to analyze the various photographs and stitch them together into a virtual spherical surface that reproduces what the photographer has seen.

This process is done automatically, but manual intervention is frequently needed to control and guide the operations of stitching, optimizing, leveling, etc. In order to obtain a high quality 360° Image, before proceeding it may be necessary to make improvements and/or corrections: for this it is sometimes necessary to use classic photo editing software.
To see some 360° Photographs in our Portfolio click on 360° PHOTOGRAPHS

The HDR – High Dynamic Range – technique

Images in 360° often have situations with unfavorable lighting. For example, on a sunny day a 360° Photograph will have great variations in brightness between the lighted areas and those in shadow. Similarly during a daytime shoot, taken in an indoor setting with windows, there will be a large difference in brightness between the inside and outside areas. The human eye is able to accept a wide range of variation in light and can compensate for the great differences in brightness better than a camera.

In 360° Images these situations are practically inevitable and can rarely be corrected during the shooting process. This is why the technique called HDR, High Dynamic Range, is used. This technique involves taking a sequence of photographs with different exposure levels (bracketing). You will be able too see the illuminated areas better in the darker pictures, which would otherwise be “burned”, while in the lighter images you would be able to see the areas in shadow which would otherwise be indistinct. The images acquired are then fused thanks to a program that generates a photograph which contains a better balance between the areas in light and those in shadow.

Create Virtual Tours

Virtual Tours are made up of a group of 360° Photographs which are logically and visually connected to each other during the elaboration process. Useful in presenting separate spaces and details, Vitrual Tours give the observer the freedom to move from one viewpoint to another: seeing the different rooms in an apartment, take a tour through the different areas of a resort, moving through the attractions and monuments of a tourist location, seeing the different holes on a golf course, etc.

Several solutions can be used to for moving around, a few of which are:

  • Visualizing the point of passing, called Hot Spot, in each 360° image
  • Inserting miniatures (thumbs) that represent each 360° Image
  • Showing a plan or map where the various points of view are indicated and can be clicked on to change positions

To see some simple examples of 360° Virtual Tours from our Portfolio click on 360° VIRTUAL TOURS

Placement in a website

The perfect place for 360° Images is in a website. But how can they be embedded and visualized within a website? The mechanism is rather complex as many technologies are used, not only photographic but also computer technology. Luckily you don’t need to know the details!

To simplify: 360° Photographs are generated by a stitching program and improved as needed, they are then converted, using a specific software, into files with a particular format and are then inserted into the program that makes the website. When the browsers enter the website they “interpret” the downloaded file and can visualize the 360° Images.

The procedure for integrating such files is not a particularly complex operation and can be performed by someone who creates websites, if needed, with our help. There is only one precaution. In the past formats like QuickTime and Flash were used, which are unfortunately today incompatible with new tablets and smartphones. The 360° Photographs that we make follow the HTML5 standard and are also compatible with the Flash standard. The files that we generate recognize automatically the kind of device that the images must be seen on and adapt accordingly.

Little Planets and transformations in two dimensions

In the past the Earth was represented on globes or reproduced in two dimensions on geographical maps. When maps show a small surface area there aren’t any particular problems, while evident distortions appear when, as in an Atlas, a map shows a continent or the entire planet: the poles become gigantic or the maps are partially sliced in crescents, etc. These distortions come from trying to represent a spherical 3D surface on a two dimensional plane.

A similar situation occurs with a 360° Image. They can be seen through a display: in this case we “travel” through the inside of a visual sphere. Or they can be projected in two dimensions and as with geographical maps, they then become distorted.

In 360° Photography the most frequent projections, or transformations, in two dimensions are:

  • Equirectangular projection: it is the projection that you can see in the miniatures (thumbs) in this website. They show the entire 360° Image “spread” over a rectangle. Since the Zenith and the Nadir (the poles) are very distorted they are usually not included completely in the miniature.
  • Stereographic projection: this is the projection that generates the Little Planets which are presented in this website and is also called polar. The considerable distortions caused by this projection can generate very pleasing images.

To see some examples of Little Planet images in our Portfolio click on LITTLE PLANETS