A few years ago Google developed a new feature for spherical panoramas to be able to be viewed on web based applications. The features of an equirectangular style panoramic image was added a new field such as metadata and this way it was possible to view this image in a spherical environment. This data especially regarding about the size and style information of the image is read by the applications to be viewed properly. Nowadays Facebook also uses the same method for panoramic images. Facebook decides whether an image is spherical panorama or a partial panorama by reading this data.
If we consider this case basically, a whole spherical panorama covers a space for 360 degrees from right to left and 180 degrees from top to bottom. Because of this reason these type of images have 2:1 aspect ratio. In other words their width is twice their height.
If you have a semi spherical image that is to say 180 degrees from right to left and 180 degrees from top to bottom, its aspect ratio will be 1:1 and with this help you have a full square image on your equirectangular image. In this case an image with a properly added metadata field will be processed in a different way by web based applications. For example when you are going around in the panorama it won’t allow you to go further when you reach an edge, it will be prevented to stich with the other edge with the help of the same logic an image with narrower angle panorama will be processed accordingly to be viewed properly.
Facebook will process an image without a panoramic metadata in a regular way with a normal image and it will be uploaded in a straight way. Thus before uploading a spherical image to Facebook you first have to edit the metadata of the image. Special cameras that are designed just to shoot spherical images and applications to shoot spherical images include metadata automatically so you will not have to make additional steps. But if you have created the panorama by yourself or if the metadata is erased in a way, you will have to add this data.
A little hint: If the image you would like to upload on Facebook is a spherical panorama most of the time it is enough to fill the data for camera maker and camera model. Enter file’s properties first then go into details tab, try writing RICOH for camera maker and THETA S for the camera model data field.
The basic problem about this is that these kind of data can’t be edited easily by users. I will try to tell you how to solve this problem with a little extension package to show this data in Photoshop and how to edit this data. Besides it is also possible to edit this using metadata editing programs like ExifToolGUI but you still have to use an extension for panoramic metadata. I will tell you the way how to make editing metadatas using Photoshop in the rest of the article but if you don’t have Photoshop and you want to use another program you can download ExifToolGUI from here and ExifTool from here and GPanel extension from here. You can get detailed information for ExifToolGUI from here.
Extract ExifTool and change the file name to exiftool.exe and put it in C:\Windows directory. Extract ExifToolGUI program to somewhere you can reach easily. Extract Gpano into ExifToolGUI folder. Run ExifToolGUI.exe and click Menu>Program>Workspace definition file>Load… and install GPano.ini file. You can see GPano metadata fields under workspace tab.
Adding Photosphere Metdata Panel for Photoshop:
By using metadata schemes created by XMP lots of features can viewed and edited on Adobe. In addition to this Adobe allows users to edit metadatas using custom schemes. By this means we will add Google’s GPano labels to Adobe’s file information panel. Don’t worry at all it is easier to be done than telling about it.
For Adobe Photoshop CC 2014 and later versions:
Download the panel extension package i prepared for you from the link below.
Extract Photosphere folder and put it in the directory below:
For Mac Os:
[Username]/Library/Application Support/Adobe/XMP/Metadata Extensions
It’s good to go! If you have made this correctly Photosphere tab will be added to Photoshop’s file information screen.
This information that was developed by Google helps position an images sizes on a spherical panorama. Now let’s take a look at the importand datafields here:
- Pano Projection: There is one single option here, equirectangular. This data is used to detect panoramic images.
- Use Panorama Viewer: This one shows if the image needs to be shown panoramically.
- Full Pano Width: Width of the full panoramic imagethat is supposed to be. Width of the image on full spherical panoramas.
- Full Pano Height: Height of the full panorama that is supposed to be. Height of the image on full panoramas.
- Cropped Area Image Width: Image Width. It is same with Full Pano Width on full spherical panoramas.
- Cropped Area Image Height: Image Height. It is same with Full Pano Height on spherical images.
- Cropped Pixels Left: Left blank side size for non full spherical panoramic images. It is zero on full spherical panoramas.
- Cropped Pixels Top: Upper blank side size for non full spherical panoramic images. It is zero on full spherical panoramas.
The Scheme below might help you understand the meanings of the fields above.
Now I will try to tell you what these values are with two examples:
⇒ If you have a full spherical panoramic image this images width will be twice the size of its height. For example if width is 6000 pixels then height is 3000 (2:1 aspect ratio) In this case this images metadata is like below.
- Pano Projection: Equirectangular
- Use Panorama Viewer: √
- Full Pano Width: 6000
- Full Pano Height: 3000
- Cropped Area Image Width: 6000
- Cropped Area Image Height: 3000
- Cropped Pixels Left: 0
- Cropped Pixels Top: 0
⇒ If you have a non full spherical panoramic image you will have to make some calculations. Especially the images that are shot by mobile phones are in this class. Suppose you have a 180 degrees panoramic image from right to left that is not 360 degrees, a narrower field is displayed such as 45 degrees. In other words it has 4:1 aspect ratio. Its size is 5000 pixels to 1250 pixels. If we put this image in a spherical environment, we will have to calculate the size of the sphere that it’s going to be in. If we want our panorama to be viewed properly for example in Facebook its metadata must like below.
- Pano Projection: Equirectangular
- Use Panorama Viewer: √
- Full Pano Width: 10000 (If the width of the image is 5000 pixels for 180 degrees image then 360 degrees environment must be 10000 pixels)
- Full Pano Height: 5000 (If a 360 degrees equirectangular image’s width is 10000 pixels then its height becomes 5000 pixels)
- Cropped Area Image Width: 5000 (Image’s width)
- Cropped Area Image Height: 1250 (Image’s height)
- Cropped Pixels Left: 2500 (The space on left when we center the image: 10000 – 50000 / 2)
- Cropped Pixels Top: 1875 (The space on top when we center the image: 5000 – 1250 / 2)
Our panorama will be ready to share when you save the file.