Php and Xmp Format: Create a Panorama 360/vr Viewer in Php and A-Frame

PHP and XMP format: Create a Panorama 360/VR viewer in PHP and A-Frame
by Janeth Kent Date: 31-10-2017 php xmp virtual reality vr 360 pano

The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for digital documents and data sets.

XMP standardizes a data model, a serialization format and core properties for the definition and processing of extensible metadata. It also provides guidelines for embedding XMP information into popular image, video and document file formats, such as JPEG and PDF, without breaking their readability by applications that do not support XMP. Therefore, the non-XMP metadata have to be reconciled with the XMP properties. Although metadata can alternatively be stored in a sidecar file, embedding metadata avoids problems that occur when metadata is stored separately.

When you make a 360 photo or panorama, you can processes the photo and presents it in an interactive viewer like the A-frame viewer. To recognize such photos upon upload, the script looks for camera-specific metadata found in photos taken using 360-ready cameras. This information is embedded in photo's XMP (Extensible Metadata Platform) and/or Exif (Exchangeable image file format) tags, and if you're sharing 360 photos or panos straight from cameras or smartphones, the script automatically does the right thing, identify the picture and show it with the right viewer. Panoramas taken with smartphones that have native panorama-capture support will be presented in an interactive viewer.

XMP data is literally embedded into the image file so can extract it with PHP's string-functions from the image file itself.

The following demonstrates this procedure using SimpleXML but every other XML API or even simple and clever string parsing may give you equal results:

$content = file_get_contents($image);
$xmp_data_start = strpos($content, '<x:xmpmeta');
$xmp_data_end   = strpos($content, '</x:xmpmeta>');
$xmp_length     = $xmp_data_end - $xmp_data_start;
$xmp_data       = substr($content, $xmp_data_start, $xmp_length + 12);
$xmp            = simplexml_load_string($xmp_data);

You can identify the equirectangular images as 360/VR images. After you have identified the images you can show the equirectangular images in the A-Frame Viewer. 

Please, note that:
XMP makes heavy use of XML namespaces, so you'll have to keep an eye on that when parsing the XMP data with some XML tools.
considering the possible size of image files, you'll perhaps not be able to use file_get_contents() as this function loads the whole image into memory. Using fopen() to open a file stream resource and checking chunks of data for the key-sequences <x:xmpmeta and </x:xmpmeta> will significantly reduce the memory footprint.

(Thanks to wohaby and alt-17 for image permissions)

by Janeth Kent Date: 31-10-2017 php xmp virtual reality vr 360 pano hits : 6614  
Janeth Kent

Janeth Kent

Licenciada en Bellas Artes y programadora por pasión. Cuando tengo un rato retoco fotos, edito vídeos y diseño cosas. El resto del tiempo escribo en MA-NO WEB DESIGN END DEVELOPMENT.


Related Posts

HTTP Cookies: how they work and how to use them

Today we are going to write about the way to store data in a browser, why websites use cookies and how they work in detail. Continue reading to find out how…

The most popular Array Sorting Algorithms In PHP

There are many ways to sort an array in PHP, the easiest being to use the sort() function built into PHP. This sort function is quick but has it's limitations,…

MySQL 8.0 is now fully supported in PHP 7.4

MySQL and PHP is a love story that started long time ago. However the love story with MySQL 8.0 was a bit slower to start… but don’t worry it rules…

A roadmap to becoming a web developer in 2019

There are plenty of tutorials online, which won't cost you a cent. If you are sufficiently self-driven and interested, you have no difficulty training yourself. The point to learn coding…

10 PHP code snippets to work with dates

Here we have some set of Useful PHP Snippets, which are useful for PHP Developers. In this tutorial we'll show you the 10 PHP date snippets you can use on…

8 Free PHP Books to Read in Summer 2018

In this article, we've listed 8 free PHP books that can help you to learn new approaches to solving problems and keep your skill up to date.   Practical PHP Testing This book…

Best Websites to Learn Coding Online

You know and we know that it’s totally possible to learn to code for free... If you can teach yourself how to write code, you gain a competitive edge over your…

PHP: Basic Introduction to Namespaces

History of PHP Namespaces In PHP prior to 5.3 (2009), any class you define lived at the same global level as other classes. Class User, class Contact, class Db they're all together…

PHP 7.2 will be the first Programming Language to add Modern Cryptography to its Standard Library

Last week, the voting phase closed on an RFC to add libsodium to PHP 7.2. The result was unanimous (37 in favor, 0 against). When version 7.2 releases at the end…

Php: How to extend the highlight_string function

PHP has a cool function that automatically highlights PHP code called highlight_string(); Theoretically this could be used to roll your own code highlighting on a site, rather than rely on…

Install Apache, MariaDB and PHP7 on Ubuntu 16.04

Ubuntu 16.04 LTS Xenial Xerus comes with PHP7 by default so you don’t have to rely on third-party PPA to get PHP7 installed. In this tutorial, we are going to…

Cuixot - Mallorca's Ham

Project: Cuixot de Porc Negre Mallorquí graphic web development SEO PHP/MYSQL, HTML, AJAX, Javascript, CSS  frontend/backoffice Pcore CMS Link: Cuixot - Productos de la raza de cerdos negros de Mallorca