close panorama
 

Multiresolution Panoramas


Example of the harbor panorama::
Resolution: 24576 x 12288 ~ 302 Megapixel
Multiresolutions: 24576x12288, 12288x6144, 6144x3072, 4096x2048, 2048x1024
Tilesize/Tiles: 1024x1024 = 24x12, 12x6, 6x3, 4x2, 2x1 = 136 Tiles (~28 MB Jpegs)
krpano XML: hafen.xml

This panorama has a resolution of 24576x12288 pixel (about 302 megapixels). To display such a large panoramic image your computer would need about 1.2 gigabytes of available memory only for the panoramic image itself.
How was this calculated? 1 pixel needs 4 bytes - is thus 24576 * 12288 * 4 = 1,207,959,552 bytes! In addition, approximately 17 MB will be required to be downloaded. (this is the filesize of the panorama image compressed as JPEG image).

That would obviously be too much for an average computer to handle. The solution is to split the high resolution Panorama image into many small parts. These parts only load into the player as necessary (as the user zooms in).
(In this example, the image is split into smaller pieces of 1024x1024 pixels in size)

So, it is now possible to view the whole panorama without loading everything at once. However, there is still a problem - depending on the angle of view - when there are very many parts visible at once, again many split images need to be loaded, and again a lot of memory is needed for this.

This problem is solved by using multiple image resolutions of the panorama. Depending on the zoom level and angle of view, only the parts that best matching resolution are loaded. This means large amounts of data are never loaded simultaniously, and therefore less memory is needed.
If the view changes, parts that have already been loaded but are no longer needed, will remain available. Only when the memory limit (memory.maxmem) is reached, the not required image parts will be released from memory. If these parts are needed again later, they must be re-loaded.

With the included Options-Plugin (top right button) the currently used memory can be displayed:

mem imagefile - the memory used by the JPEG files
mem imagedata - the memory used by of the image tiles


To illustrate and better comparison:

The panorama in the various stages of resolution (single resolution)

2 megapixel - resolution 2048x1024
8 megapixel - resolution 4096x2048
19 megapixel - resolution 6144x3072
75 megapixel - resolution 12288x6144
302 megapixel - resolution 24576x12288

ATTENTION: For the highest resolution 24576x12288 there are already problems at bigger picture angles: By default, the memory limit is 350 MB. It can not load all parts at once!



Comparison of various resolutions using a cutting:





2 megapixel - 2048x1024 - 0.5 MB JPEG files - 8 megabytes of memory

8 megapixel - 4096x2048 - 1.4 MB JPEG files - 32 megabytes of memory

19 megapixel - 6144x3072 - 2.1 MB JPEG files - 72 megabytes of memory

75 megapixel - 12288x6144 - 6.1 MB JPEG files - 288 megabytes of memory

302 megapixel - 24576x12288 - 17.4 MB JPEG files - 1.2 gigabytes of memory