Multiresolution allows you to view large size images quickly and thoroughly, without full loading before start of viewing them. Multiresolution can be used for displaying both flat and spherical panoramas.
Everyone has probably already seen how online maps or satellite images of the Earth are loaded, when viewing them ‒ the needed piece of the image is loaded only when you change the scale or perspective. The way it works is the same for multiresolution panoramas too.
In panoramas made with multiresolution technology, the original picture is broken down into several layers with different dimensions. At that, each of these layers in its turn, is divided into a mosaic of many small fragments. At the start of panorama viewing one layer is loaded. Then if user wants to view more detailed image when using a larger scale, another more detailed layer is loaded, then the next and so on. When rotating the panorama towards, some of its fragments are loaded as they are being viewed in the same way.
Cube face divided into multiresolution mosaic
Multiresolution is used not only for high-resolution panoramas showcasing. Separating panoramas into the layers with multiple sizes as well solves the problem that can appear when viewing panoramas with fixed sizes on screens with different sizes. Large panorama which is displayed in a small viewing window may be damaged by alliasing (i.e. flickering, rippling on the picture when it's being moved). Besides, the panorama may not be opened on low-memory devices (for example, on smartphone). And vice versa, small-sized panorama which is displayed on the big screen, will be blurred. Therefore, we have to find a compromise ‒ to do medium-sized panorama or to create several panoramas with multiple resolutions for different display sizes.
Using of multiresolution helps you to forget about the problems connected with the screen size, as the most suitable panorama resolution is detected automatically ‒ depending on screen resolution, the layer with the optimal resolution of panorama mosaic is loaded. Therefore, multiresolution panoramas are always sharp, whether or not they are viewed on smartphone, tablet or large-screen desktop.
The example of multiresolution of high-res panorama can be viewed here. The size of spherical panorama in equirectangular projection is 43500x21750 pixels (~ 950 megapixels). Panorama has six resolution levels with the sizes of cube sides: 13312, 8192, 4096, 2048, 1024 and 512 pixels.