Zooming in on scalable zooming tools

Microsoft has come out with Deep Zoom, a method that uses the Silverlight 2 plugin for navigating around large online images. Deep Zoom uses the same technique as that used in online maps and virtual globes — showing a hierarchy of ever-more detailed imagery tiles as you zoom in. Hard Rock CafĂ© has an early example of the technology in action.

And to prove the point about the similarity with maps, Deep Earth uses Microsoft’s own map tiles to create a Deep Zoom version of Virtual Earth. What’s the difference between the two? Virtual Earth doesn’t really zoom smoothly but does wrap around, Deep Zoom zooms but doesn’t wrap around (at least not in the examples given).

The London-based Center for Advanced Spatial Analysis (CASA) has had a similar tool for a while, except that this is a Java application that uses the Google Maps API: The Google Maps Image Cutter. It’s main advantage over Deep Zoom is that this application lets you make your own instances of zoomable gigapixel images. (I haven’t yet seen a tool that lets you create and publish your own Silverlight-powered gigapixel imagery.) [Update: There is a tool for creating Deep Zoom images, see comments.] The main disadvantage is that it doesn’t zoom smoothly — instead, you have to step between discrete zoom levels. And once you’ve zoomed smoothly, there isn’t really any going back.

It makes a lot of sense to publish gigapixel images to the web with a technology that only downloads the bits you’re actually zooming in on. (Zoomify is another example.) But what about 360-degree panorama images? These wrap around, just like an imagery dataset for a virtual globe. Here too, CASA has come to the rescue, with PhotoOverlay Creator, which produces KML that lets you explore a 360-degree panorama in Google Earth. This java app also uses a pyramidal hierarchy of tiles.

There are several ways of publishing panorama images on the web using Flash, such as Flash Panorama Player and Lucid. But such tools have lacked support for the piecemeal loading of high-resolution panoramas. One solution has been to become a member of and upload your panoramas to a site like Gigapan which uses server-side processing to deliver up the imagery piecemeal. But for DIY types, there is now also a relatively new Flash-based panorama publisher on the market that does provide multi-resolution tiling: KRPano. Expect to see a lot more development in this space.

So now we have scalable online viewers for both Euclidian and elliptic large imagery datasets. But where is the viewer for hyperbolic imagery? :-)

6 thoughts on “Zooming in on scalable zooming tools”

  1. Deep Zoom Composer is the tool for creating your own imagery and preparing it for Silverlight. It’s Windows only, but the new version of Deep Zoom now uses an XML file format (as Silverlight itself always has), so neither Composer nor Windows are actually required in order to hack something up.

  2. Making gigapixel images panoramic and/or flat should be doable for most of these approaches. The rendering part is easy (just render on a cylinder or sphere vs. a plane). But what’s trickier is making sure you can keep up to two areas of the image in high-res focus at the same time. When you’re viewing near the edge/seam/wrap, that’s the worst case — extreme east and west seen at the same time. Otherwise, it’s just an issue of rendering the texture in some interesting shape.

    In fact, the hardest part about doing anything with gigapixel images these days is finding an approach that won’t get you sued for patent infringement. It’s a minefield.

    BTW, GE’s [patented] Universal Texture approach was internally just a big flat 2D image wrapped onto the earth. There’s no reason I can think of for them to to not repurpose that same code into a flat gigapixel image viewer too, since there seems to be a good use for it. It could live in the same app and/or plugin without too many changes, and the Clip Map approach is still much better than these other workarounds in terms of performance.

    BTW, the thing that kills me about all of these demos, cool as they are, is that no one seems to get how to have the mouse simply grab and track the image, vs. this floaty/slidey crap.

  3. I guess because you were talking about web based applications you didn’t mention Google Earth’s PhotoViewer. Especially since GE 4.3 fixed some of the bugs, the PhotoViewer is a nice way to view Gigapixel images whether they are projected in 2D, cylindrical, or spherical mode.

    See for example the “Gigapxl” or “Gigapan” layers under the Gallery layer in Google Earth. The “Street View” layer also uses the Photo Viewer, but Google only loads a single resolution for those images.

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