We here on the Photosynth team have received a few queries on how we select synths to feature on the homepage. The following should provide some broad guidelines and advice:
Chances are that a synth of your living room will never make it to the homepage. We try and select synths that will be of interest to all our users. Landmarks, scenic vistas, still life, and the unique, weird, surprising or strange all have a better chance of making it onto the homepage.
Just like taking a single photograph, the conditions under which you take the photos comprising the synth matter. Let's say we want to feature a synth of the Eifel Tower and we find two synths that are comparable in every way except that one was taken on a gray day in very flat light, and the other in the magic hour (just after sunrise/just before sunset) with brilliant light. The one taken in the great lighting conditions will be the one to make it on the homepage.
I'm using the term synthyness here not just to describe the % you see next to the synth on its card but rather how well the synth holds together as a whole. Things to consider:
The quality of the photos that make up the synth matter as well. They should be properly exposed, color balanced and have a resolution of at least 3MP. Having at least a few well composed shots that would stand well as individual photos within the synth helps as well, especially if these shots are used as the thumbnail/starting image/highlights.
Highlights are those little thumbnails you see down the right hand side of some synths. They make a synth more navigable and allow you to guide your viewers to the most interesting points in it. Highlights with good titles and captions are especially likely to get us excited about a synth.
Have you added metadata to your synth? Again, if we're considering two similar synths for the homepage the one with the better metadata has an advantage. Having this data also greatly increases our ability to find your synth. If we're looking for a synth of the Empire State Building you may have a great one, but if it's titled as "test" or "ny" has no tags, description, or geotag we'll never find it to even consider it. Specifically make sure you've added the following:
Your synth has to be noticed for it to be considered. Sometimes we'll be searching for specific things for a themed homepage (see the metadata section above for pointers on increasing your chances here), but other times we just pick synths we think are cool. This means we have to see your synth in the first place. This most often happens when it shows up in the recently synthed list on the explore page. Another way to help a synth get noticed is to start a thread about it in the forums.
Oh, and we also accept photo gear as bribes :-)