Forum : Technical Preview

Get all your questions answered about our latest Photosynth Technical Preview.


Topic: How best to do walks?

Report Abuse Report Abuse
dvdhns (Over 1 year ago)
I'm retrying Photosynth2, and still not getting the results I would like to have.  Most likely my fault and not the application.

I'm ending up with a lot of floating, psychedelic trees and rocks.  In both examples below, I took photos every 3 to 5 feet.  Where the scene changed rapidly - such as passing a tree, I took them more often.

Example 1 - http://photosynth.net/view/19c61a9c-6620-4af7-bde5-edd0892f62de this had a lot of photos drop out when I passed a tree.  Also there were a few places where it looks like moving water (cool!)

Example 2 - http://photosynth.net/view/20021292-5ad5-4b98-b440-294365486b6f all the photos were used, but lots of floating objects - even in the background.
dvdhns (Over 1 year ago)
...(Hit submit before I was finished)...

Am I not taking the photos often enough?  
Am I changing the target of the camera to quickly?
Shawbum (Over 1 year ago)
You will definitely benefit from taking photos more often.  I've done quite a few lengthy walks and usually take a shot for every step or two I take.  The only downside to this is that you cannot cover as much ground.  I often hit the 200 photo limit for walks.  I normally just create multi part walks when this happens.  Sometime in the future we should be able to join these multi part synths.

Oh, and when the scene is changing rapidly I go into overkill mode and take a whole lot of photos(when I remember to that is).  This usually results in a pretty smooth photosynth even when there are lots of close objects.
Joscelin.Trouwborst (Over 1 year ago)
@dhaines. I had a look at yours and the Photosynth Team's blog post about walks...
http://blogs.msdn.com/b/photosynth/archive/2014/03/19/capture-like-a-pro-part-6-walk-tips.aspx

The example walks in the blog post look smooth. Viewing them frame by frame gives me the impression that only small steps were taken. Your scenery and path do not seem the easiest to me for Photosynth.

I had a look at a walk I deliberately shot as such recently...
http://photosynth.net/preview/view/1cfbb09f-9c68-4da4-b897-fb664db635b3
I took 1 or 1 and a half step in between the shots, which I suspect matches with your 3 to 5 feet.

My impression is that in the examples, shot distance is less than 3 feet. Also, passing objects at close distance seems to be artefact prone. (The fence and lantern poles in my synth.)
Shawbum (Over 1 year ago)
Here's an example of one of mine with a LOT of things close to the camera.
http://photosynth.net/preview/view/fbf559e2-a82b-4865-a63f-ffa790e5551d

If you press M while viewing this to see the map you'll notice that the spacing of the photos are very close through the entire middle section.  Much closer together than 1 every step.  There are significantly less artifacts, although they're still there when something passes really close to the camera.
Joscelin.Trouwborst (Over 1 year ago)
Thanks @Shawbum for your example and mentioning the map again. I should start remembering that.
NateLawrence (Over 1 year ago)
Remember that Photosynth (both 1 and 2) operate on the 'rule of 3', meaning that for a solid reconstruction of an-object/part-of-the-scene, you'll need to see it a minimum of three times. 
(This means three times where you're not more than doubling the size of the object on screen between any two of the three shots).

It's also worth noting that because Photosynth 2 only crossfades between two images at a time in the viewer that in Walk synths (unlike in Photosynth 1 or Photosynth 2 Wall synths or Panning synths) you do not get the same benefit of the previous photo filling in the holes behind you when you turn left or right, so keep your turns gradual/gentle.
dvdhns (Over 1 year ago)
Thanks all!  Great synths you shared.  Much to aspire to!

After reading your comments and looking at your synths, I'm sure I need to space my photos much closer.  

I'm still unsure about having a lot of foreground and background imagery, but it's helpful to know to not stop and do a rotate in a middle of a walk, even if you take a lot of picture - always need to be moving forward.
Joscelin.Trouwborst (Over 1 year ago)
I think that somewhere in the Photosynth Team's notes it says that walls and walks may deviate from their straight lines up to a maximum of 45 degrees. So, slow curves are possible while moving. And, not to be forgotten either, no intersections of the path. As the 'capture like a pro part 6' points out, it should be possible to connect end to start, but I haven't tried it.
You need to be Signed In to add a comment. (Are you new? Sign Up for a free account.)