Forum : Advice & Critiques

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Topic: Low res images not being matched

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mwiththeat (Over 1 year ago)
Hi,

I am trying to build a synth from a mix of old historic images and also new DSLR images of the same building.

The issue I am facing is that none of my historic images are getting mactched, is this due to the fact that they are low res? I have ensured that there are modem DSLR images which cover the area where the historic images are.

When we look at the origional notre dame synth demo, a poster were reconised by the synth client - Has the client had its power reduced to provide a better user experiance for the masses? I would love full power :)

Is there any way of forcing the synth client to be more precise or to take longer when it performs the image matching tasks? Have loads of time and processing power for this task.

Thanks

Matt
Nathanael (Over 1 year ago)
Hi, Matt, I answered your post in the Suggestions forum as well, but I'll say a bit here as well.

It's true. The synther only uses 1.5 - 2 megapixel versions of your photos to perform the image feature extraction, matching, and scene reconstruction. For references where the Photosynth team members have said this, see this old topic for three links at the top: 
( http://getsatisfaction.com/livelabs/topics/what_is_the_maximum_resolution_used_for_feature_extraction )

A simple concept for helping Photosynth recognize any particular part of a scene which I have found to be highly effective is simply to circle parts of a scene or object. This has many different benefits, but suffice it to say that the more attention that you pay to any particular surface, especially using this basic technique can yield the perfect lattice for any other images to fit into.

Please visit my "Orbital Propulsion" synth (in both viewers) for more details and a demonstration of the effects.
Nathanael (Over 1 year ago)
I'll grant you that I take the technique to extremes not necessary for a building, but several overlapping arcs of photos along a wall at close range and at least one large arc at a farther range that captures the entire wall is a good policy for getting Photosynth to robustly recognize each part of each wall. 

In buildings with more than four walls I think that I would quickly limit myself to one large long distance arc per wall. Even this would provide an excellent place for your vintage photos to nest inside of. 

If the historical images are lower resolution than 2 megapixels, it might help them to match the DSLR images to upscale the low res images to slightly over 2 megapixels and use a gentle Gaussian blur to take the visible corners off of the magnified pixels so that the image again looks smooth when viewed at 1x scale.
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