Photogrammetric Model Made With Iphone 4s

Sheep 1

I’ve experimented before with using my Iphone to create Photogrammetric models (not through the app, just taking the photos and running it through the Windows version of 123D Catch), with interesting but not perfect results. The other day however I found myself with a nice complete in situ sheep skeleton and no camera, so I took the opportunity to test the technology once again.

I took 49 photos with a very good uniform shade, going round the skeleton at first and then concentrating on tricky parts, like the head or the ribs. I then run it through 123D Catch and found that almost all of them had been stitched. I think the lighting really did the trick, as it created a really nice contrast between the bones and the ground, The photos were taken just as the sun had set, so it was still very light, but with no glare.

sheep 5 sheep 4

The skeleton itself looks extremely good compared to some of my earlier tests. It can be viewed here in rotatable 3D: https://sketchfab.com/show/b0ef1638d4714fcdab59c040cdb46923
I particularly like the relatively sharp edges that I really couldn’t achieve with the other models, and by looking at the cloud point I found it to be quite accurate regardless of textures. In addition to that it’s coped excellently with the rib that pokes out of the ground and the pelvis, both of which I was absolutely sure it would have a problem with. Overall I’d say the model was nearly as good as some of the models I have done with a standard camera, and I think the potential is definitely there.
The only issue I have with using the Iphone camera is that it’s still an unreliable method. I tried replicating the results today as it had been cleaned better, but the new model is more blurry, again probably due to slightly less ideal lighting conditions. Therefore I would still use my camera as much as possible, and save the Iphone for those situations in which I find myself unprepared.

sheep 2

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Using 123D Catch to Record in Situ Finds

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If you have the pleasure of excavating a collection of finds rather than an individual one often one of the problems you will encounter is how to record it in situ. Some finds are delicate and may well break up once removed from the soil, while others may have been placed in a specific way and as such their location is important. Traditional methods require planning of the finds, but Photogrammetry may offer an alternative to this, by creating simple models and allowing an accurate record of the finds as well as the surroundings.

It is a non-destructive process, and has the advantage of being quick and efficient. In addition many shots can be taken at different times to show the entire excavation process.

Here are some examples from Must Farm (2006) that were originally photographed without Photogrammetry in mind:

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The links for these models can be found here:

https://sketchfab.com/show/gvQKa4WkUPOTaegyWcOUMZQlOSH

https://sketchfab.com/show/cf038e102fcb484aa71818a46be6a4ec

https://sketchfab.com/show/vun3L1S0bb1tl0uEC4ilV9Gpmhk