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Author Topic: Reproducing buildings in aerial mosaics  (Read 2731 times)

tenboair

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Reproducing buildings in aerial mosaics
« on: September 24, 2014, 03:50:52 AM »
Hey all,

I just started mapping city blocks. The software seems to have a really difficult time reconstructing roof edges. I've tried a number of settings with no improvement. Aside from moving higher up to take the pictures (currently have had issues all the way up to 600 feet) and maybe using a telephoto lens, I'm looking for an alternate processing method. The point cloud looks fine, and then when I make the mesh it suddenly has gaps and ripples along the roof edges.

Should I try exporting the cloud into Meshlab/Meshmixer? Or do you have specific settings/workflow you use to reproduce buildings?

nadar

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Re: Reproducing buildings in aerial mosaics
« Reply #1 on: September 24, 2014, 04:57:12 PM »
use a digital TERRAIN model rather than digital SURFACE model...

tenboair

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Re: Reproducing buildings in aerial mosaics
« Reply #2 on: September 24, 2014, 11:46:13 PM »
Hi Nadar,

Can you elaborate on this? Where would I change this/in what step is it different?

Thanks!

stihl

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Re: Reproducing buildings in aerial mosaics
« Reply #3 on: September 25, 2014, 01:49:30 PM »
Hi Tenboair,

The reason you're seeing the rippled edges on buildings is because of incomplete building geometry and noise.

What Nadar meant to say was that you can try to use the Photoscan ground filter to make a mesh of only the ground points which makes a digital terrain model.
This will cause the ortho image not to be a so called 'True ortho' because you will be able to see the sides of buildings.

I haven't found a proper way to make proper geomtry and no noise for a True Ortho in photoscan.

tenboair

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Re: Reproducing buildings in aerial mosaics
« Reply #4 on: September 25, 2014, 06:57:10 PM »
Ah, yeah. That's what I've been doing for trees, and it worked well, but the buildings seem to have a lot of ghosting when I build the mesh from ground points.