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Author Topic: Block Edge Snap issues  (Read 2825 times)

ppkong

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Block Edge Snap issues
« on: May 13, 2014, 06:02:13 AM »
I used 784 images  created a project, because the area is relatively large, so I write a Python script to output data blocks, then each chunk separately build density point clouds, build models and textures.
But the generated model in place there is always a thin gap of the side, as shown in the following picture (2.jpg),I think it's a edge snap question. can you tell me how to handle it?
« Last Edit: May 13, 2014, 06:04:41 AM by ppkong »

Mr Whippy

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Re: Block Edge Snap issues
« Reply #1 on: May 13, 2014, 05:50:20 PM »
I think you need some overlap, then you need to manage each overlap manually (or via more scripting in other 3D programs)

You'll never get perfectly meshed edges because I assume at the dense cloud edges the geometry is being linearly interpolated beyond the last points.
If the actual points between chunk boundaries don't actually linearly interpolate then each mesh will be reconstructed inaccurately.


The ideal solution would be for edges of chunks to have the mesh creation use some overlap point data (maybe a percentage threshold of the chunk size) for detecting the flow, slice the generated mesh overlap exactly along the boundaries of the chunks, and then they will likely match ok.


Given the benchmarking thread suggests you need huge power for these geometry steps, it'd make sense to make the meshing automatically 'chunk' with overlap, and then re-weld boundaries.
I understand why you need to process continuously to get an appropriate surface reconstruction, but if you use chunks with overlapped processing and cut them then there should be very little risk of different chunks calculating different surfaces over boundaries to not have them meet up (less risk with greater overlap %)


Thanks

Dave

ppkong

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Re: Block Edge Snap issues
« Reply #2 on: May 14, 2014, 04:07:57 AM »
Thank you for the reply!
When I generate a dense point, each grid was larger than the original grid 2 m (ie. 300 m +2 m). And reconstruction mesh grid was used the original grid size (300 m). I was doing.
I think as you say the photoscan doesn't consider side issues when building a mesh, so there will still be a gap.
Incidentally, what external software is more convenient to process it?
thanks!