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Author Topic: Trying to understand filtering and pointcloud/mesh/DSM detail in 1.0  (Read 2588 times)

andyroo

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I am confused. I just processed a flight with better flying conditions and a second camera attached, but ended up with a worse product than my previous flight. It looks like it's because I selected "moderate" filtering instead of "aggressive" at the point cloud stage, but I am not sure.

I used the same settings except for moderate vs aggressive -because I was trying to avoid large holes in the water surface with big "flares" at their margin. It appears that I ended up with a more strongly smoothed surface with the moderate filter than the aggressive. Below I attach an image showing the results of the two model runs. The top of the image is hillshaded topography (0.5 m cell size). The bottom of the image is the two orthophotos from the two flights (a month apart - Dec 19 and Jan 15).

As an aside, with the large point cloud from my most recent flight (~2 billion points for all chunks) it takes about an hour to save the file anymore. optimizations in the save speed would be much appreciated :)


Marcel

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Re: Trying to understand filtering and pointcloud/mesh/DSM detail in 1.0
« Reply #1 on: January 24, 2014, 01:42:17 PM »
It looks like your triangles are much bigger in the latest version, are you sure you used the same settings for meshing?

Also, the more even lighting and the snow in the photos from earlier version is giving Photoscan a lot of useful details to extract depth from. I can imagine this also influences the quality of the reconstruction.

In the later version, you can see that the noisy areas line up with the parts that are in the shade. We are doing scans on a smaller scale, but we've seen similar problems with shaded areas, where Photoscan tries to extract depth from the ISO noise in shaded areas.