Original Message:
Sent: 11-22-2024 08:14
From: Zach Edwards
Subject: Point Cloud Sampling issue
I would also suggest that you check your preferences/options and TBC to make sure that you are using the maximum amount of ram it's in the point cloud section underneath the options. If you type 100 in the ram field and tap tab, You'll see a number that is almost exactly 50% of your total ram. I would say the bare minimum is 32 gigs of ram to run TBC with point clouds (leaving roughly 16gb for TBC alone).
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Zach Edwards
Original Message:
Sent: 11-21-2024 01:23
From: Marek Lepkowski
Subject: Point Cloud Sampling issue
Hi Ramin,
I tried cloud sampling in TBC 2024.00 and also v5.0
Point cloud spatial sampling in Project Options = 100 000 000pts
Result was the same.
I made some tests to check when TBC works correctly with sampling.
Firstly, I sampled my point cloud in Trimble Realworks (old version 11.3) to get theoretical number of points. (Sampling in Realworks works without issues)
Realworks: 25 938 930pts / sampling 0.10m = 664 007pts
TBC: 25 938 830pts / sampling 0.10m = 447 903pts
Nextly I split my point cloud to 3 parts, station 1-8; 9-14; 15-20
Part 1 (Station 1-3)
Realworks: 10 513 688pts / sampling 0.10m = 266 500pts
TBC: 10 513 688pts / sampling 0.10m = 260805pts
Part 2 (Station 9-14)
Realworks: 7 216 010pts / sampling 0.10m = 204 589pts
TBC: 7 216 010pts / sampling 0.10m = 204 639pts
Part 3 (Station 15-20)
Realworks: 8 209 132pts / sampling 0.10m = 193 084pts
TBC: 8 209 132pts / sampling 0.10m = 193 053pts
We can notice it looks fine wih Part 2 and Part 3. Part 1 difference around 6000pts.
Finally I merged Part2 (station 9-14) with Part3 (station 15-20)
Realworks: 15 435 142pts / sampling 0.10m = 397 560pts
TBC: 15 435 142pts / sampling 0.10m = 333 035pts
My conclusion:
TBC works correctly only with small parts of point cloud - up to 10 000 000pts ?
I'm not happy about that, it causes extra work which i would like to avoid...
Point cloud below:
https://drive.google.com/file/d/1sk3fkoc9Ou2VGXl9q6J8hpiSvzMwGkZZ/view?usp=sharing
PS.
I noticed also if you have more than 10 000 000 points of cloud in one TBC project, sampling doesn't work correctly even if you select a smaller cloud segment...
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Marek Lepkowski
Original Message:
Sent: 11-19-2024 15:22
From: Ramin Rad
Subject: Point Cloud Sampling issue
Hi Marek,
TBC's spatial sampling is designed to thin out points for an even distribution, but that can sometimes lead to distances between points being larger than you'd like. If your point cloud is pretty big, TBC might first apply a reduction step, which is controlled by the Max number of points setting in the Project Options. This initial thinning can mess with the uniformity, especially in areas where the point density varies.
The algorithm tries to keep things evenly spaced, but in some directions, the measurements to neighboring points might end up larger than expected. So, as a result of thinning, distances might go beyond the desired tolerance, especially in spots where the data is less dense.
If you could let me know what version of TBC you're using and share the point cloud data, I'd be happy to help more.
R
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Ramin Rad
Original Message:
Sent: 11-06-2024 23:44
From: Marek Lepkowski
Subject: Point Cloud Sampling issue
Hi All,
I noticed some issuses with point cloud sampling...
I have some scans from SX12 and i would like to sample point cloud to 0.10m
Screen of original cloud below. measured distance between points around 0.24m
After sampling i got something like this :
Why TBC is sampling points where distance are bigger than my expected value??
Point cloud around 26 000 000pts
Algorithm of sampling set to 100 000 000pts
Help please !
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Marek Lepkowski
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