Calculate Point Cloud Density for UAV

[Heng Kimhak]

Hello everyone! I'm a beginner in photogrammetry. I got a UAV point cloud data in e57 file with some requirements which I really dun understand such as:
1. The X, Y, Z of the control point is within ± 10 cm
2. Point cloud density groundbreaking survey 0.25m2 /point
3. Point cloud density As-built measurement 0.10m2 /point

So I have some questions and hopefully some of you in this group can help me.
1. What is the target observation accuracy? How to calculate it? What is the use of it?
2. What is the point cloud density? How to calculate it? What is the use of it?
I'm currently using Cloud-Compare since it's an open source and free. I'm getting to know it early so there is many features that i dun know and understand. If someone experienced this before, which software did you use to accomplish all the tasks? Is it possible to use only Cloud-Compare when working on point cloud data?

Thank a lot.

[daniel]

1. I guess you would need some ground-truth / high accuracy data to compare your cloud to?

2. You can use the 'Tools > Other > Compute geometric features' tool (https://www.cloudcompare.org/doc/wiki/i ... c_features)

[Heng Kimhak]

Thank Daniel for replying me. The UAV data that I have right now are the ground breaking / actual point cloud and ready-measurement / edited point cloud. And the data to be created is Construction surveying / finished shape measurement point cloud data creation. I'm just not sure about these requirements:
1. The X, Y, Z of the control point is within ± 10 cm
2. Point cloud density groundbreaking survey 0.25m2 / point
3. Point cloud density As-built measurement 0.10m2 /point
Hopefully you can explain me and show me some feature to use in CloudCompare.

Here is the ground breaking / actual point cloud:https://drive.google.com/file/d/1NGcvbE ... sp=sharing

Here is the ready-measurement / edited point cloud:https://drive.google.com/file/d/1mBzWEf ... sp=sharing

[daniel]

Hum, not sure...

1. Not sure what are your GCP, and how you captured them, but the way you captured them should give you some confidence about their accuracy. I don't see how CloudCompare can help here.

2 & 3. Well, I guess you can just run the 'Tools > Other > Compute geometric features' tool with the 'Density > Surface density' feature for instance (with a big enough radius) and check that most of the points have at least the required density?

Another option is to use the Raster tool with a step of 1m for instance and then export the grid as a cloud with the 'population' (per cell) scalar field. And then check that you have at least 16 or 100 points for most of the cells.