Measurements within a point cloud object

[Kwanmok]

Hi,
I am trying to measure some of the characteristics of an object but don't know whether CloudCompare can do these as it was made to compare between more than one clouds of objects (?).So I thought it would be better to ask the forum whether this is the software I want to look into before getting any further. I suppose that these are simple questions and tasks for the people around here.. It would be really helpful if you could tell me whether this is do-able with this software and how to do this in CloudCompare.

1) Is there a plugin (or any way) that could capture the crevice shape (crevice or the interstitial space) between rocks (or any interstitial spaces) ? Maybe an option (or a plugin) that fills in the area of interest (interstitial space) with watershed methods (filling a space with solutions to determine its shape) or isolates the expected space (by clicking multiple points) so that I could isolate it out for further uses like measuring volume, sizes etc?

2) In addition to number 1, I was wondering if it is possible to measure the distance between one point to another. Say, if I have a point cloud of one banana and I would like to measure the distance between one end to another, how do I do this? CloudCompare is only for comparing objects?

3) Adding to number 2, how about Volume and surface area of 'one' banana point cloud?

4) Moreover, if my point cloud has blank holes, is there a way to fill the hole in this software or do I have to do it in a different software like photoscan?

Thanks in advance.

[daniel]

1) There's a method related to this that automatically create a mesh between two polylines ('Edit > Mesh > Surface between two polylines'). And to get the polylines on the boundary of your objects, there are several solution but the manual one is probably the easiest to test (with 'Tools > Trace polyline' or more indirectly 'Tools > Point list picking'.

2) You can pick two (or more points) and compute their relative distance. See the 'Tools > Point picking' tool (http://www.cloudcompare.org/doc/wiki/in ... nt_Picking)

3) Surface can be measured on a triangular mesh (Edit > Mesh > Measure surface) or with 'Facets' objects ("Tools > Fit > Facet") depending on your needs. Volumes can only be measured on closed meshes (Edit > Mesh > Measure volume) or between two points clouds ("Tools > Volume > 2.5D volume")

4) It's possible to tedious to do it with CC.

[Kwanmok]

Thank you for the reply. I have enjoyed the experience with CloudCompare however, confused a little bit at this stage.
I have some follow up questions regarding your answer for number 1..

I have managed to do what you have explained in number 1..
I have first applied the poisson surface reconstruction to the point cloud (as it helps visually where I am pointing) and then created two poly lines around the crevice of interest. As you have mentioned in your reply, I have drew two poly lines on each sides of the crevice and then applied the 'Surface between two polylines'. However, since this is simply making a surface between the polylines, this does not give information on the inside of the crevice and the created surface is floating on top of the crevice. I am looking for a way to measure the characteristics of the inside of the crevice for example, the roughness, aspect, slope, volumes, surface areas, the shape etc. For instance, the parallel example would be to measure the volumes, size, shapes of a rat hole from an image taken from the outside.

1) So, is there a way to capture the characteristics (volume, aspect, slope, shape, roughness etc.) of the hole?
2) When using a poly line option, sometimes it picks the point in the back side of the object, resulting in building a poly line that seems to be disconnected from a view from the top. Is there an easy way to make a line that captures just the top? I have tried making the mesh first (using the poisson reconstruction) hoping that it will pick points on the top, but this didn't do much help. Maybe I am doing a wrong approach? Plugin Compass had a tracking option so I used that, but the line generated can't do anything after that for example 'surface from two polylines'.
3) Is there an option that could cut out a certain portion of the cloud point (or the mesh) for example, using a rectangular box?

Thanks in advance.

[daniel]

1) I'm not sure to understand: do you have points inside the hole? If yes, then you can segment the corresponding points (if necessary, see 3) and then compute the curvature, the roughness, the dip/dip direction (slope?), ec. But I doubt you'll be able to make ALL your measurements in CloudCompare. And of course if you don't have any points then there's not much you'll be able to do...

2) Maybe increasing the size of the 'snap size'? And with a mesh, make sure to use the very last version (2.10.alpha). I believe there was a small bug in the picking process (even though it should explain why the points are picked 'behind' the mesh?). Moreover, to avoid confusions, you can hide/disable everything but the mesh.

3) You can use the 'scissors' tool (http://www.cloudcompare.org/doc/wiki/in ... ation_Tool) or the clippiing box tool (http://www.cloudcompare.org/doc/wiki/in ... ss_Section).