# how to know cylinder volume in pixels?

I have a 3D point cloud representing ad object. I use a 3D cylinder to fit this object in the point cloud, so I check if each point is inside the cylinder and, if it is, then I assign a weight to that point.

So, at the end I have an estimate of how many points fall inside the cylinder and what is the weight of the fitting.

Now I would like to normalize the fitting dividing for the cylinder volume but this is in decimeter so the proportion I think it is not right. I think I can't count and weight points and divide them for a metric number. I think that I have to transform the metric volume into the "number of points that the cylinder can contain". This is just an idea of mine.

But how can I do so? Do you have any other idea?

• I have retagged the question since it is not about the finite volume method. – Shuhao Cao Mar 20 '13 at 18:21

## 1 Answer

As you mention you cannot devide by a metric, i guess you want a unit-less outcome.

As the volume of a cylinder is always going to be cubic meters (decimeters or any scalefactor can be applied) you will need to devide it by something with the same dimension.

Some options:

• The smallest cylinder that can hold the cloud
• The smallest cube/sphere that can hold the cloud
• The smallest cube/sphere that can hold the cloud
• The size of the range in which the points can occur