[pdal] Eigenvalues for .las Data

[Bradley Chambers]

It is the covariance of the XYZ coordinates alone.

On Mon, Jul 8, 2019 at 12:47 PM Joseph S Faraguna <faraguna at mit.edu> wrote:

> Hi everyone,
>
> I am wondering what matrix is passed into Eigen's SelfAdjointEigenSolver
> <https://eigen.tuxfamily.org/dox/classEigen_1_1SelfAdjointEigenSolver.html>
> when filters.eigenvalues is called on a .las file. The
> filters.eigenvalues documentation states that the decomposition is
> performed for each point with knn nearest neighbors, but to my
> understanding decompositions can only be performed on square matrices. I
> was originally imagining a matrix of points like
>
> [x0 x1 x2 x3 ... xknn]
>
> ]y0 y1 y2 y3 ... yknn]
>
> [z0 z1 z2 z3 ... zknn]
>
> but this would definitely not be square. Is it a covariance matrix for all
> points, kind of analagous to PCA?
>
> Best,
>
> Joe Faraguna
> _______________________________________________
> pdal mailing list
> pdal at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/pdal
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/pdal/attachments/20190708/d6ecf22c/attachment.html>