chambbj

First

mamba create -n qgis-build qgis --only-deps
mamba activate qgis-build
mamba install cmake winflexbison expat setuptools compilers pip
pip install pyqt-builder
cmake ..

The algorithm is described in [1]. I've started a Jupyter Notebook that outlines the steps, but for those who just want to run with it, here is a pipeline that will apply the filter. Doing it this way, it's a bit slow (think 30 minutes for about 1.4M points on my MBP), but results look pretty good - perhaps good enough to justify coding up in C++ as a new stage.

Requires PDAL built with Python support, and Python packages astropy, numpy, pandas, and scipy. The parameters S, k, n, and b could be exposed as pdalargs to be user-defined. These values were appropriate for some of the ISPRS datasets.

[1] D. Mongus, N. Lukac, and B. Zalik, “Ground and building extraction from LiDAR data based on differential morphological profiles and locally fitted surfaces,” ISPRS J. Photogramm. Remote Sens., vol. 93, no. January, pp. 145–156, 2014.

I created a docker image that applied the steps described in https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#Setup_your_system_and_account. Any time I need to update a package, I just spin the image back up.

To create a new package you could theoretically use the template instructions here https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#Use_a_template_APKBUILD, but I usually just create my APKBUILD file from scratch.

Build is pretty simple. From the package directory, just abuild checksum && abuild -r as described in https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#Build_the_package.

Regular git stuff for committing changes. https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#Commit_your_work

Alpine accepts packages submitted to the mailing list https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#Send_a_patch, or submitted as a GitHub PR (more on contributing here https://github.com/alpinelinux/aports/blob/master/.github/CONTRIBUTING.md).

We recently had a user inquire about how to split their LAS file by classification, resulting in one file with all ground returns (classification = 2) and another with everything else. While we have the filters.groupby filter that can do something very close to this, you'd actually end up with individual files for every classification present.

Now a brute force solution immediately came to mind. What if we reassigned everything but ground to a common value with filters.assign and then used filters.groupby?

{
    "pipeline":[
        {
            "type":"filters.assign",
 "assignment":"Classification![2:2]=0"

Get up and running with the PDAL Python package in just five easy steps!

First, from your host, pull and then fire up an alpine:edge container.

$ docker pull alpine:edge
$ docker run -it alpine:edge /bin/sh

Now, within your running container, add the edge/testing repository, install py2-pdal, and verify the imported PDAL version number.

	Getting Windows to boot again after switching from RAID to ACHI.

	http://triplescomputers.com/blog/uncategorized/solution-switch-windows-10-from-raidide-to-ahci-operation/

	Dell instructions basically work.

	https://www.dell.com/support/article/us/en/04/sln301754/how-to-install-ubuntu-and-windows-8-or-10-as-a-dual-boot-on-your-dell-pc?lang=en