Die Vermessung und Darstellung aller Welten

At my heart, I am a cartographer ....

[cartographerchronicles-blog]

New Server

So I am setting up a new server. I will not use the Amazon AMI any more, but my own device. This is an old core2duo laptop, 32 bit, equipped with 2 GB RAM. I might update it later. I wanted to get rid of PHP - I found a promising PHP alternative : Slash. The github repos can be found here

Choosing an Arch Based OS for i686 I want to use a Arch based OS, because of the excellent AUR.  Chakra, Frugalware and KaOS are out of question, because they do not come with direct AUR support. Enlisy sounded great, but is very very old. Archbang, Antergos and Bridge were unable to support my network card. I did not want to use the sedcurity of Android themed distros. I looked if openSuse or a derivative of it would felicitate quick installation from AUR, but no. So choices are Manjaro or a derivative thereof. My experince with Manjaro is that their support is rather less good. So I opeted for Netrunner, my current workhorse. But I failed to install it on my old box, dont know why. Probably because the installer won’t accept a NTFS partition. Then I found this. This probably won’t stay long, but I will get started with this. After installation, I opted for a system update, but few events happened. The PGP key from Antonio Rojas could not be imported. I resolved that by

pacman -S archlinux-keyring

Then some packets of the update had a different signature, and could not be installed. I resolved that by

pacman -S manjaro-keyring

During the update of XFCE components, the machine rebooted, and I could not proceed any further - xfce won’T log in. So I logged in the KDE desktop - the internet was autoconnected, and I did not ahve a way to access Networkmanager - the applet was not installed. Nor could I start the XFCE-terminal (KDE is not complete in this respin, so konsole is not installed). So I logged in to the virtual console tty2. In this case tty1 is used to run X. I could finish the update process. Then I wanted to install the AUR package for slash. But it won’t - Makefile for sapi has twists. Yaourt won’t give me the usual option to edit the PKGBUILD - no idea why . So I cd-ed to the directory /tmp/yaourt-aur-pkgbuild/ etc, where the PKGBUILD is, and edited it manually using nano. I added the correction in the build() function after ./configure as discussed here - and created the package using

makepkg -s

- that worked. Then I installed it with

pacman -U packagename-i686.tar.xz

- so far so good. I installed Cherokee as server as opposed to Apache. I like its idea.

[cartographerchronicles-blog]

Review of Mango and a comparison to the UI in development

Today in my Linkedin feed : Mango is a service offering the ability to create custom maps and overlay. The features include (From the website):

Support fordifferent formats, such as : Shapefile, Raster, KML and CSV, geoTIFF

Custom layer styles and legends / color ramp (color index)

Attribute Search and Query tool.  I have not tested the query tools, so I dont know if they can perform SQL compliant searches.

The documents mention that pulling layers from a WMS is possible. Generally this won't be a problem, as long as no JS is trying to access the WMS data. A special feature includes a side by side comparison, of multiple maps. However, in my mind this misses a few aspects. You still can not pull the map image and insert it in an arbitrary diagram. You still can not apply arbitrary operations on the map. These are the points I will address in my project. Here is a picture of my UI

The idea is to seamlessly integrate Data, Arithmatic, and Arbitrary Commands in a single UI. Data itself can consist of commands such as A = 1+2 or B = load : SOME_WMS by SOME_SQL. More complex arithmatic can be referred to the Artihmatic box, such as C = get : SOME_ARITHMATIC. The "get :" command immediately refers to the arithmatic box. So you can write, in DATA : C = get : D and in Arithmatic : D = complex_expression_evaluated_by_python. I use the Skulpt for the python support. After all the loading an computation is done, the engine starts looking at the arbitrary commands which finds specific objects, applies transformations on them and/or renders them on the webGL canvas with THREE.js and Cesium What do you think? Test here. Click on button "A", to load some test data. This data will be rendered (coming soon)

[cartographerchronicles-blog]

Setting up a server - AWS

I am using AWS. I signed up for the free tier, then selected a machine in central EU, eligible for free tier. Then I created an Amazon EC2 machine. In my AWS console, i have selected EC2.

Then I click on Launch instance :

The rest is pretty straight forward : Select the Amazon AWS AMI for 64 bit, and continue as you choose. The network has to be vpc.

In the security group tab, I added ssh and http from anywhere (0.0.0.0/0). The I created a key pair with this machine, and downloaded the *.pem file. Now I can log in to the machine via ssh.

[cartographerchronicles-blog]

Setting up a Unified Web Mapping Solution

For the need of my various projects, I need an unified solution, were I can send data (that is in the text form), including embedded python code as part of the data. Then I want to query this data, based on a simple Turing Machine, and render this as different kinds of diagrams. I will possibly need to append other text data from othe web sources. Often this third party data comes as JSON. In order to render, I will need JS libraries like THREE or Cesium. The basic setup is thus :

The rendering depends on JS, and it is often necessary to load external resource in JS. The W3 consortium has decided, that nothing from an external source can be loaded into JS, unless the Cross Origin resource Sahring headers are set (see here : http://enable-cors.org/).  The only way to beat this is a Proxy server. in order to create a proxy server, you will need a server with PHP + Apache. Since we will be transporting images, the gd library needs to be installed, and allow_fopen_url needs to be set true in the php configuration. Even then, it often does not work with proxying a WMS response, probably because of some funny header or such. My solution is therefor calling the wget command in *nix systems - via exec(). I will first need a server.

[cartographerchronicles-blog]

Intro

In this blog, I will document my adventures with web mapping service and related topics.