Joy of Open Source

*** update IV/2017:  from comment below, check this great raster plug-in  from Victor Veralde Gutiérrez too: https://github.com/IHCantabria/Leaflet.CanvasLayer.Field/  ***

I have got great, absolutely amazing  joy today from my own open source experiment. In 2014, nearly 2 years ago,  I have published on GitHub (gist)  L.CanvasOverlay a small class  to handle generic drawing on top of Leaflet, I was thinking let’s try to  contribute back to the open source with this little snippet –  I thought would be useful so I have added little description. Original blog post here: https://blog.sumbera.com/2014/04/20/leaflet-canvas/

After few months later I found it is used on http://windyty.com   one of the best 2015 geo-visualization with huge popularity. It is a small part of this great app, but makes me feel so good like I am part of it, I am looking on something where is my small piece, small share…meaning of the effort, sense of publishing and open sourcing.

Screen Shot 2016-02-02 at 23.16.13

And today I have got echo it is used also in Marine National Facility here: http://www.cmar.csiro.au/data/underway.test/

This makes me so happy … and just came across this quote : “Revenue is a lagging indicator, usage is a leading indicator,” can’t remember, who just said that ? :)

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Freedom from OS lock-in

quoting from http://blogs.vmware.com/console/2006/11/changing_role_o.html
“Once you have a pervasive virtualization layer that focuses exclusively on managing all the underlying hardware and can run any OS, developers will finally be able to adapt and integrate the operating system as a part of their application, ship both of those together as a virtual machine and be confident it can run in any environment.”

Caching WMS requests

Recently I was interested in caching WMS requests on MapSnack, that would allow off-line usage of WMS sources. Unfortunately there is no functional WMS discovery or search engine. Google is very weak in this area and even inurl: doesn’t bring too many results. There is one paper I found on this topics called “OpenGIS WMS-based prototype system of Spatial Information Search Engine” but to access this paper you nee to login to IEEE. pages. So how to help google to index WMS layers and pictures it produce ? one of the thoughts I have is to create simple set of pages on which each request for certain layer for certain zoom level and in particular tile would be referenced. Tiling is important as “sampling frequency” for the WMS cache. Actually last year I was working on prototype which enabled me to save for offline use WMS tiled layers (refer to http://www.sumbera.com/news/mapajax/mapajax.htm) what was missing was an automatic crawler on the area and layers – the saving was done only by manual navigation in the area. Last note : I expect the shift of the google search engine towards this freely available geospatail content (…. just right after I will start to generate my index pages ;)

MapSnack pilot run

MapSnack runs.
thanks to Jachym Cepicky and Peter Balogh we have now 2 pilot runs of MapSnack

1st: http://mapserver-slp.mendelu.cz – serving school forest enterprise maps SLP Krtiny
2nd : http://mapsnack.mendelu.cz – serving maps of southmoravia area

all 2 virtual geospatial appliances runs on server MapBistro with VMware Server installed on Debian

The only thing which is missing there is a button for downloading MapSnack.
So kind of Web WYSIWYG :))

Reading MapSnack virtual disks directly from DVD

Today I’ve tried to access virtual disks from DVD to run MapSnack. Interestingly enough it runs, the trick is to make snapshot which can be read-only and remain on DVD – so you don’t need to copy all Gigabytes to your hardrive. Instead you copy on your HD just few MB of ‘delta’ virtual disks which need to be writable. Of course it is slower to read from DVD but for saving a disk space that make sense. So let’s consider following modes of running MapSnack: 1. virtualized and runing from harddrive (current release) 2. virtualized but mostly run directly from DVD (this) 3. native run from DVD as LiveDVD (see previous post) 4. hybrid run – native: small booting iso image which mounts virtual disks virtual: see point 2. Number 4 is target which brings great flexibility.