P.F. 2017

Skvělé vyhlídky do budoucna i v roce 2017 !
land

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Overlay WMS on 3D maps on iOS

After more than 3 years it still amazes me how  good is  myVR  technology  for 3D  maps on  iOS.  Watch Czech Republic DMT with CUZK orthophoto as base map  and cadastral or geography WMS overlay:

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iKatastr2 aktualizace na App Store

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iKatastr2  update je na  App Store !  Diky všem, kteří jej používají  a podporují tento projekt. Těší mě, že se aplikace hojně používá – a to byl také hlavní důvod aktualizace aplikace.

Tento update  je  udržovací – obsahuje rekompilaci na nejnovější iOS a zároveň stále podporuje iOS od verze 6.   Byla aktualizovaná knihovna Google Maps SDK a opraveny drobné chybky.  Můžete zde napsat své názory, komentáře a ještě lépe přímo na App Store iKatastr2 ocenit – to je jediná měna, kterou  můžete za aplikaci, která je zdarma “zaplatit” – a věřte, že každý pozitivní ohlas dodává vývojáři palivo, smysl a chuť v tom pokračovat a třeba i něčím novým překvapit :)

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Hybrid vs Native

It has been a while since my iOS native development. Just came across this report on the subject of native vs hybrid : Native vs Hybrid . Interestingly enough I have expected clear recommendation for hybrid as today devices are more capable of handling rich HTML/JavaScript content and iOS native bridges enable nice integrations with these two worlds.

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PC web vs. Mobile app usage

This chart shows real usage (sessions)  of iKatastr app over 5 years of running  as app on iOS, Android and on PC as web page  in CZ.  Tiny Windows Store app  and  Windows Phone app usage couldn’t be rendered at all.

ikatastrSessions

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Google Trends – close to reality ?

or no ? … how to explain this picture ? iKatastr was indeed attempt to introduce new term for accessing cadastral data in Czech Republic, and it launched on iOS, Android and web 5 years ago, no public advertising, no ads at all…  Anyway I like this picture, and it is kind of surprising that GISCloud nor mangomap doesn’t enjoy the same level of trending according to Google Trends. I think reality is different

 

googlwTrends

..let’s look on another measure – site visits using simlarweb.com

similarweb

similarwebmango

Looks like Google Trends takes into consideration # of visits and is more weighted than media coverage ? Or does the mobile presence of app iKatastr adds so much ‘ads’ to the final chart  ?

 

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Průkopníkům

…před 20 lety jsem tuto knihu  našel na stole v jednom starém, opuštěném  domě v Brně, dodnes se k ní vracím jako k pokladu…

pujdeto

Breviář PŮJDE TO ! ING J. SOLAR, Praha 1938, 3. vydání

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iKatastr.cz 20M clicks

First time 100K visits over month period.  20M clicks & reaching 3M sessions overall.

 

bitlystat

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Joy of Open Source

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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SVG fast scaled overlay on Leaflet 1.0 and 0.7

SVGScaled SVG can be drawn on map in much more faster way than traditional approaches, at least for points. Traditional approach re-position each element to fit into the view of the map, however SVG is “scalable” so we can use it and it performs much more faster for zoom-in/out.

Few considerations:

  1. SVG itself define viewport by its coordinate space, all outside of this viewport is usually  clipped, so it is important to keep SVG viewport in-line with the viewport of the map. There are approaches that resizes SVG as you zoom-in (here), and while it works, it has a problems in deep-zooms when you need to move on map (actually you move  giant SVG based on the zoom )
  2. translating LatLon to absolute pixel values (like here used for WebGL) is possible solution, however IE and FF has problems with large numbers for transoform (>1 M), So we need to get SVG elements in view coordinates and translate them.
  3. Having some track of bounding box of all elements like again used here should be avoided (SVG or its group element knows about extension of the elements it holds)
  4. So while we keep SVG in the viewport, we need to compensate any shift and zoom by translating <g> (group) of all elements.
  5. So in leaflet when map  moves, SVG is translated back to its original position while <g> is translated forward to reflect the map movement
  6. We need to keep track of LatLon position of either map center or one of the corner – we use topLeft corner.
  7. Leaflet doesn’t do  precise enlargement and rounds view points because of some CSS troubles on some devices (noted here). We need to patch two translating functions in Leaflet to get this right (so SVG enlargement will be aligned with map)… but I need to look on this again, best would be to not patch Leaflet of course.

most important things happen in moveEnd event:

 


 var bounds = this._map.getBounds(); // -- latLng bounds of map viewport
 var topLeftLatLng = new L.LatLng(bounds.getNorth(), bounds.getWest()); // -- topLeft corner of the viewport
 var topLeftLayerPoint = this._map.latLngToLayerPoint(topLeftLatLng); // -- translating to view coord
 var lastLeftLayerPoint = this._map.latLngToLayerPoint(this._lastTopLeftlatLng); 

 var zoom = this._map.getZoom();
 var scaleDelta = this._map.getZoomScale(zoom, this._lastZoom); // -- amount of scale from previous state e.g. 0.5 or 2
 var scaleDiff = this.getScaleDiff(zoom); // -- diff of how far we are from initial scale 

 this._lastZoom = zoom; // -- we need to keep track of last zoom
 var delta = lastLeftLayerPoint.subtract(topLeftLayerPoint); // -- get incremental delta in view coord

 this._lastTopLeftlatLng = topLeftLatLng; // -- we need to keep track of last top left corner, with this we do not need to track center of enlargement
 L.DomUtil.setPosition(this._svg, topLeftLayerPoint); // -- reset svg to keep it inside map viewport

 this._shift._multiplyBy(scaleDelta)._add(delta); // -- compute new relative shift from initial position
 // -- set group element to compensate for svg translation, and scale</pre>
 this._g.setAttribute("transform", "translate(" + this._shift.x + "," + this._shift.y + ") scale(" + scaleDiff + ")");

Test page / Gist : http://bl.ocks.org/Sumbera/7e8e57368175a1433791

To better illustrate movement of SVG inside the map, here is a small diagram of basic SVG states:svgpositioning

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