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Weather Related Organizations => WeatherUnderground => Topic started by: Ray Proudfoot on January 27, 2019, 12:27:23 PM

Title: WU Map - What determines station visibility as you zoom out?
Post by: Ray Proudfoot on January 27, 2019, 12:27:23 PM
Iím trying to work out if thereís any logic applied when you zoom out on the WU Map and stations start to disappear.

My own has been uploading data since May 2009 but disappears pretty quickly with another nearby station staying visible for longer despite a shorter WU life.

I continued to zoom out and another station still remained despite its records only starting on 27 Dec 2017.

The logical process should have the stations that have been uploading data the longest remaining the longest.

Anyone from WU care to comment?
Title: Re: WU Map - What determines station visibility as you zoom out?
Post by: galfert on January 27, 2019, 03:38:48 PM
I think it is just total luck but there is some logic determining that luck.

At each given level of zoom an imaginary grid is formed with a determinate size of these grid squares being larger or smaller depending on zoom level. The objective of the map is to show the most amount of stations without overlap. Then inside each of these squares a station is selected that is the most central to that given grid square. Notice no stations overlap. The purpose of the grid is to give that grid space to just one station. But it is also possible that if two adjacent grid squares have stations still too close to each other then one neighboring gird square station will win out over an adjacent one if it is more central to its square therby being shown and then then the neighboring station on the nearby grid square is then not shown. When the zoom level is change the size and location of grid lines changes. That then becomes the luck determining factor if your station is the one picked to best represent that given grid space. I've seen a different zoom levels where a station is shown then you zoom in more and it disappears and a nearby one shown instead. Again all luck as to where those stations fall into their invisible grid spaces. Realize too that the grid spaces are different for each zoom level. The grid squares do not zoom and stay static.

Bottom line is that it seems like no station is given preference. The objective of the map is to show the most amount of stations by selecting the ones with the most distance apart using these invisible grid lines.

I'm not saying this with any authority. But it is my best guess based on years of working at different capacities in the IT field. I'm just saying from a technical standpoint this would be a simple map presentation to implement. What you probably want is to use historical precedence to determine which stations to show and also to use data quality of the station to be a determining factor. That requires more work.

The old Wundermap did show some preference to older station with longer reporting history. That older map had no problem letting stations overlap each other slightly so that one station appeared on top of another station. The new map never overlaps stations.
Title: Re: WU Map - What determines station visibility as you zoom out?
Post by: Ray Proudfoot on January 27, 2019, 05:46:55 PM
Thanks galfert. Good diagnosis which does make sense. Itís just a lottery really. It would seem you have a better chance of being visible for longer by being in a remote location. That puts me at a disadvantage as I live in a suburban area with perhaps 6 stations in a 4 mile radius.

Oh well, at least my station is visible once again after the recent problems.