Timeline for Verification of map scale
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Aug 19, 2021 at 14:15 | comment | added | Vince | "Far away from the equator" is the issue. Every row in Web Mercator has a different pixel size, each one getting larger away from the Equator (when the globe actually gets smaller). | |
| Aug 19, 2021 at 14:14 | comment | added | Ian Turton | Another thing to check is if your screen pixels are really .28x10-3 metres across | |
| Aug 19, 2021 at 14:08 | history | edited | Vince | CC BY-SA 4.0 |
tyop; nsminh
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| Aug 19, 2021 at 14:05 | comment | added | theDrifter | @Vince this map convers a world region far away from the poles or the equator. In this case quite usefull | |
| Aug 19, 2021 at 13:58 | comment | added | theDrifter | @IanTurton the pixel size matches now the calculated size of 0.07m. This does relate to the image pixels and therefore the data - and should be independent from the device used for displaying the data. So i do not understand where this difference comes from | |
| Aug 19, 2021 at 13:55 | comment | added | theDrifter | @Erik yes i tried and the result match the calculated value | |
| Aug 19, 2021 at 13:52 | history | edited | theDrifter | CC BY-SA 4.0 |
further tests
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| Aug 19, 2021 at 12:43 | comment | added | Vince | Calculating scale based on Web Mercator is an exercise in futility, since distances off the Equator can't be accurate (and approach infinitely inaccurate at the poles). | |
| Aug 19, 2021 at 10:03 | comment | added | Ian Turton | Just because the server will serve data with that resolution it doesn't mean that the data itself is that resolution, i.e. there can be many screen pixels to the image pixel. | |
| Aug 19, 2021 at 8:40 | comment | added | theDrifter | Ah no, good point. I ll try that with QGis | |
| Aug 19, 2021 at 8:38 | comment | added | Erik | Have you tried loading the WMTS into a GIS, zoomed completely in and then measured the resolution/pixelsize? | |
| Aug 19, 2021 at 8:20 | history | asked | theDrifter | CC BY-SA 4.0 |