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Measure tool: 1, 2, 3 meters too rough #300

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jidanni opened this issue Sep 18, 2024 · 2 comments
Open

Measure tool: 1, 2, 3 meters too rough #300

jidanni opened this issue Sep 18, 2024 · 2 comments

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@jidanni
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jidanni commented Sep 18, 2024

The Viking Measure Tool even shows decimal degrees:

  • 123.4, 123.5 ... degrees.

But for the distance it is amazingly coarse: only showing

  • 1, 2, 3 ... meters.

...not even showing decimeters. (decimeter = 0.1 m). I think at least centimeters are needed when using the maximum zoom level.

Anyway currently one has to tug the ruler quite a long distance on the screen before the meter count finally updates. So use a centimeter count (123.45) instead please.

I recall Google Earth's measure tool is more precise. Same with iD's.

@rnorris
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rnorris commented Sep 22, 2024

This is partially by design.

Sub metre precision is unlikely to be actually that accurate - I don't envisage Viking should be used in such cases where you want that level of detail, since I'm not sure the equations work to that centimetre level of precision - especially for varying latitudes - so it's to avoid false precision accuracy.

Whereas degree accuracy can be useful across larger distances (e.g. up to 10s of KMs) - for simplicity of implementation this is just a fixed output precision; even where such precision is perhaps not so accurate for highly zoomed in levels nor perhaps that useful when zoomed out a lot.

@jidanni
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jidanni commented Sep 24, 2024

I started with a WKT POLYGON((0 0,0 5,9 5,9 0,0 0)) of a 5x9 meter house, converted it into WGS84 an viewed it in Viking.

Viking shows the dimensions perfectly, including the diagonals.

Except the user needs to reverse engineer where viking increments the unit. Apparently at 0.5, 1.5, etc

It is all very unfortunate loss of precision, for no good reason. I am sorry to say.

As far as extreme latitudes, I recall Google Earth doesn't even let one view things that far in the first place.

So that's how it gets away with centimeters or whatever.

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