[josm-dev] pecision of mouseclick in josm - may be not jsom-specific

[Sebastian Klein]

Marco Lechner - FOSSGIS e.V. wrote:
> hi,
> 
> I' m wondering how precisely it is possible to click an specific point
> in josm. I mean, by clicking with the mouse at a specific point to
> generate a node, what are the factors influencing my precision besides
> the actual zoom scale and my parkinsonism?
> Are there any differences compared to flash-based potlach?
> I just want to know in theory. It's clear that you can set points worlds
> precisely enough by choosing an appropriate scale.

As Frederik said, apart from a small rounding error, the only limiting 
factor is the pixel raster, so at a scale of 5m/100px (see scale bar in 
the upper left area) you have about 5cm precision.

If you save the layer to file, it keeps the exact values. However, on 
upload the coordinates will be rounded to server precision, which is 
(IIRC, at least near the equator) worse than 5cm.

Sebastian