Hi! I'm no expert, but have experimented with this sort of thing. As far as 
I know:

OsmAnd's elevation data comes from the NASA SRTM/ASTER data that is 
available freely for the whole world except towards the poles. This has a 
horizontal resolution of 1 arc-second, about 30 metres. The vertical 
accuracy varies but seems to be no better than +/-5m. So it doesn't make 
sense to have contour line spacing too close.

OsmAnd's contour lines are pre-computed in the download, rather than being 
generated dynamically on your device from raw elevation data, so you can't 
try closer spacing just by tweaking the rendering styles.

Many countries are providing open access to more accurate DTM/DEM data from 
LIDAR surveys. In the UK we have this only for flood modelling, which if 
one's interested in hills is the opposite of what one wants! LIDAR data can 
be amazingly accurate, e.g. you can see the shape of a car. If you have 
such data, you can generate your own contour lines in QGIS and get them to 
show in OsmAnd. If you're interested I could post some notes I made when I 
tried it, but it requires a little dedication. I found that I could now see 
features such as cliffs and quarries that had not been marked as such on 
OSM, but for me it wasn't worth the large file sizes of what I had 
generated. That was three years ago when OsmAnd's minimum spacing was 10m - 
I hadn't noticed that the "high" setting now gives 5m. This shows my 
missing quarries, but must be the limit for SRTM data. (Unless OsmAnd is 
now tapping in to LIDAR? I can't find any information on that.)

Just google any of the terms I used if you're not familiar! I hope that's 
of interest.

On Thursday, July 9, 2020 at 7:53:18 PM UTC+1 mika.va...@gmail.com wrote:

> So i live in the Netherlands, and the landscape is pretty flat here. 
> However we still have some small relief in the landscape. Most of these 
> little hills are no more then 20m but they can be pretty steep. Therefore i 
> would like to have contour lines to better estimate the terrain. However, 
> the standard contour lines in Osmand only come in three set intervals, Low, 
> medium and high. I beleive the high setting displays the contour lines at 
> 5m, but this is still not enough. Is there a way to get these contour lines 
> to display at a custom interval, like 1m? is this maybe possible by editing 
> the rendering file? i would love to hear back from you guys!

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