[GRASS-dev] z-exag in wxnviz

Anna Kratochvílová kratochanna at gmail.com
Sat Nov 26 14:49:51 EST 2011

2011/11/26 Hamish <hamish_b at yahoo.com>:
> Helena wrote:
>> - in wxnviz to avoid the very small zexag for latlong,
> another idea for lat/lon z-exag: just figure out what is 20-25% of the canvas height (or ~15% of the north-south image width),
> and work backwards from there, rounding to the nearest nice
> round number.
> I don't know if there is any real way to escape from x:y:z ratios
> of 1 : 1 : 1/(1852*60), as anything other than that is numerically
> synthetic. if taking up the 1:cos(lat) aspect ratio adjustment
> perhaps rather than converting the elevation data to degrees,
> we could convert the ew, ns to "meters" to get ratios of
> 1852*60*cos(lat): 1852*60 : 1 as the cheap and dirty projection.
> for global lat/lon views you probably wouldn't want to do that
> though.
> Hamish


I think we should revert the changes in zexag, it's the only way to
set real exaggeration. Very small zexag values with lat/lon maps are
inconvenient but still it works. I like the possible solution with
1852*60*cos(lat) but I'm not sure I'll be able to implement it, I
remember I tried to do something similar but I couldn't get it work
(OGSF is quite messy). I can try again (but not now, maybe in the next
few weeks).


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