[GRASS-dev] z-exag in wxnviz

Helena Mitasova hmitaso at ncsu.edu
Fri Nov 25 23:58:25 EST 2011

I would like to ask users of nviz to try out wxnviz and provide some feedback on the current settings of z-exag.
We discussed it quite a bit before it was changed, but as I am using it now, I find the new setting in wxnviz confusing.
Here is the issue (Anna, Michael, please correct me if I am wrong):

- in nviz the z-exag is set to 1 when x:y:z=1:1:1 (e.g. assuming that x,y,z are all in same units this works well for elevation surfaces). 
To highlight the topography in flat landscapes, nviz often starts with zexag set to a number higher than 1,
but you can always get to the realistic vertical view by setting zexag to 1. The problem with this approach is that when you
have latlong or some other type of data with raster values much larger than the values of horizontal coordinates
the zexag can be very small (.eg. 0.00001) which is not very convenient.

- in wxnviz to avoid the very small zexag for latlong, zexag is set to 1 for z-exageration that looks good (I did not check 
how the "good" is computed) which makes for a good start for most data. Problem is that now it is not possible 
to tell what the actual vertical scaling is. For example, for most of my data (including nc_spm_08) I now have 
to drag z-exag to anywhere between 0.2-0.4 to get realistic looking surface and I am not sure whether I am making 
the surface flatter than it is in reality or when I am getting it  right (the real x:y:z=1:1:1). 
If the new behavior is preferable, should we at least have some indicator (perhaps along the slider) of what the true vertical scale is?
Or should we go back to nviz setting or even more back to SG3d setting where if I remember correctly
it started with x:y:z=1:1:1?


On Nov 25, 2011, at 10:22 AM, Anna Kratochvílová wrote:

> Hi,
> On Tue, Nov 22, 2011 at 10:42 AM, Martin Landa <landa.martin at gmail.com> wrote:
>> Hi,
>> the latest wxNviz is available only in trunk. Together with Anna we
>> are planning in these days backport to devbr6 and immediately after
>> releasing 6.4.2 to backport wxNviz to `relbr64` to have enough time
>> for testing. So at this point I will disable wxNviz in `relbr64`.
>> Martin
> wxNviz is now in 6.5, testing welcomed
> Anna

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