[GRASS-user] d.nviz : Can this GRASS module be used with lat/lon raster data?

[Glynn Clements]

Nagesh Bhatkar wrote:

> Looking at the source code of d.nviz , I assume d.nviz can only be used 
> with UTM data.

That's incorrect.

>  e1 = D_d_to_u_col((double) screen_x);
>  n1 = D_d_to_u_row((double) screen_y);

Whilst the "u" originally stood for UTM, it actually refers to the
coordinate system of the current location, regardless of the
projection used.

> Is there a d.nviz add-on module available for use with lat/lon raster data?
> or will i need to modify the code myself for use with lat/lon data

A few modules assume that the units used for map coordinates are the
same as those for elevation values. Normally, both are metres, or
occasionally feet. If map coordinates are in degrees, and elevation in
metres or feet, assuming equivalence will result in slopes being
exaggerated by a factor of around 100,000:1.

-- 
Glynn Clements <glynn at gclements.plus.com>