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

GRASS GRASS user
1

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

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

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

Thanks and Regards

Nagesh

2

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@gclements.plus.com>

3

Hopefuly this will be fixed in GRASS 7, as vertical units are in GRASS 7 idea
page (http://grass.gdf-hannover.de/wiki/GRASS_7_ideas_collection).

Maris.

On Friday 14 July 2006 12:27, Glynn Clements wrote:

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.