[GRASS-user] Trento3D screenshots redone

[Markus Neteler]

On Thu, May 18, 2006 at 12:57:56PM -0400, Thomas Adams wrote:
> Markus,
> 
> Very, very nice! Is there a tutorial on how this is done? 

That's pretty easy:

- get 2D building polygons with heights as attribute column (v.in.ogr)
- get DEM (r.in.gdal)
- get orthophoto (r.in.gdal)
- interpolate dem to highres (I used 2m pixels) with r.surf.rst
- extrude 2D buildings to 3D (v.extrude, give building heights attribute
  column as option and 2m DEM as elevation)
- start nviz with 
  nviz dem2m vect=buildings3d col=orthophoto

that's it!


> If not, is it 
> possible to use the Trento dataset to create one? One possible use ? if 
> other details can be worked out ? is to create maps of flood inundation 
> to show buildings affected by flooding. 

OK, I couldn't resist :-)

 http://mpa.itc.it/markus/grass61/demos/rlake/
 -> see at bottom for new screenshot with flooding
    (needs r.lake which is still not in CVS...)

> I understand one must have the 
> building data (how was *that* obtained?).

The Trento municipality was going out and digitizing all builings.
Another option is to digitize building footprints from orthophoto
(v.digit) and assign a typical height to each building.

If you are lucky, get 3D DXF buildings and import them with
the recently updated v.in.dxf.

> This type of presentation is 
> very effective in capturing the imagination (as it were) of those 
> possibly affected by flooding.

Fully agreed and done. Except for r.lake everything is in
6.1-CVS.

Only the merge of the flood map with orthophoto could be better
(r.mapcalc will kill the color table, r.patch as well). In February
I did a trick in nviz (see earlier flood screenshots) which I
don't remember today (maybe I loaded the DEM twice or so).


Best,

 Markus

> Regards,
> Tom
> 
> Markus Neteler wrote:
> >Hi,
> >
> >I have re-done the screenshots of Trento3D (based on
> >2D building footprint polygons, extruded with v.extrude):
> >
> >http://grass.itc.it/grass61/screenshots/index.php
> >
> >Now the correct building heights are used.
> >Still have to add the 3D trees :-)
> >
> >Markus
> >
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> 
> 
> -- 
> Thomas E Adams
> National Weather Service
> Ohio River Forecast Center
> 1901 South State Route 134
> Wilmington, OH 45177
> 
> EMAIL:	thomas.adams at noaa.gov
> 
> VOICE:	937-383-0528
> FAX:	937-383-0033
> 
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-- 
Markus Neteler     <neteler itc it>       http://mpa.itc.it
ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18        -       38050 Povo (Trento), Italy