[GRASS-user] Create 3d models of buildings for use in Google Earth

[Maciej Sieczka]

Intengu Technologies wrote:
> I have seen the following posts, 
> http://grass.itc.it/pipermail/grassuser/2006-May/034214.html and 
> http://grass.itc.it/pipermail/grass-dev/2006-June/023820.html
> 
> I have access to orthorectifed high res imagery of towns and would
> like to start creating 3d models of buildings - would actually
> prefer to automate this process as much as possible. I do not have
> access to polygons of buildings with height. Once models are created
> they will be viewed on GoogleEarth.
> 
> On the web I found out about a product callled SilverEye from
> Geotango - has since been bought by Microsoft :(  -  product info
> was saying SilverEye extracts 3d building models from single scene
> images.

Only from Quickbird and IKONOS, using "a rational function model (RFM)
defined with 78 rational polynomial coefficients (RPCs). The required
RPC parameters are provided with IKONOS and QuickBird imagery." [1]. As
 I understand it, using these data orthorectification is performed and
DTM created. So the ortho image is an output, not an input.

I don't think it is possible to extract elevation from any
ortho-imagery. Ortho-image is as "flat" as any map.

> Any ideas  on how I can then create 3d Models from imagery using OSS
> tools.

>From stereo aerial imagery - Efoto [2]. It seems (just a brief check)
that OSSIM [3] can make use of RPC.

[1]http://www.tec.army.mil/TD/tvd/survey/SilverEye.html
[2]http://www.efoto.eng.uerj.br
[3]http://www.ossim.org/

Maciek