[GRASS-user] 3D Geometry and multiple import

GRASS GRASS user
1

Hi, All
Thank for your support on my previous problem with v.digit and nviz.
In fact, I reinstall Tiger again and GrassGIS 6.3 with all framework,
and all the problem is gone. Moral of the story, be careful with your
system configuration (for those who run on MacOS).
However, I have new basic question, in Grass GIS in principal :
When importing 3D model using v.in.dxf, is Grass support multiple
import with the same location?
I am dealing with city model, and I want to import each of 3D building
into grass, instead of using extrude facility. I already had site plan
georeferenced in Grass as vector map, and I want to place 3D model
from CAD software to each building's lot . Is it possible?
Any comment would highly appreciated.

Thank you.

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Regards,
Aswin Indraprastha
Graduate Student on Design Computing
Urban Design Science Lab
Faculty of System Engineering
Shibaura Institute of Technology
307 Fukasaku Minuma-ku Saitama-City, 337-8570 JAPAN
Tel:+81-48-687-5838 Fax:+81-48-687-5199
http://aswinindraprastha.wordpress.com

2

aswin indraprastha wrote:

However, I have new basic question, in Grass GIS in principal :
When importing 3D model using v.in.dxf, is Grass support multiple
import with the same location?

Sorry I don't quite understand, could you explain more what it is you're after?

ie What does the DXF input look like?

Multi layers in DXF file? Do you mean the same x,y,z location in space or as in
GRASS's mapset location?

I am dealing with city model, and I want to import each of 3D building
into grass, instead of using extrude facility. I already had site plan
georeferenced in Grass as vector map, and I want to place 3D model
from CAD software to each building's lot .

Are the DXF coordinates at all georeferenced? If not, you will have to use
v.transform to do it. (see also the new tcl/tk georeferencing tool)
If the coordinates are correct but e.g. negative, it's an easy job with
v.transform.

Maybe you could write a script to create v.transform params between selected
footprint and input building? Use a Machine Vision shape matching algorithm?

Is it possible?

I have imported a large DXF with v.in.dxf for NYC:
http://bambi.otago.ac.nz/hamish/grass/screenshots/nyc3d_nviz3_midtown.png

(but not 1 building at a time!)

Hamish

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3

Sorry if my question is not quite clear.
I want to build an campus area in GrassGIS. My primary 3Dmodelling is Sketchup.
Since there is no detailed geo-referenced map in my case, I begin to
develop base map by rectifying scanned map from existing vector map.
It was campus site plan. So now, I have vector map of campus plan in
Grass GIS.
How do I assign each building so that if I import into Grass, they fit
exactly to their position in vector map (site plan)?Of course,
SketchUp does not have coordinate system.
It is important for me because I want to build attribute on each
building using Postgresql connectivity (spatial database).
I have not try v.transform yet.
I had looked your NY map, how you import different 3D shape of
building into Grass?

Thank you again for your kind support.

4

aswin indraprastha schrieb:

Sorry if my question is not quite clear.
I want to build an campus area in GrassGIS. My primary 3Dmodelling is Sketchup.
Since there is no detailed geo-referenced map in my case, I begin to
develop base map by rectifying scanned map from existing vector map.
It was campus site plan. So now, I have vector map of campus plan in
Grass GIS.
How do I assign each building so that if I import into Grass, they fit
exactly to their position in vector map (site plan)?Of course,
SketchUp does not have coordinate system.
It is important for me because I want to build attribute on each
building using Postgresql connectivity (spatial database).
I have not try v.transform yet.
I had looked your NY map, how you import different 3D shape of
building into Grass?

Thank you again for your kind support.
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Hi,

I also tried to import some Sketchup data into GRASS. I know it is a mass that those dxf-files contain no xy-values ;-). Unfortunately, the only software I know solving this problem is ArcGIS, they have a sketchup-plugin for export and in Sketchup you can export your model as Esri-multipatch. This way, the data would not loose the xy-values and database connection (and it would contain texture-information), so each building on your campus area would fit on its place.

So the solution I know was posted to the mailing-list a few weeks ago:
- 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

I'm pretty knew to GRASS, so I'm sorry I can't help you much. I thought about trying with OssimPlanet, but as I learned Ossim requires gdal1.3.2, which means to deinstall gdal1.4, required for GRASS.... No way! :wink:

So I also think the only way handling this sketchup-data is to georeference each building / group of buildings, like it was already said.
Maybe there are any developement plans aiming in that direction (e.g. a sketchup or another 3D-modelling program plugin)?

Regards,

Hajo

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