Thank you Michael, now my question reduces to:
- can I add 3D object like a sphere? or can I
import VRML or OpenGL files?
I know there is a 3D vector format, what can
I define with it?
Many thanks
Maria Jose Abasolo
--- Michael Ash <mash@econs.umass.edu> escribió: > >
I'm a new user of GRASS. I need someone to ask me
> the following:
>
> - is possible or usefull to use GRASS to store
and
> manipulate images. What is the advantatge od
using
> GRASS instead just PostgreSQL? or PostGIS?
>
> - can I have several levels of an image, i.e. one
> level with the original image, the other level
> with color segmentation of the original image.
The answer to both these questions is that GRASS
will meet your needs well. I use GRASS for other
purposes (mostly spatial averaging and other spatial
statistics. So I can't tell you how,
BUT I strongly recommend the book by M. Neteler and
H. Mitasova http://mpa.itc.it/grassbook/ which has a
chapter dedicated to image processing.
Best regards,
Michael Ash
> - how can I add 3D scenes? does GRASS accept
> OpenGL or OpenInventor format?
I don't know.
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On Monday 09 December 2002 10:56 am, Maria Jose Abasolo wrote:
Thank you Michael, now my question reduces to:
- can I add 3D object like a sphere? or can I
import VRML or OpenGL files?
I know there is a 3D vector format, what can
I define with it?
3D vectors are introduced in Grass51. Currently only non vertical
polygons (like TIN) may be generated from usual grass boundaries
(area edges). My plan is to add 2 new vector types:
- face (closed polygon, faces form polyhedra (volume))
- core (identifier for volume formed by faces, 3D equivalent for centroid)
In near future, I don't plan full support for this features,
because it is a bit difficult to build polyhedron from faces,
but it will be possible to import and display in nviz.
This is important if vertical polygon (like wall) is required.
Other primitives like cube or sphere are not planned because such
types are not general enough (as we don't have rectangles and circles
in 2D).
Does anybody have experience with 3D vector volumes (polyhedrons)?
Radim
> - can I add 3D object like a sphere?
Yes. Spheres and 3D diamonds..
You can draw a sphere by displaying in NVIZ a sites file with the sphere's center as each point. Create a new constant surface (Panel->Surfaces), set transparency to full, and raise or lower the surface to your desired elevation with the Position button. Then Panel->Sites, load the sites file, and tell it to use the sphere, set the size, color etc.
g'luck