[vtkusers] Using Unstructured Grid...

[Nick Ton]

Hello,

I am new to VTK. I have purchased the book and read a good portion on Data
Objects. 
I have a particular visualization project where I've created triangles from
DTED (Digital Elevation Data) 
data, I call them Trixels. I have been able to verify that my Trixels are
oriented properly on
a 2D surface using an commercial product called ESRI ArcView. I would like
to use VTK
to visualize my Trixels in 3D space. I believe that a Structured Grid or
Unstructure Grid will
be the best Data Object representation, however I am not sure how to go
about it. My Trixel
data type represents a triangle in 3D space define by it's vertices. Each
vertex
is a 3D point represented as x,y,z in Earth-centric Rotating Coordinate
(ECR). So my questions
are:

1. How do I specify a coordinate system so that I can account for the ECR
coordinates in VTK?
2. Can I create triangles and insert them into an UnstructuredGrid? If so,
any examples?

Thanks for any advice?
Nick