How to build vtkPolyData based on the information within a txt file
문제
I have a txt file which contains a set of 3 Dimensional data points and I would like to create a vtkPolyData based on those points.
In the file, I have the number of points on the first line, in my case they are 6 x 6. And after that the actual coordinates of each point. The content of the file is like this.
6 6
1 1 3
2 1 3.4
3 1 3.6
4 1 3.6
5 1 3.4
6 1 3
1 2 3
2 2 3.8
3 2 4.2
4 2 4.2
5 2 3.8
6 2 3
1 3 3
2 3 3
3 3 3
4 3 3
5 3 3
6 3 3
1 4 3
2 4 3
3 4 3
4 4 3
5 4 3
6 4 3
1 5 3
2 5 3.8
3 5 4.2
4 5 4.2
5 5 3.8
6 5 3
1 6 3
2 6 3.4
3 6 3.6
4 6 3.6
5 6 3.4
6 6 3
How can I build a vtkPolyData structure with a txt file with this data?
해결책
It looks to me like you have a regularly gridded series of points, right? If so, vtkImageData might be a better choice. You can always use a geometry filter afterwards to convert to polydata if you really need it that way.
- Create a vtkImageData instance.
- Set its dimensions to (6, 6, 1) (the third dimension is ignored).
- Set its data type to an appropriate type (float or double, I guess).
- Call AllocateScalars();
If in C++,
- call GetScalarPointer() and cast it to the data type set in 3.
- This pointer will point to an array of size 36. You can just fill each point as you would normally.
If in another language (TCL/Python/Java), call SetScalarComponentFromFloat on the image data, with the arguments (x, y, 0, 0, value). The first 0 is the 3rd dimension and the second is for the first component.
This will give you a grid, and it'll be far more memory efficient than a polydata.
If you want to visualize only the points, use a vtkDataSetMapper, and setup the actor's property with SetRepresentationToPoints(), setting an appropriate point size. That will do a simple job of visualization.
다른 팁
Are these examples useful? In particular, this does generation of points and polygons, so it should be possible to adapt. The core seems to be (with lots left out):
# ...
vtkPolyData shell
vtkFloatPoints points
vtkCellArray strips
# Generate points...
loop {
...
points InsertPoint $k $x0 $x1 $x2
}
shell SetPoints points
points Delete
# Generate triangles/polygons...
loop {
strips InsertNextCell $NP2
# ...
strips InsertCellPoint [expr $kb +$ke ]
# ...
strips InsertCellPoint [expr $kb +$ke ]
}
shell SetStrips strips
strips Delete
# ...