在postgis中存储多边形和几何

Question

I'm hardly trying to extract data o polygons from Blender to PostGIS via Python. For the beginning I'm trying all this stuff with a simple cube. At all I want to get a pure POLYGON - GEOMETRY-Type in PostGIS which looks like POLYGON((x1 y1 z1, x2 y2 z2,.....)) I can read information from Blender in this way:

The vectors:

verts=[ 
<Vector (1.0000, 1.0000, -1.0000)> ,
<Vector (1.0000, -1.0000, -1.0000)> ,
<Vector (-1.0000, -1.0000, -1.0000)> ,
<Vector (-1.0000, 1.0000, -1.0000)> ,
<Vector (1.0000, 1.0000, 1.0000)> ,
<Vector (1.0000, -1.0000, 1.0000)> ,
<Vector (-1.0000, -1.0000, 1.0000)> ,
<Vector (-1.0000, 1.0000, 1.0000)> ,
 ]

and the faces (the numbers are the vertices which form a polygon):

faces = [
(0, 1, 2, 3)
(4, 7, 6, 5)
(0, 4, 5, 1)
(1, 5, 6, 2)
(2, 6, 7, 3)
(4, 0, 3, 7)
]

Now I don't know how to get this information into a POLYGON-GEOMETRY-structure to store it in PostgreSQL/PostGIS.

In the end I want a POLYGON((...)) for each face of the cube. And I want to do this for more complex 3D-models out of Blender. With POLYGON- or TIN-GEOMETRY.... But at first I need to know how to interact with the geometries with Python.

I hope you can get me a little further. I'm thankful for any hint. Thanks! J

Answer 1

I am not quite sure about the Blender's internal object model so I have created some dummy data for that. But I think the end result should be close to what you are looking for:

verts = [[1.0,-1.0,0.0]]*8
faces = [
    (0, 1, 2, 3),
    (4, 7, 6, 5),
    (0, 4, 5, 1),
    (1, 5, 6, 2),
    (2, 6, 7, 3),
    (4, 0, 3, 7),
]

# ---------------------------------------------
# PostGIS POLYGON data formatting happens next

for f in faces:
    print("POLYGON((", end="")
    for point in f:
        v = verts[point]
        print("{} {} {} ".format(v[0], v[1], v[2]), end="")
    print("))")

# Will print....

# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))
# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))
# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))
# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))
# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))
# POLYGON((1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 1.0 -1.0 0.0 ))