Agisoft Metashape

Agisoft Metashape => Python and Java API => Topic started by: Yoann Courtois on January 30, 2019, 06:23:25 PM

Title: Model faces not linked with model vertices
Post by: Yoann Courtois on January 30, 2019, 06:23:25 PM
Hi !

I'm currently trying to selected 3D model faces using their vertex coordinates, but I'm not able to find any link between faces (Metashape.Model.Face) and vertices (Metashape.Model.Vertex).
Indeed, the first one is included ".vertices", but it's only a tuple of three numbers (which looks to be vertices number or key) and no coordinates.
The second one is included ".coord", but no number (key ?).

Then, model vertices have coordinates but no link with faces, and so faces have no positioning informations.

Could someone help ?

Regards
Title: Re: Model faces not linked with model vertices
Post by: Alexey Pasumansky on January 30, 2019, 07:15:44 PM
Hello Yoann,

You can use the following script as a reference:
https://www.agisoft.com/forum/index.php?topic=7898.msg37698#msg37698
It selects/removed the polygons (faces) which vertices are outside the bounding box.

Looping though faces you can check the coordinates of their vertices and see, if they fit the conditions or not.
Title: Re: Model faces not linked with model vertices
Post by: Yoann Courtois on January 31, 2019, 02:10:39 PM
Hello Alexey,

After some investigations, I still don't understand how it could work like that.

At first : "checkFaceTask" is called :
Code: [Select]
def checkFaceTask(face):
    global vertices
    face_vertices = [vertices[v] for v in face.vertices]
    checkFace(face, face_vertices)

But face.vertices is just a tuple of 3 integers.
So then, "checkFace" take as parameters "face", which is a model.face, and "face_vertices", which is a list of 3 integers:
Code: [Select]
def checkFace(face, face_vertices):
    global region
    R = region.rot  # Bounding box rotation matrix
    C = region.center  # Bounding box center vector
    size = region.size
    remove_vertices = 0

    for vertex in face_vertices:

        v = vertex.coord
        v.size = 3
        v_c = v - C
        v_r = R.t() * v_c

        if abs(v_r.x) > abs(size.x / 2.):
            remove_vertices += 1
        elif abs(v_r.y) > abs(size.y / 2.):
            remove_vertices += 1
        elif abs(v_r.z) > abs(size.z / 2.):
            remove_vertices += 1
        else:
            continue

    if remove_vertices == 3:
        face.selected = True
Then how it's possible to call vertex.coord for vertex in face_vertices, because vertex become an integer, so no .coord exist

After some test in Metashape console, I got the same fail.

Regards
Title: Re: Model faces not linked with model vertices
Post by: Alexey Pasumansky on January 31, 2019, 05:49:37 PM
Hello Yoann,

Here's is simple example:
Code: [Select]
import Metashape

x_min, x_max = 100, 200
y_min, y_max = 100, 200
z_min, z_max = 100, 200


chunk = Metashape.app.document.chunk
model  = chunk.model
vertices = model.vertices
faces = model.faces

for face in faces:

face_vertices = [vertices[v] for v in face.vertices]

fit_vert = 0
for vertex in face_vertices:
v = vertex.coord
#may need to convert coordinates from internal to geographic:
#v = chunk.transform.matrix.mulp(v)
#v = chunk.crs.project(v)

if (x_min < v.x < x_max) and (y_min < v.y < y_max) and (z_min < v.z < z_max):
fit_vert += 1

if fit_vert == 3:
face.selected = True
it  selects the polygons (faces) that have all their vertex coordinates fitting some pre-defined bounds.

The definition of face_vertices includes access to the array of vertices, so it is not just a list of the indices, it already contains the Vertex elements.
Title: Re: Model faces not linked with model vertices
Post by: Yoann Courtois on February 01, 2019, 01:52:38 PM
Okey ! Thank you, now I see !

It might be great to update the API documentation, and explain that chunk.model.faces

Regards
Title: Re: Model faces not linked with model vertices
Post by: Alexey Pasumansky on February 01, 2019, 02:27:12 PM
Hello Yoann,

Basically speaking face.vertices tuple includes the indices of the related vertices and not the Vertex() class objects themselves.