Geodesic in slam

# Authors:
# Guillaume Auzias <guillaume.auzias@univ-amu.fr>
# Julien Barrès <julien.barres@etu.univ-amu.fr>

# License: MIT
# sphinx_gallery_thumbnail_number = 2

NOTE: there is no visualization tool in slam, but we provide at the

end of this script exemplare code to do the visualization with an external solution

---

Importation of slam modules

import slam.io as sio
import slam.geodesics as sgeo
import numpy as np
# import trimesh

Mesh importation

mesh = sio.load_mesh("../examples/data/example_mesh.gii")

Getting the vertex index in specified geo_distance of vert

vert_id = 200
max_geodist = 10
geo_distance = sgeo.compute_gdist(mesh, vert_id)
area_geodist_vi = np.where(geo_distance < max_geodist)[0]
print(area_geodist_vi)

[  11   35   44   47   50   51   52   55  145  147  151  152  159  170
  171  173  174  175  176  182  183  184  191  192  193  199  200  212
  213  219  223  233  334  354  357  722  723  724  735  736  737  739
  749  750  752  761  786  787  803  823  832  864  867  897  899  901
  920  922  932  933  934  936  945  969  978  979  980  982  983  992
  993 1001 1002 1003 1004 1011 1012 1019 1030 1037 1864 1887 1888 1889
 1890 1920 1931 1932 1941 1942 1943 1944 1945 1961 1962 1963 1964 1965
 1966 1967 1968 1985 1986 1987 1988 1989 1990 2001 2002 2003 2004 2005
 2006 2007 2018 2019 2020 2021 2022 2023 2024 2025 2028 2029 2042 2047
 2069 2070 2071 2075 2076 2077 2078 2080 2095 2109 2110 2111 2141 2150
 2151 2152 2169 2170 2180 2181 2182 2183 2194 2195 2196 2207]

Getting the vertex index in specified geo_distance of vert

area_geodist = sgeo.local_gdist_matrix(mesh, max_geodist)

Get the vertex index

indices = []

for i in range(mesh.vertices.shape[0]):
    vert_distmap = area_geodist[i].toarray()[0]
    area_geodist_v = np.where(vert_distmap > 0)[0]
    indices += [area_geodist_v]

Arbitrary indices of mesh.vertices to test with

start = 0
end = int(len(mesh.vertices) / 2.0)
path = sgeo.shortest_path(mesh, start, end)
print(path)

[0, 1506, 1511, 1525, 1534, 1535, 1537, 1582, 1625, 311, 396, 431, 780, 830, 883, 528, 558, 569, 595, 1074, 1083, 1102, 1135, 1134, 1164]

VISUALIZATION USING EXTERNAL TOOLS

# Visualization with visbrain # show the geodesic distance visb_sc = splt.visbrain_plot(

mesh=mesh, tex=geo_distance, caption=”geodesic distance”, cblabel=”distance”

) visb_sc.preview() # show the geodesic distance locally visb_sc2 = splt.visbrain_plot(

mesh=mesh, tex=area_geodist[0].toarray().squeeze(), caption=”local geodesic distance”, cblabel=”distance”,

) visb_sc2.preview()

# Visualization using pyglet

mesh.visual.face_colors = [100, 100, 100, 100]

path_visual = trimesh.load_path(mesh.vertices[path]) path_visual

scene = trimesh.Scene([

points_visual, path_visual, mesh])

scene.show(smooth=False)