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Parameterization Quantities

A parameterization is a set of 2D coordinates associated with a mesh, often referred to as “UV coordinates”. This sections details several functions for visualizing such parameterizations.

param_demo

Example:

import numpy as np
import polyscope as ps
ps.init()

N_vert = 100
N_face = 250
vertices = np.random.rand(N_vert, 3) # (V,3) vertex position array
faces = np.random.randint(0, N_vert, size=(N_face,3)) # (F,3) array of indices 
                                                      # for triangular faces
ps_mesh = ps.register_surface_mesh("my mesh", vertices, faces)

# parameterization per vertex
param_vert = np.random.rand(N_vert,2)
ps_mesh.add_parameterization_quantity("rand param", param_vert, enabled=True)

# parameterization per corner
param_corner = np.random.rand(ps_mesh.n_corners(),2)
ps_mesh.add_parameterization_quantity("rand param corner", param_corner, defined_on='corners')

# use options to customize visualization
ps_mesh.add_parameterization_quantity("rand param corner2", param_corner, defined_on='corners',
                                       coords_type='world', viz_style='local_rad')


# with custom checker/grid color
cA = (0.1, 0.2, 0.3)
cB = (0.4, 0.5, 0.6)
ps_mesh.add_parameterization_quantity("rand param corner3", param_corner, defined_on='corners',
                                       coords_type='unit', viz_style='grid', grid_colors=(cA, cB))

# view the mesh with all of these quantities
ps.show() 

Adding

SurfaceMesh.add_parameterization_quantity(name, values, defined_on='vertices', coords_type='unit', enabled=None, viz_style=None, grid_colors=None, checker_colors=None, checker_size=None, cmap=None)

Add a parameterization quantity to the mesh.

  • name string, a name for the quantity
  • values an Nx2 numpy array, coordinates at vertices/corners
  • defined_on one of 'vertices','corners', is this a coordinate per vertex or per corner?
  • coords_type string, one of 'unit', 'world' (see below)

Additional optional keyword arguments:

  • enabled boolean, whether the quantity is initially enabled (note that generally only one quantity can be shown at a time; the most recent will be used)
  • viz_style string, one of 'checker', 'grid', 'local_check', 'local_rad' (see below)
  • grid_colors 2-tuple of rgb colors, used to color the grid visualization
  • checker_colors 2-tuple of rgb colors, used to color the checkerboard visualization
  • checker_size float, the size of checkers/grid/stripes
  • cmap string, which colormap to use

if not specified, these optional parameters will assume a reasonable default value, or a persistent value if previously set.

Options

Styles

Several styles are available for how a parameterization is displayed.

The viz_style option determines how parameterizations are visualized:

  • checker: a two-color checker pattern
  • grid: a two-color grid with thin lines
  • local_check: a checkerboard over a radial colormap, centered around (0,0)
  • local_rad: distance stripes over a radial colormap, centered around (0,0)

Types

The coords_type options determines how parameter coordinates are interpreted for scaling:

  • unit: UV coords are assumed to lie on the [0,1] interval
  • world: UV coords are assumed to be scaled like the world-space positions of the mesh