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Color Quantities

Visualize color rgb-valued data at the elements of a surface mesh.

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)

# visualize some random data per-vertex
colors_vert = np.random.rand(N_vert, 3)
ps_mesh.add_color_quantity("rand colors", colors_vert, enabled=True)

# visualize some random data per-face
colors_face = np.random.rand(N_face, 3)
ps_mesh.add_color_quantity("rand colors2", colors_face, defined_on='faces')

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

Add Colors to Elements

SurfaceMesh.add_color_quantity(name, values, defined_on='vertices', enabled=None, param_name=None, image_origin="upper_left")

Add a color quantity to the mesh.

  • name string, a name for the quantity
  • values an Nx3 numpy array, with rgb [0,1] colors at vertices/faces
  • defined_on string, one of 'vertices','faces','texture', is this data a color per vertex, per face, or texture image?

This function also accepts optional keyword arguments listed below, which customize the appearance and behavior of the quantity.

The param_name and image_origin arguments are used only if defined_on='texture'. See below for details.

Color Texture Maps

Texture images define data by storing it an image grid, and using coordinates defined on the face-corners or vertices of a mesh to sample values from the image for each point on the surface.

To visualize color data defined in texture maps, first add a Parameterization Quantity (aka UV map) defining the coordinates. Then, add a buffer of image data to be sampled from.

Example 

import numpy as np
import polyscope as ps

ps.init()

# add a mesh
N_vert = 100
N_face = 250
vertices = np.random.rand(N_vert, 3)
faces = np.random.randint(0, N_vert, size=(N_face,3))
ps_mesh = ps.register_surface_mesh("my mesh", vertices, faces)

# add a parameterization (aka UV map)
param_vals = np.random.rand(ps_mesh.n_vertices(), 2)
ps_mesh.add_parameterization_quantity("test_param", param_vals, 
                                      defined_on='vertices', enabled=True)

# add the texture quantity
dims = (200,300,3)
color_vals = np.random.rand(*dims) # dummy placeholder image data
ps_mesh.add_color_quantity("test_vals", color_vals, 
                           defined_on='texture', param_name="test_param", 
                           enabled=True)

ps.show()

Texture image data is added via add_color_quantity(), with defined_on='texture' and param_name=... specifying the name of the parameterization UV map with coordinates on [0,1] which will be used to sample from the image.

The texture image data, dimension, and origin conventions are the same as those used to define images. See there for details.

Color Quantity Options

When adding a color quantity, the following keyword options can be set. These are available for all kinds of color quantities on all structures.

Keyword arguments:

  • enabled boolean, whether the quantity is initially enabled (note that generally only one quantitiy can be shown at a time; the most recent will be used)

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