sphereModel

Object for storing a parametric sphere model

Description

The sphereModel object stores a parametric sphere model.

Creation

Syntax

model = sphereModel(parameters)

Description

model = sphereModel(parameters) constructs a parametric sphere model from the specified parameters. The parameters argument is a 1-by-4 numeric vector that determines the value of the Parameters property.

Input Arguments

parameters — Sphere parameters

1-by-4 scalar vector

Sphere parameters, specified as a 1-by-4 vector. This input specifies the Parameters property. The four parameters [a b c d] satisfy this equation for a sphere:

$${(x-a)}^2+{(y-b)}^2+{(z-c)}^2=d^2$$

Properties

Parameters — Sphere model parameters

1-by-4 numeric vector

This property is read-only.

Sphere model parameters, stored as a 1-by-4 numeric vector. This property is set by the parameters input. The four parameters [a b c d] satisfy this equation for a sphere:

$${(x-a)}^2+{(y-b)}^2+{(z-c)}^2=d^2$$

Center — Center of sphere

1-by-3 vector

This property is read-only.

Center of the sphere, stored as a 1-by-3 vector of form [xc yc zc]. The elements xc,yc,zc specify the x-, y-, and z-coordinates of the center coordinates of the sphere, respectively.

Radius — Radius of sphere

scalar

This property is read-only.

Radius of the sphere, stored as a scalar value.

Object Functions

plot	Plot parametric model
findPointsInModel	Find points in or on surface of geometric model

Examples

Detect Sphere in Point Cloud

Load a point cloud into the workspace.

load("object3d.mat");

Display the point cloud and label the figure.

figure
pcshow(ptCloud)
title("Detect a sphere in a point cloud")

Set the maximum point-to-sphere distance for sphere fitting to 1cm.

maxDistance = 0.01;

Set the region of interest to constrain the search.

roi = [-inf,0.5;0.2,0.4;0.1,inf];
sampleIndices = findPointsInROI(ptCloud,roi);

Detect the globe in the point cloud and extract it.

[model,inlierIndices] = pcfitsphere(ptCloud,maxDistance,SampleIndices=sampleIndices);
globe = select(ptCloud,inlierIndices);

Plot the extracted globe.

figure
pcshow(globe)
title("Globe Point Cloud")

Version History

Introduced in R2015b