Hi Christian, adding 'axis equal' helps somewhat but the image remains an ellipsoid.
An orthogonal projection of a sphere in any direction should
look like a circle, shouldn't it? What I am getting in pgfplots
is not a circle. I have attached a sample image produced by
the following code:
\documentclass{article}
\usepackage{pgfplots}
%\usepgfplotslibrary{external}
%\tikzexternalize
\begin{document}
\begin{tikzpicture}
\begin{axis}[view={60}{30}, axis equal=true]
\addplot3[surf, z buffer=sort, domain=0:180, y domain=0:360]
({sin(x)*cos(y)},
{sin(x)*sin(y)},
{cos(x)}
);
\end{axis}
\draw (3.45,2.85) circle(1.8); % for comparison
\end{tikzpicture}
\end{document}
Rouben
PS: Changing the view option to `view={45}{0}' produces even
a more drastic illustration of the flattening of the sphere.
---- original message -------------------------------------------
From: Christian Feuersaenger <cfeuersaen...@googlemail.com>
Date: Wed, 25 Apr 2012 20:37:41 +0200
To: Rouben Rostamian <rostam...@umbc.edu>, 'PGFplots mailing list'
<pgfplots-features@lists.sourceforge.net>
Subject: Re: Plotting a sphere in pgfplots
Hi Rouben,
the result actually *is* a sphere - but the coordinate system is
skewed because the axes do not have the same units.
The option 'axis equal' for \begin{axis} will fix it.
Best regards
Christian
Am 24.04.2012 03:58, schrieb Rouben Rostamian:
>Hello Christian,
>
>I have a rather basic question about pgfplots.
>I am trying to plot a sphere, like this:
>
>\documentclass{article}
>\usepackage{pgfplots}
>\begin{document}
>\begin{tikzpicture}
> \begin{axis}[view={60}{30}]
> \addplot3[surf, z buffer=sort, domain=0:180, y domain=0:360]
> ({sin(x)*cos(y)},
> {sin(x)*sin(y)},
> {cos(x)}
> );
> \end{axis}
>\end{tikzpicture}
>\end{document}
>
>The result appears to be an ellipsoid rather than a sphere.
>(I am using pgfplots 1.4.1.) I suspect that I have failed
>to specify an essential parameter. I searched the manual
>but didn't find the necessary information. Would you please
>tell me how to make a sphere that looks like a sphere?
>
>Rouben
>
>
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