[Pmb (OP)]

I'm looking for freeware software that will generate images of simple geometric 3d objects such as a sphere with specific latitude and longitide lines drawn on them. Can someone recommend some software that will do this which is free and can be downloaded online? I'm searching through download.com at the moment.

[Pmb (OP)]

Nobody here with this kind of knowledge, huh?

[RD]

https://en.wikipedia.org/wiki/List_of_computer-aided_design_editors [only a few on that list are free]

I didn't see blender on that list, (which is free).
 
[also see Mandelbulb for freaky 3D fractal shapes ]

Update: "Blender" is on this list ... https://en.wikipedia.org/wiki/Comparison_of_3D_computer_graphics_software

[The videos of Sculptris on YouTube look amazing ...

]

[RD]

Free Image manipulation software called GIMP can map an image onto a sphere ...   

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If the image included a grid, mapping it onto a sphere would produce latitude and longitude lines.
[ GIMP is primarily a photoshop-type program, flat-2D stuff, not 3D modelling ]

[CliffordK]

I always seem to have issues with some of the free graphics programs.  I'll have to look at the 3D mapping with GIMP.

It looks like Autodesk now is giving away free student editions of all of their software.
http://students.autodesk.com/
Fully functional, but with a watermark (and licensing restrictions).

You search Google for free CAD programs.
Here are some suggestions from About.com

[RD]

I always seem to have issues with some of the free graphics programs.  I'll have to look at the 3D mapping with GIMP.

The 3D mapping options on GIMP are very limited ...

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[Pmb (OP)]

Thanks for the recomendations.

What I'm looking for is software to help me create figures for mathematics to help the reader understand what's going on. For example: suppose I wanted to draw a sphere and then draw coordinates on the sphere. First thing to know is that the sphere has to have shading on it. How do we do that? I.e. what software w

[RD]

... For example: suppose I wanted to draw a sphere and then draw coordinates on the sphere. First thing to know is that the sphere has to have shading on it. How do we do that? I.e. what software w

GIMP will map an image onto a sphere and add shading ...

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[ I added a grid to the image before it was mapped to sphere, which produces lines of longitude and latitude ] 

[RD]

Ooh just noticed GIMP does a spinning globe effect too ...

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But like I said previously GIMP is primarily 2-D image manipulation, rather than 3-D modelling program.

[Pmb (OP)]

GIMP will map an image onto a sphere and add shading ...

 [ You are not allowed to view attachments ]    [ You are not allowed to view attachments ]

[ I added a grid to the image before it was mapped to sphere, which produces lines of longitude and latitude ] 

Very cool. Thanks whole bunch!

However that won’t work in general. In more complicated situations. For example: use the software to draw 3 arbitrary great circles on a sphere.

In case you don’t know what a great circle is please see
http://mathworld.wolfram.com/GreatCircle.html

[RD]

... For example: use the software to draw 3 arbitrary great circles on a sphere.

No that would be beyond the scope of GIMP.

Wings3D [free, open-source] looks like a 3D equivalent of GIMP ... http://en.wikipedia.org/wiki/Wings3d

There are on-line 3D modelling websites, but I've not used them,
 ( I tried a couple, no joy as apparently my computer lacks a compatible graphics-card ).

[RD]

http://www.hongkiat.com/blog/25-free-3d-modelling-applications-you-should-not-miss/