remapping sphere (from outside) to a flat projection

[lloyd.h...@gmail.com]

Hello - could anyone think of a way to accomplish this using hugin or any other software? I want to take a map that has been drawn on the surface of a painted-over globe, and create a flat image file that I could then reproject using other software (e.g. NASA G.Projector). My idea is that it should be possible to photograph the globe from several overlapping angles (from as far away as possible to minimise distortion) then have software stitch the images together, generating an equi-rectangular representation (or some other flat representation - I don't mind, as I can use other software to translate). It's just that initial step of getting the images stitched together in the first place that I can't plan right now.

I figure since hugin and other software can generate a spherical panorama viewed from the inside, it shouldn't be beyond the realm of possibility to generate a spherical surface from pictures taken from the outside.

Thanks in advance for any ideas.

Lloyd

[Jim Watters]

If you place the a large heavy glass or something similar on the floor and place
the globe in and the camera on a tripod from above. Shoot with a normal lens.
You should be able to rotate the globe without moving the tripod or glass and be
able to capture the whole surface. You will want to capture at least 6 shots
around plus the two poles. If you want higher resolution you can use a longer
lens and take more pictures.

I believe if you set the lens type as fullframe fisheye and allow for heavy abc
distortion it should stitch.
You will get an equirectangular image.

--
Jim Watters
http://photocreations.ca

[lloyd.h...@gmail.com]

Hi Jim and thanks for your reply. I apologise but I don't understand the point of the "large heavy glass". Why couldn't I just set the camera up on a tripod, aim it at the globe across the room, and take several pictures while I rotate the globe, without otherwise moving it, by 60 degrees or so each time, with no glass involved anywhere?

And sorry to be "that guy" but could you explain in a little more detail the following:

I believe if you set the lens type as fullframe fisheye and allow for heavy abc
distortion it should stitch.
You will get an equirectangular image.

I've never used hugin before so if you could just elaborate a little on the steps that will be involved once I have my 8 or so photos (cropped, I assume, to a circular shape) - do I have to specify which photos are of the poles or will it figure it out automatically?

I appreciate it. Lloyd.

[Jan Martin]

Hi Loyd,

I think Jim assumed you have a globe without stand.

Just do as you thought. Images will be fine.

Your project sounds interesting.
Please upload the images to make them available.
We will have a look and then provide you with the hugin configuration file, so you can see how it is done.

It is hard to describe the complete process with all if-then-else cases key-by key to a rookie.

Jan

--
A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ
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[lloyd.h...@gmail.com]

Thanks for the offer Jan. I will have to finish sketching on the globe, then I'll take the pictures and post them. (I'll post a very rough version, to get a feel for the technique, then I can redo the globe more nicely and tweak the importing/reprojecting part of the task at my leisure.)  --Lloyd

[Erik Krause]

Am 17.08.2013 19:59, schrieb lloyd.h...@gmail.com:

> I figure since hugin and other software can generate a spherical panorama
> viewed from the inside, it shouldn't be beyond the realm of possibility to
> generate a spherical surface from pictures taken from the outside.

Michel Thoby has done this some time ago:
http://tinyurl.com/cdnzd2
He used PTGui. But it should be possible with hugin likewise.

--
Erik Krause
http://www.erik-krause.de

[Carlos Eduardo G. Carvalho (Cartola)]

Cool!

Carlos E G Carvalho (Cartola)
http://cartola.org/360
http://www.panoforum.com.br/

2013/9/1 Erik Krause <erik....@gmx.de>

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