I was doing some research on making 3d models out of many many pictures and i came across a good many software and 2 of my favorite are
- 123d catch by autodesk ( http://www.123dapp.com/catch )
- 3dsom ( http://www.3dsom.com )

123d catch is more powerful and user friendly in my opinion, you just snap a ton of pictures, upload and wait, then TADA its done. they have somehow managed to determine the location of your camera relative to the object from all that pictures you take and through some modern magic build a 3d model and send it back to you.

But I my case, i preferred 3dsom as all the computing is done locally on my laptop which is better for me as my isp decided i dont need any upload speed. As you can guess, uploading some 50-100 high quality photos at 0.1Mbps is not too productive.
Anyway, 3dsom has its limitations too, one of which is that it produces models that are very distorted when not done meticulously.

My solution is to use my NXT set to spin my model on the turntable and snap the pictures for me, that way the pictures are very consistent and i just need a few minutes to set it up and let it do its thing.

If anything is not clearly written, refer to the pictures, if you are still not sure you can post a comment or send me a message

Step 1: The Turntable

First obtain a legal copy of the 3dsom software from their website. (link in intro page) then print out the mat.
you would want to cut the mat into a circle and cut a matching size cardboard to paste it onto as you want it to be stiff and rigid so you can put your models on it. any stiff and light material would do maybe straw-board, wood, plastic but i used cardboard.

Now to secure the platform/mat to an axle. To do this, mark the center of the platform and since i am using Lego, I securely taped a wheel hub to the underside making sure the axle is dead center. If tape is not working, use more tape =p

I am just providing the basic idea behind this so i wont go into detail of the construction of the lego parts used.
anyway, i power the turntable with 2 NXT motors and geared it down a little for that added precision and to slow it down a bit and to make sure i am not lacking power to turn any heavy models.

Next I set the motors and platform on a stable base which also holds a mounting board to be used as background.
Just flip the mounting board over to switch between black and white backgrounds, try and use a background that gives the most contrast to the model.

Step 2: The Auto-shutter-clicker + Tripod

You can skip this step if you have other methods to have the robot press the shutter release for you, maybe you have a remote for the camera or so other means to do this. But the idea is to have a picture taken every few degrees the table turns.

My solution is to built a cage to secure my camera in and have the NXT motor press the shutter release
as the design of each camera will be different you might want to make one that fits your own camera. But there are a few tricks here which might help, please take a look at the pictures.

i used a normal commercial tripod you can get from any photography shop and found a Lego part which attaches nicely to the tripod
The cage/mount is constructed entirely out of Lego and i used many rubber parts to ensure i don't damage my camera and it is held securely .
you can have a look at this Lego part in the picture I made the cage such that it can be fixed to the tripod in landscape or portrait orientation.

To press the shuttle release button, the motor drives a pin which acts as a cam the pushes an L shaped part which is pivoted at one end and the other end is on top of the button. The pin pushes on the corner allowing the L part to press the button gently.

Step 3: Setting Up

The setup is pretty straightforward just place the tripod and auto-shutter-clicker as show below.
adjust the camera angle to your own discretion. Try and get a good view of the mat so the software can do its thing.

you would also want a contrasting background as it helps when you clean up the photos

Step 4: Working With the Software

First a few pictures on roughly how the pictures taken should look like, i took about 100 photos for this model, 50 from 1 elevation and another 50 from a higher angle for this project, i used a pedestal to help get better shots, its optional though

You would want to using a contrasting background as mentioned before to help you isolate the model from the background.
Just keep doing this for all your pictures, the better you do the better the results
you can use the automask feature to help mask it before touching it up manually, that saves you a lot of time

So as you can see, you can get a reasonable quality model with this setup. This is not the best i have done, and i am sure others have done much better. So i hope this helps and may you make a better one and post it up here on instructables

Step 5: Video Time!

Here are 2 videos of it in operation

The second video

Notice i did not need the pedestal for this round of photoshot

Step 6: Final Word

Thanks for taking a look at my instructable, I hope you learned something useful.
If any part of the instructable is not clear or you disagree with any part of it, please drop me a comment or send me a message