How get a giga pixel image out of a normal photo clicked with a nikon d3100 18-55mm lens?

How get a giga pixel image out of a normal photo clicked with a nikon d3100 18-55mm lens?

Out of a single one? No way. The information is not there.

You'd have to put it on a tripod, take about a hundred slightly overlapping photos, and have them stitched together with special software to form a single gigapixel image.

That's not something the average amateur usually does. Stitching up a panorama is one thing, a gigapixel image quite another.

I agree with the Jens. You could 'up-sample' with photoshop, increasing by 10% at a time (increasing in small increments is more accurate). But, it just won't be the same. Taking lots lots lots of pictures and stitching them together using autodesk stitcher or photoshop (select your photos in bridge, and automate the process) would get you close, but not quite…

Here is how I did that.

I shot and saved the image as a RAW file.

When I processed the RAW file, I saved it as a 16-bit TIFF file (no compression)

I cropped that file to a 4x6 foot image @ 300 DPI and saved that image to another 16-bit TIFF. The resulting file was a 1.7 GB file. Adobe up-sampled the final file but it took nearly half an hour for the new file to compile.

When you are shooting for such large prints, be sure that you have the image perfectly exposed, in absolute focus and that there's NO camera or subject movement

Note: Forget the term 'clicking'. That is something my mom did with her point and shoot camera. Photographers expose their images using the shutter release after carefully composing their shot. This takes discipline. Clicking requires very little thought and is sometimes called a "snap-shot"

Not possible. By definition, gigapixel images are made up of multiple images. If you have a 10 megapixel camera, it would take at least 100 images stitched together to make a gigapixel image. (Technically more, since there would be overlap.)