Generating STL (3D) file from raster ASTER GDEM data?

I know QGIS has a plugin that export DEM to STL using DEMto3D, and I tested on a DEM and it worked. The description of the plugin mentioned that clearly:

DEMto3D is the first tool that links GIS (Geographic Information System) and 3D printing. DEMto3D allows export DEM to STL format ready to 3D printing.

Here is the homepage of the demto3d, and there is video demonstrating the plugin, but it is not in English. However, you can still use the plugin to export the DEM to STL.

To demonstrate how DEMto3D plugin works, I used a sample of ASTER GDEM, as you can see below:

You can set the extent of the STL model to be exactly same as the extent of the DEM automatically, or you can choose a subset of the DEM, so I will leave this to you.

The most important part is the model size, you need to be careful about that to make a balance between the computer efficiency and the details of the model, so you need to do the necessary calculations in the model resolution (spacing in mm), the model area (width and length) in the setup, and the scale. However, it is not difficult because when you change the scale, for example, the Model area will be updated.

I used an exaggeration factor of 5, but you can choose whatever you like. Then you need to set the base height of the model, I consider it 0.

Here is the output STL file loaded using MashLab software:

(1) Top View:

(2) Oblique 3D View:

Changing projection from geographic to UTM, for example, didn't give different result. Here is the settings and result of the same DEM in UTM projection:

Using QGIS, you can install the DEMto3D-plugin, as ahmadhanb mentioned. As ASTER dem's come with a geographic coordinate system, i would suggest to project the data to a cartesian coordinate system. The plugin will then convert the coodinates into a 3D-Space that has its origin, size and hights "printer ready". In a Dialog you can specify the parameters for the output size. Output files will be in the stl ascii format. I imported the output file in blender, which works like a charm und looked good.

The tutorial below gives detailed instructions to convert a DEM raster into an stl for 3D printing. It uses QGIS to process the DEM to a tiff. It then uses 3DEM (free) to convert the tiff to .dem format. It then uses AccuTrans3D (free as trial) to convert the .dem to .stl. You can then edit the stl in blender or a similar program.

Here's the tutorial: http://www.the3dprintedfuture.com/shapespeare/?p=1

EDIT: Now that I know about the DEMto3D plugin in QGIS, I think that is the best option to convert a raster to stl - thank you to ahmadhanb and Andreas for bringing this plugin to light.