3D models for robot using SketchUp and exporting them to Alice

1/22/2012

I was looking for an alternative to a CAD (computer aided design) program so that I could do some simple work with 3D models of the robot. I have used Google SketchUp before and I was very satisfied with how it works but it wasn't until recently that I thought to use it for modeling projects. Google SketchUp is simple and easy to use compared to many other free 3D graphics programs that are available. Although SketchUp lacks the advanced features of programs like AutoCAD which can actually be used to make the objects that you draw by feeding the file into a CNC milling machine it is still very useful for creating conceptual images and animations.

Exporting 2D images from SketchUp:

By choosing SketchUp I was sure that I would not using these models to create parts but to simply to model form and function of the robot so that I could generate images like the ones bellow or potentially to create animations. The 3D image part is easy as SketchUp has a built-in image exporter: (File --> Export --> 2D Graphic...). Alternatively, if for some reason you are unable to use the built-in exporter you can always just take a screen capture by pressing the 'PrintScr' key on the keyboard and then right clicking and selecting paste in a blank word or image file.

Exporting 3D images from SketchUp to Alice:

Robot model loaded into 3D world

As for my intention to create 3D animations of the robot, that would be a bit more difficult. I learned programming using a language called Alice. Alice is a beginner programming language that uses its code to control 3D objects in a simulated world. SketchUp saves by default in a .skp format that as far as I know only SketchUp can read, but it can export files as a .dae format which can be read by some other 3D object programs. In order to load 3D objects made in SketchUp into Alice they first need to be converted to a .ase format. The process of doing this is a bit complicated but here it goes:

You will need to download and install/extract the following programs (all are free to use).

GoogleSketchup: http://sketchup.google.com/
Blender: http://www.blender.org/download/get-blender/
Biturn: http://mirex.mypage.sk/
Alice: http://www.alice.org/

Export your object made in SketchUp as a .dae file by going to File --> Export --> 3D Graphic... and then save it with a .dae after the name.
Open Blender and import the .dae file using File --> Import... and then choose your .dae file. If your object looks broken or distorted in blender you may have to go back to SketchUp and open your original .skp file. Press 'Ctrl+a' on the key board to select all parts of the object then right click on it and choose 'Explode'. You must then re-export it as done in step 2.
In Blender go to File --> Export... and choose the .obj format. Export the .obj file.
Open Biturn and open your .obj file. Then export it as a .ase file.
Run Alice and open a blank world. Go to File --> Import... and choose your .ase file. It should load and you may have to re-size it as it may be out of proportion with the rest of the world.

You can now experiment by writing your own code to move the object. You can also add other pre-made objects to the world to make it more interesting. Alice has a built in video exporter so that you can export your videos directly as movies.

My completed 3D animation using my custom model: